Starches for Food Application 9780128094402, 0128094400

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STARCHES FOR FOOD APPLICATION

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STARCHES FOR FOOD APPLICATION Chemical, Technological and Health Properties

Edited by

MARIA TERESA PEDROSA SILVA CLERICI University of Campinas, School of Food Engineering, Campinas, SP, Brazil

MARCIO SCHMIELE Federal University of Jequitinhonha and Mucuri Valleys, Institute of Science and Technology, Diamantina - MG, Brazil

Academic Press is an imprint of Elsevier 125 London Wall, London EC2Y 5AS, United Kingdom 525 B Street, Suite 1650, San Diego, CA 92101, United States 50 Hampshire Street, 5th Floor, Cambridge, MA 02139, United States The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, United Kingdom Copyright © 2019 Elsevier Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library ISBN: 978-0-12-809440-2 For information on all Academic Press publications visit our website at https://www.elsevier.com/books-and-journals

Publisher: Andre Gerhard Wolff Acquisition Editor: Nina Rosa de Araujo Bandeira Editorial Project Manager: Billie Jean Fernandez Production Project Manager: Nilesh Kumar Shah Cover Designer: Matthew Limbert Typeset by TNQ Technologies

From Maria Teresa P.S. Clerici: I dedicate this book to my son, Rafael P.S. Clerici, and my students, because they motivate me to always move on. From Marcio Schmiele: I dedicate this book to the food science, chemistry, and technology professionals. From Teresa and Marcio: We dedicate this book to all the authors quoted within it, both those who contributed directly to the writing of their chapter and those who contributed indirectly, through the literature cited.

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CONTENTS Contributors Preface

1. Basic Principles: Composition and Properties of Starch

xi xiii

1

Marcio Schmiele, Ulliana Marques Sampaio and Maria Teresa Pedrosa Silva Clerici 1.1 Introduction 1.2 Obtaining Starch 1.3 Chemical Composition of Starch 1.4 Properties 1.5 Conclusion References Further Reading

2. Identification and Analysis of Starch

1 3 8 12 18 19 22

23

Maria Teresa Pedrosa Silva Clerici, Ulliana Marques Sampaio and Marcio Schmiele 2.1 Introduction 2.2 Identification of the Starch Grain 2.3 Physicochemical Characterization 2.4 Morphological and Structural Characterization 2.5 Rheological Characterization 2.6 Technological Characterization 2.7 Nutritional Characterization 2.8 Biodegradation of Starch-Based Packages 2.9 Future Trends 2.10 Conclusion References Further Reading

3. Cereal Starch Production for Food Applications

24 25 29 36 44 52 56 57 57 58 58 69

71

Edith Agama-Acevedo, Pamela Celeste Flores-Silva and Luis Arturo Bello-Perez 3.1 Starch Overview 3.2 Starch Production and Modification 3.3 Physicochemical and Functional Properties

71 76 83

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Contents

3.4 Starch Digestibility 3.5 Food Applications 3.6 Final Remarks References Further Reading

4. Starch Extracted From Corms, Roots, Rhizomes, and Tubers for Food Application

87 92 95 96 102

103

Olivier François Vilpoux, Vitor Hugo Brito and Marney Pascoli Cereda 4.1 4.2 4.3 4.4 4.5

Introduction Commercial Starch Worldwide Crops that Store Starch in Underground Organs How to Find Interesting Starches With Potential Uses The Starches With the Most Potential: Their Advantages and Disadvantages 4.6 Final Considerations References

5. Starch Valorization From Corm, Tuber, Rhizome, and Root Crops: The Arrowroot (Maranta arundinacea L.) Case

104 106 114 134 143 154 156

167

Denilson de Oliveira Guilherme, Fabiano Pagliosa Branco, Nuno Rodrigo Madeira, Vitor Hugo Brito, Carina Elisei de Oliveira, Cleber Junior Jadoski and Marney Pascoli Cereda 5.1 Introduction. Why Arrowroot Starch? 5.2 The Genetic Variation of the Brazilian Arrowroot 5.3 Botanical Aspects and Rhizome Characterization of Maranta arundinacea Variety Comum 5.4 The Arrowroot Starch 5.5 Commercial Cultivation of Arrowroot: What We Have and What We Need 5.6 Arrowroot Extraction Using Small-Scale Equipment 5.7 The Future: Final Considerations Acknowledgments References Further Reading

6. Physical Modifications of Starch

168 171 176 182 192 209 211 213 214 222

223

Marcio Schmiele, Ulliana Marques Sampaio, Paula Thamara Goecking Gomes and Maria Teresa Pedrosa Silva Clerici 6.1 Introduction 6.2 Conventional Gelatinization Processes

224 225

Contents

6.3 Microwave Cooking 6.4 HeateMoisture Treatment 6.5 Cold-Water Swelling 6.6 Annealing 6.7 High Hydrostatic Pressure 6.8 Milling 6.9 High-Speed Shear 6.10 Ultrasonic Modification 6.11 Cold Plasma 6.12 Other Physical Modification Methods 6.13 Future Perspectives References

7. Starches Modified by Nonconventional Techniques and Food Applications

ix 231 234 235 237 238 242 247 247 252 255 259 259

271

Xiangli Kong 7.1 Introduction 7.2 g-Irradiation 7.3 Electron Beam 7.4 Plasma 7.5 Ultrasonic Treatment 7.6 Microwave 7.7 Conclusions References

8. Physicochemical Properties, Modifications, and Applications of Resistant Starches

271 272 276 277 278 283 286 287

297

Serpil Öztürk and Selime Mutlu 8.1 Introduction 8.2 Definitions and Types of Resistant Starch 8.3 Production and Modification of Resistant Starch 8.4 Physiological Effects of Resistant Starch 8.5 Physicochemical Properties of Resistant Starch 8.6 Food Applications of Resistant Starch 8.7 Conclusion References

297 299 303 307 310 314 324 325

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Contents

9. Technological and Nutritional Applications of Starches in Gluten-Free Products

333

Yaiza Benavent-Gil and Cristina M. Rosell 9.1 9.2 9.3 9.4

Introduction Gluten-Free Breads Understanding the Role of Starch in Gluten-Free Products Relationship Between Starch Properties and Gluten-Free Product Performance Acknowledgments References

10. Starch-Based Edible Films and Coatings: An Eco-friendly Alternative for Food Packaging

333 335 339 351 352 352

359

Franciele Maria Pelissari, Danielle Cristine Ferreira, Ludmilla Batista Louzada, Fabiana dos Santos, Ana Carolina Corrêa, Francys Kley Vieira Moreira and Luiz Henrique Mattoso 10.1 General Overview 10.2 Starch as a Sustainable Polymer 10.3 Film-Forming Methods 10.4 Properties of Starch-Based Films 10.5 Starch-Based Composites and Nanocomposites 10.6 Increasing the Shelf Life of Foods 10.7 Conclusions and Future Perspectives Acknowledgments References Index

360 361 365 374 388 396 405 406 406 421

CONTRIBUTORS Edith Agama-Acevedo Centro de Desarrollo de Productos Bióticos del Instituto Politécnico Nacional, Yautepec, Mexico Luis Arturo Bello-Perez Centro de Desarrollo de Productos Bióticos del Instituto Politécnico Nacional, Yautepec, Mexico Yaiza Benavent-Gil Institute of Agrochemistry and Food Technology (IATA-CSIC), Valencia, Spain Fabiano Pagliosa Branco Catholic University (UCDB), Tamandaré, # 6000, Campo Grande, MS. 79117-900 Vitor Hugo Brito Center of Technology and Agribusiness Analysis - Catholic University (CeTeAgro/ UCDB), Campo Grande, Brazil; EMBRAPA/Vegetables, Brasília, Brazil Marney Pascoli Cereda Center of Technology and Agribusiness Analysis - Catholic University (CeTeAgro/ UCDB), Campo Grande, Brazil Maria Teresa Pedrosa Silva Clerici University of Campinas, School of Food Engineering, São Paulo, Brazil Ana Carolina Corrêa National Nanotechnology Laboratory for Agribusiness, Embrapa Instrumentation, São Carlos, Brazil Denilson de Oliveira Guilherme Center of Technology and Agribusiness Analysis - Catholic University (CeTeAgro/ UCDB), Campo Grande, Brazil Fabiana dos Santos Laboratory of Green Materials, Food Engineering, Institute of Science and Technology, University of Jequitinhonha and Mucuri, Diamantina, Brazil Danielle Cristine Ferreira Laboratory of Green Materials, Food Engineering, Institute of Science and Technology, University of Jequitinhonha and Mucuri, Diamantina, Brazil Pamela Celeste Flores-Silva Centro de Desarrollo de Productos Bióticos del Instituto Politécnico Nacional, Yautepec, Mexico Paula Thamara Goecking Gomes Federal University of Jequitinhonha and Mucuri Valleys, Institute of Science and Technology, Diamantina, Minas Gerais, Brazil

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Contributors

Cleber Junior Jadoski Catholic University (UCDB), Tamandaré, # 6000, Campo Grande, MS. 79117-900 Xiangli Kong College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China Ludmilla Batista Louzada Laboratory of Green Materials, Food Engineering, Institute of Science and Technology, University of Jequitinhonha and Mucuri, Diamantina, Brazil Nuno Rodrigo Madeira EMBRAPA/Vegetables, Brasília, Brazil Luiz Henrique Mattoso National Nanotechnology Laboratory for Agribusiness, Embrapa Instrumentation, São Carlos, Brazil Francys Kley Vieira Moreira Department of Materials Engineering, Federal University of São Carlos, São Carlos, Brazil Selime Mutlu Department of Food Engineering, Faculty of Engineering, Sakarya University, Esentepe, Sakarya, Turkey Carina Elisei de Oliveira Catholic University (UCDB), Tamandaré, # 6000, Campo Grande, MS. 79117-900 Serpil Öztürk Department of Food Engineering, Faculty of Engineering, Sakarya University, Esentepe, Sakarya, Turkey Maria Teresa Pedrosa Silva Clerici University of Campinas, School of Food Engineering, Campinas, São Paulo, Brazil Franciele Maria Pelissari Laboratory of Green Materials, Food Engineering, Institute of Science and Technology, University of Jequitinhonha and Mucuri, Diamantina, Brazil Cristina M. Rosell Institute of Agrochemistry and Food Technology (IATA-CSIC), Valencia, Spain Ulliana Marques Sampaio University of Campinas, School of Food Engineering, Campinas, São Paulo, Brazil Marcio Schmiele Federal University of Jequitinhonha and Mucuri Valleys, Institute of Science and Technology, Diamantina, Minas Gerais, Brazil Olivier François Vilpoux Center of Technology and Agribusiness Analysis - Catholic University (CeTeAgro/ UCDB), Campo Grande, Brazil

PREFACE As the editors of this book, we would like to thank all the authors who collaborated with us and their respective institutions, as this contribution allowed us to prepare a book of high quality, easy to understand and read. This book may be useful to students and practitioners in the field of food science, chemistry, and technology, beginners or not, as we approach the study in a growing form of knowledge from the introductory part (Chapters 1 and 2) with key concepts and methods of starch analyses. As a distinction, in our presentation of cereal (Chapter 3) and tuber (Chapter 4) starches, a chapter on a case study (Chapter 5) is included, in which the respective authors present the efforts for the industrialization of arrowroot, which is a starch source little exploited. It is worth checking out how the project was developed and the new equipment that was proposed for the farmer, who still works on a semi-industrial scale. Chapter 6 deals with the physical methods of extracting starch, demonstrating the great advances in this area and the increasing importance of new physical methods, since in addition to the health appeals for GRAS starch consumption, the desire for environmental sustainability has focused on preventing or decreasing the generation of effluents, resulting in naturefriendly processes. In all chapters, whenever possible, we address the importance of methods of obtaining and analyzing slowly digestible and/or resistant starches, with chapters devoted entirely to these subjects (Chapters 7 and 8). It is worth emphasizing that although starch is a great power supply with fundamental importance for humans, it can lead to the development of diseases such as obesity, diabetes, and other disorders when consumed in high concentrations, so the demand for slowly digestible starches and resistant starches has been intense, since they may be used in food products, leading to health benefits. In the last two chapters, we present some applications of starches, for gluten-free products (Chapter 9) or the formation of films and edible coverings (Chapter 10). These two different applications have advanced a lot in the past decades and the products are within the quality standards considered suitable for commercialization, which has already happened in the area of bakery items and packaging.

xiii

xiv

Preface

Throughout the book, the reader can note the great change in starch concepts that began at the end of the past century; once starch was considered only as an energetic source of rapid glucose release, but it is now recognized that when boiled, three major nutritional forms are developed, including rapidly digestible starch, slowly digestible starch, and starch resistant to digestion by the human digestive system. Possibly, new methods of genetic, enzymatic, and/or physical modification will be capable of developing starch with a controlled release of glucose, providing the beneficial effects such as the arrival of glucose to the brain, retina, and labyrinth, without causing the malignant effects of increased blood glucose and consequently insulin, allowing a better quality of life among the population. Finally, we thank Billie and Nina for their understanding throughout the preparatory process of this book.

CHAPTER 1

Basic Principles: Composition and Properties of Starch Marcio Schmiele1, Ulliana Marques Sampaio2, Maria Teresa Pedrosa Silva Clerici2 1

Federal University of Jequitinhonha and Mucuri Valleys, Institute of Science and Technology, Diamantina, Minas Gerais, Brazil; 2University of Campinas, School of Food Engineering, Campinas, São Paulo, Brazil

Contents 1.1 1.2 1.3 1.4

Introduction Obtaining Starch Chemical Composition of Starch Properties 1.4.1 Gelatinization and Retrogradation 1.4.2 Ability to Undergo Changes 1.5 Conclusion References Further Reading

1 3 8 12 14 17 18 19 22

1.1 INTRODUCTION Until recently, starch was considered the main energy source for human food; however, its nutritional role has expanded, because it also represents a source of dietary fiber. The evolution of the genetic, chemical, and technological fields has led to the production of starches with changes in digestibility and resistance to the enzymes of the digestive system (Fuentes-Zaragoza et al., 2010; Jane, 2004; Goni et al., 1997; Eerlingen and Delcour, 1995). Today, there is an increasing demand for healthier products, without changing the sensory properties of the processed Starches for Food Application ISBN 978-0-12-809440-2 https://doi.org/10.1016/B978-0-12-809440-2.00001-0

© 2019 Elsevier Inc. All rights reserved.

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Starches for Food Application

products, and a variety of modified starches are available to meet these criteria. Starch can be produced by conventional or family farming and is a source of subsistence for many farmers. The major starch sources are cereals, such as corn, and tubers and roots, such as potatoes and cassava. Starches are used for different purposes in food, including the production of glucose and/or fructose syrups, or as thickening agents and fat substitutes, among others (Fig. 1.1). In other areas, starch has been increasingly used in several industries, such as paper, textiles, pharmaceuticals, cosmetics, packaging, and steel, among others, as stated by Whistler and Paschall (1965), Wurzburg (1989), Eliasson (2004), BeMiller and Whistler (2009), and Bertolin (2010). This great improvement may completely change the concept that starchy products are among the main causes of obesity, type 2 diabetes, and other chronic noncommunicable diseases (Escott-Stump et al., 2013). In the future, starch may be consumed as a source of slow release of glucose, which is essential for the brain, retina, labyrinth, and nervous system. With optimized starch use, there will be no excess glucose in the blood vessels, thus reducing fatty acid conversion, which, when in abundance, is harmful to the human body. With the great variety of modified starches and new modification techniques, in the future, engineering aimed solely at obtaining a specific starch for each human need may be a reality. Today, modification processes have been developed according to purpose, for example, the type IV resistant starches, which are modified chemically to resist the enzymes of the digestive system and innumerable processing conditions, including high temperatures, high pressure, and acidic pH, among other aggressive conditions, especially for those foods subjected to sterilization. This chapter will address the basic principles to familiarize the reader and facilitate the understanding of the following chapters.

Basic Principles: Composition and Properties of Starch

3

Figure 1.1 Production of starch and its various applications.

1.2 OBTAINING STARCH Starch and similar molecules can be found in plants, bacteria, and algae. In animals, glycogen, formed by glucose molecules, is present in muscle and liver in small amounts for maintaining

4

Starches for Food Application

essential activities in the body. In bacteria and algae, studies have found new sources of carbohydrates for human consumption (Eliasson, 2004; BeMiller and Whistler, 2009). Economically, the starch of plant origin is the one with major importance for the food industry. In plants, starch is stored inside plant cells in the form of energy, found in both chloroplasts (chlorophyll-containing plastids) as a transitory starch, being synthesized during photosynthesis and consumed at night by the plant, and amyloplasts, in which the synthesis and degradation occur at separate times, with accumulation of starch at high concentrations in the reproductive structures (grains), vegetative structures (tubers, stems), fruits (banana, wolf fruit, and others), and roots (cassava, taro), to be used in other phases (germination, budding, fruit ripening, and others) (Eliasson, 2004; BeMiller and Whistler, 2009). For extraction and industrial processes, the starch stored in the amyloplasts has the greatest economic viability. Starch extraction methods are well established for commercial cereals and roots, but should be adapted to the new sources of starch, such as leaves, fruits, rhizomes, stems, legumes, nuts, and plant shoots, among others (Eliasson, 2004). Although these new sources have technological properties different from those already commercialized, many are still in the research phase, without studies of economic viability for industrial use. The selection of the extraction method depends on many factors, including origin, location in the plant, presence of nutrients, perishability after harvest, etc., which can vary from physical processes to the use of chemical reagents and enzymes. The principle of separation is based on the fact that starch is insoluble in cold water and has a proximate density of 1.5 g mL
1, which ensures its decantation when mixed with

Basic Principles: Composition and Properties of Starch

5

water (Eliasson, 2004). Therefore, processing plants for starch extraction and purification use great volumes of water and usually generate coproducts and wastes that require biological treatments. Further details will be discussed in Chapter 4. In some cases, starch is the main extraction product, as in the case of corn, cassava, and potatoes, but it is also considered a coproduct, for example, in the extraction of vital wheat gluten, which generates great amounts of starch rather than gluten, but with lower added value. The major goal of the extraction process is obtaining starch with a high degree of purity, while other nutrients (minerals, proteins, and lipids) should be at concentrations below 1.5 g  100 g
1. When starch meets the purity requirements, it is ready to be used in the native state or modified for use in the food processing industries (Tester et al., 2004). When starch is impure, the modifications will not be as effective, because other nutrients, such as proteins and lipids, are more reactive to chemical agents and physical processes than the starch itself, and impair the activity of amylolytic enzymes and reagents. Thus, in such cases, the modification technique requires an in-depth study to determine whether the reaction occurred with starch and/or another nutrient and whether the reaction led to changes in the protein crosslinking, the formation of toxic compounds, the formation of free radicals, or the Maillard reaction, among others. After extraction and purification, starch can be visually characterized as a fine white powder, insoluble in cold water, alcohol, ether, and other solvents, and soluble in dimethyl sulfoxide (DMSO). One way of identifying the presence of starch in food products is by the use of indicator dye, glycerin, or Lugol’s iodine, which will color in the blueered range (Brasil, 2010).

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Starches for Food Application

The identification of the source of extracted starch can be made by optical microscopy, since the starch granule presents distinct characteristics, such as birefringence under polarized light and presence of the Maltese cross, among others (Brasil, 2010). When viewed under an optical microscope, starch appears in the form of granules of varying sizes, shapes, and stratifications. The starch granule consists of a hilum (point of origin of the ring structure) and lamellae or striations (light and dark areas). The starch characteristics, including the spherical, ovoid, polyhedral, piriformic, and ellipsoid forms and size, can be detected by microscopic analysis, and a central point known as the hilum is observed in polarized light, which can be punctate, starry, linear, etc., followed by branching, forming the Maltese cross ( Jane, 2004, 2006). The form, granule size, and type of hilum or Maltese cross are good parameters to identify the most common starches from cereals, roots, and tubers, as can be seen in Table 1.1. Another important factor is that extracted starch can present different types of distribution (unimodal, bimodal, or trimodal). Table 1.1 shows an example of the bimodal distribution of the granule size in wheat, which may have different technological properties. When separated and analyzed alone, B starches (15%e20%) have a 2- to 15-mm diameter, while A-starch granules (80%e85%) are 20e35 mm, as reported by Jane et al. (1997). The formation of starch granules starts at the hilum and can be of three distinct kinds within the plastid, as follows: • simple: granule formed within the plastid, for example, potatoes, wheat, rye, etc.; • composite: more than one granule inside the plastid, for example, cassava, hazelnut, sweet potato, sago; • semicomposite: two or more simple granules, joined by the deposition of layers (Zobel and Stephen, 1996).

Table 1.1 Characteristics of some starches Starch Origin Size (mm)

Cereal

5e30

Wheat

Cereal

20e35 (A) 2e10 (B)

Rice Potato Cassava Barley

Cereal Tuber Root Cereal

3e8 5e100 4e35 2.3 (A) 7.5 (B) 20 (C) 10.2e13.6 (A) 2.1e3.1 (B) 13.9 (A) 4.06 (B)

Waxy barley

Cereal

Durum

Cereal

Distribution

Spherical/polyhedral with porous surface Lenticular (A type), spherical (B type) Polyhedral Lenticular Spherical/lenticular

Unimodal

Lenticular/spherical

Trimodal

Lenticular/spherical

Bimodal

Lenticular/spherical

Bimodal

Bimodal Unimodal Unimodal Unimodal

Adapted from Tester, R.F., Karkalas J., 2002. Polysaccharides. II. Polysaccharides from eukaryotes. In: Vandamme, E.J., De Baets, S., Steinbuchel, A., (Eds.), Starch in Biopolymers, sixth ed. Wiley-VCH, Weinheim, pp. 381e438; Tester, R.F., Karkalas, J., Qi, X., 2004. Starch-composition, fine structure and architecture. Journal of Cereal Science, 39, 151e165; BeMiller, J.N., Whistler, R.L., 2009. Starch: Chemistry and Technology, third ed. Academic Press, New York; Dendy, A.V.D., Dobraszczyk, B.J. (Eds.), 2001. Cereals and Cereal Products: Chemistry and Technology, An Aspen Publication, Gaithersburg.

Basic Principles: Composition and Properties of Starch

Maize

Morphology

7

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Starches for Food Application

1.3 CHEMICAL COMPOSITION OF STARCH As a fine powder, cereal starch contains about 10%e12% moisture, while tuber starch has 14%e15%. Maintaining this moisture value and using packaging to protect against variations in relative humidity are important factors for a longer storage of starch (years). The other nutrients should be in concentrations below 1.5%e2.0% in starch, as can be seen in Table 1.2. They occur in starches as follows: • Lipids in cereal starch granules may be internal, such as lysophospholipids and free fatty acids (FFAs), and external, as triglycerides, phospholipids, and FFAs, which may be from the amyloplast membrane; in other starches such as oat starch, the lipids may be complexed to amylose (Tester et al., 2004). • Proteins (max. 0.6%) may also be on the surface or internal as membrane proteins and enzymes responsible for the synthesis and degradation of starch (Tester et al., 2004). • Mineral salts are mainly represented by phosphorus, which may be phospholipids, monoesters, and inorganic phosphate. Native starches generally contain small phosphorus levels (0.1%). In the case of rootstocks, phosphorus is covalently bound to starch (Hogde et al., 1948), whereas in cereal starch, this mineral occurs mainly as phospholipids (Lim et al., 1994). As an example, the amount of phosphate groups in potato starch is in the range of 1 phosphate group per 200 to 400 glucose units, while the other starches have lower values (Swinkels, 1985). Pure starch is formed by glucose monomers linked by glycosidic bonds, being a homopolysaccharide. The way the glucose molecules are joined can be: • By a-1,4 glycosidic bonds with few a-1,6 branching points, forming the amylose molecule, which is essentially linear, with a molecular mass between 105 and 106 Da. Amylose has a great ability to form complexes with lipids due to its helical structure, and it may be free or complexed with lipids.

Protein

Ash

Phosphorus

Corn Regular Waxy High amylose Wheat Rice Potato Cassava

0.35 0.25 e 0.40 0.40 0.06 0.10

0.10 0.07 0.20 0.20 0.50 0.40 0.20

0.015 0.007 0.070 0.060 0.010 0.080 0.010

98.9 99.5 99.4e98.7 98.6 98.3 99.5 99.6

0.60 0.20 0.40e1.10 0.80 0.80 0.05 0.10

Adapted from BeMiller, J.N., Whistler, R.L., 2009. Starch: Chemistry and Technology, third ed. Academic Press, New York; Tester, R.F., Karkalas, J., Qi, X., 2004. Starch-composition, fine structure and architecture. Journal of Cereal Science, 39, 151e165; Eliasson, A.C., Gudmundsson, M., 2006. Starch: physicochemical and functions aspects. In: Eliasson, A.C. (Ed.), Carbohydrates in Food. CRC Press, New York, pp. 392e470.

Basic Principles: Composition and Properties of Starch

Table 1.2 Chemical composition of some starches, in percentage Starch Carbohydrate Lipid

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Starches for Food Application

• By a-1,4 glycosidic bonds with a large number of a-1,6 bonds, forming a branched structure, so-called amylopectin, with a molecular mass from 107 to 109 Da. Amylopectin unit chains are relatively short compared with amylose molecules, with a broad distribution profile. They are typically 18e25 units long on average. • By glycosidic bonds forming a small amount of intermediate material, from 5% to 7%, where the glucose molecules are in short or long branches, exhibiting different properties from amylose and amylopectin (Eliasson, 2004; BeMiller and Whistler, 2009; Bello-Perez et al., 2010). Amylose and amylopectin are radially arranged in the starch granule with their terminal reducing groups oriented toward the center or hilum, in which the deposition of these polymers takes place (Swinkels, 1985). These molecules are linked by hydrogen bonding, which maintains the integrity of the granule and establishes the physical strength and solubility, presenting differences in solubility and paste formation (gel), as can be seen in Table 1.3. When the starch granule is analyzed by X-ray diffraction, amorphous regions and semicrystalline regions are observed, which are characteristic of amylose and amylopectin, respectively. The elucidation of how these molecules are organized in the granule allowed advances in the studies on starch modifications, due to the difference in the reactivities of individual starch granules (Donald et al., 2001). The amylose and amylopectin contents vary according to the origin of the granule (Table 1.4). With the advances in the area of genetics, new modified starches can be obtained with the introduction of waxy genes, wx (recessive) and Wx (dominant), and ae genes (high amylose) into the plant. In this way, many plants present conventional starches and also waxy starches (above 85% amylopectin) and high amylose content (above 40% amylose). While the waxy starch is brittle, the

Table 1.3 Amylose and amylopectin characteristics Characteristic Amylose

10 e10 1500e6000 Unstable Variable Favorable Stiff, irreversible Coherent Blue 19%e20% Crystalline 100% 6

Amylopectin

107e108 3  105 to 3  106 Stable Soluble Unfavorable Soft, reversible d Red-purple 1% Amorphous 60%

Adapted from Ciacco, C.F., Cruz, R., 1982. Fabricação de amido e sua utilização. Secretaria de Estado da Indústria Comércio, Ciência e Tecnologia, São Paulo and Zobel, H.F., 1988. Molecules to granules: a comprehensive starch review. Starch/Starke, 40, 44e50.

Basic Principles: Composition and Properties of Starch

Molecular weight Degree of polymerization Dilute solutions Solubility Complex formation Gel Films Iodine color Iodine affinity Diffraction Digestibility (b-amylase)

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Starches for Food Application

Table 1.4 Amylose and amylopectin content of starches Starch Amylose (%) Amylopectin (%) Examples

Normal Waxy High amylose

20e35 18e25 37, with an average chain length of amylopectin of 18.75 (Sehn et al., 2012; Schmiele et al., 2015). It is known that a DP around 42 is a characteristic of the B2 chain, with chain length belonging to two clusters. The blue color formed by the amyloseeiodine complex is also used for the determination of the blue value (absorbance of 1% starch solution containing 2 mg iodine and 20 mg potassium iodide at 680 nm). The greater the linear chain length and the higher the amylose concentration, the more intense is the blue color. The blue value of starch granules is considered a qualitative test for amylose (Bertoft, 2004). Table 2.1 shows the blue values of some starch granules. The apparent amylose can also be measured by the iodine affinity, through potentiometric titration or with an automated amperemeter. The technique is based on the affinity of the a helix forming a blue complex with the iodine. On average, 20 mg iodine complexes with 100 mg amylose; therefore the apparent

32

Blue value Amylose content (%) 1

0.0594 25.50

Lii et al. (1995). Ogunmolasuyi et al. (2017). 3 Liang et al. (2017). 4 Saibene et al. (2008). 2

0.004 0.99

0.530 26.56

0.399 30.30

0.310 16.70

Sweet potato3

Corn4

0.447 34.40

0.400 21.30

Starches for Food Application

Table 2.1 Amylose content and corresponding blue value of various starches Waxy Pueraria Starch Rice1 Yam2 Potato4 rice1 root3

Identification and Analysis of Starch

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amylose concentration is given by the multiplication of iodine affinity by 5 (Takeda et al., 1987), since approximately 20 g of iodine is bound per 100 g amylose (Song and Jane, 2000). The determination of the apparent amylose may be affected by the amylopectin long chains, resulting in a false positive; thus the determination of absolute amylose can be performed as an alternative. For that, the starch is suspended in DMSO, followed by precipitation of amylopectin with lectin concanavalin A (a glycoprotein capable of complexing with some carbohydrates). After centrifugation, the amylose is hydrolyzed to glucose by the amylolytic enzymes, and the monosaccharide is quantified using the glucose oxidase/peroxidase reagent (GOPOD). Concanavalin A should be used with caution because of its toxicity. The absolute amylose can also be determined by fractionation of the amylose and amylopectin and subsequent evaluation of the iodine affinity of these fractions and the parent starch. The final calculation is made by the following formula: (Istarch  Iamylopectin)/(Iamylose  Iamylopectin)  100 (Song and Jane, 2000), where "I" means the iodine affinity. The most accurate techniques used for amylose quantification are based on high-performance size-exclusion chromatography (HPSEC), coupled to simultaneous refractive index and low-angle laser light scattering detection, or gelpermeation chromatography (GPC). However, in all these procedures, the amylopectin fraction remaining in the sample may be an interference factor. Thus, an alternative is the use of debranched enzymes, which will promote the hydrolysis of a-1,6 glycosidic bonds, releasing amylopectin short chains, and consequently improve the separation of longer amylose fractions. 2.3.1.2 Amylopectin The quantification of amylopectin can be performed after the amylose separation by enzymatic hydrolysis to release glucose, followed by GOPOD quantification. However, this information

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does not provide the amylopectin chain length, which is critical to the study of this fraction. In this regard, the most suitable method for determining amylopectin refers to the quantification of the number of chains of this macromolecule. For that, after amylose separation, the sample is subjected to total gelatinization and hydrolysis of the glycosidic bonds using the enzyme isoamylase. Then, the linear chains are quantified by high-performance anion-exchange chromatography with pulse amperometric detection (Wong and Jane, 1995; Moraes et al., 2013; Schmiele et al., 2015). Linear chains can also be identified by GPC or HPSEC and classified as A (DP 6e12), B1 (DP 13e24), B2 (DP 25e36), B3 (DP  37), and C (DP  100) chains (Hanashiro et al., 1996). NMR spectroscopy may be an alternative technique to study the amylopectin conformation, through the variations in 1H and 13C NMR (Nilsson et al., 1996; Zhang and Xu, 2017). It is a nondestructive technique; thus, it does not generate effluents and does not require enzymatic treatment.

2.3.2 Intermediate and Phytoglycogen Material In addition to amylose and amylopectin, starch granules also contain intermediate materials called glucans. These materials are more easily found in starch granules with high amylose content, mainly from potato, barley, and corn, and some types of peas, including those with a wrinkled appearance, in addition to oat, normal corn, wheat, and rye. However, the intermediate materials are not yet fully known and vary according to the starch source. In addition, they are heterogeneous and have structures similar to those of amylose, due to the iodine affinity (Bertoft, 2004), and amylopectin, due to the high average internal and external chain length (Han et al., 2017). Thus, the intermediate materials can be defined as a polymeric material formed by glycosidic linkages between glucose monomers, with a branched structure similar to amylopectin and amylose chain length (Li et al., 2008).

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These intermediate materials probably originate from immature clusters formed by the enzyme granule-bound starch synthase, which is responsible for the formation of amylose (Hanashiro et al., 2008), in synergy with the starch synthases and starch branching enzymes and debranching enzymes (Wang et al., 2017), resulting in the cleavage of the amylose chain and the transfer of chains to an amylopectin molecule. However, this phenomenon has not yet been confirmed experimentally (Vilaplana et al., 2014). The quantification of intermediate materials of cereal starch was performed through the dispersion/solubilization of starch in DMSO and subsequent separation of amylose and amylopectin. This fractionation was obtained by the complexation phenomena between amylose and the intermediate materials and thymol (a phenolic compound belonging to the terpene group), with precipitation and separation of amylopectin. Then, amylose was reprecipitated in butanol, with the intermediate material consisting of anomalous amylose and/or long-chain amylopectin remaining soluble (Banks and Greenwood, 1967). Similarly, the primary precipitation of amylose with 1-butanol was also carried out, followed by precipitation of the intermediate materials with iodine from the amylopectin fraction, showing that the higher the amylose content, the higher the intermediate material concentration (Adkins and Greenwood, 1969). To improve the separation of the components, Wang et al. (1993) used GPC on Sepharose CL-2B, and identified smaller branched components, rather than amylopectin, at different concentrations depending on the starch source. A blend containing 6% 1-propanol and 6% isoamyl alcohol can also be used to separate the amylose and amylopectin from the intermediate material. These methods confirm that although the intermediate materials have characteristics similar to those of amylopectin, they are capable of precipitating with 1-butanol, like amylose. In addition, the regular branched

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structure of the intermediate materials may exhibit partial inhibition of enzymatic hydrolysis, thereby reducing the starch digestion rate (Bertoft et al., 2000), for this characteristics the starch digestion can be classified as rapidly digestible starch, slowly digestible starch and resistant starch based on enzymic digestion in vitro(topics that will be covered in more detail in Chapter 8). A water-soluble polysaccharide can also be found in the starch fraction, especially in the sugarye1 mutants of maize and rice endosperm. This component is called phytoglycogen and presents glucose as a monomer and a DP of w10, with internal branches with DP between 7.0 and 8.0 and extremely short external branches with DP w3.0 (Jane, 2009).

2.4 MORPHOLOGICAL AND STRUCTURAL CHARACTERIZATION 2.4.1 Polarized Light Microscopy Optical microscopy allows the evaluation of starch characteristics in relation to the shape, size, and distribution of the granule from different plant sources (Van de Velde et al., 2002). When a polarized lens is used, the Maltese cross can be seen under the polarized light when starch has not undergone gelatinization. As soon as the starch undergoes heating in the presence of water, birefringence end-point temperature (BEPT) loss is observed. This is a simple test with good sensitivity. The loss of birefringence occurs over a wide temperature range (10e15 C). However, there is a good relationship between BEPT and differential scanning calorimetry (DSC) analysis for starch granules from different plant sources (Biliaderis, 2009).

2.4.2 Scanning Electron Microscopy Surface images are extremely important for studying starch granules. The first techniques involved scanning probe microscopy,

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AFM, and scanning tunneling microscopy. The image resolution was improved with the advent of SEM. Starch is a nonconductive material, which is a limiting factor; thus the use of metals (gold or platinum) in coating the surface of biological material minimizes this limitation. The technique is performed within a vacuum chamber, which may partially modify the surface of the starch granules, which can be prevented by using moderate vacuum. This new method is called environmental SEM and is widely used both for the study of plant genetic development (Stabentheiner et al., 2010) and for high-moisture samples (Roman-Gutierrez et al., 2002). The SEM technique presents the best image resolutions of dehydrated samples. When water removal is not possible or the matrix can be altered by drying, the temporary immobilization of the aqueous phase (freezing) is important to allow cryo-SEM imaging. In this technique, although the image resolution is lower, it is an alternative when studying the swelling power, water absorption, amylose leaching, retrogradation phenomenon (Matignon and Tecante, 2017), and stability of emulsions or nanoemulsions using modified starch as emulsifiers (Zhang et al., 2016; Chiu et al., 2017). High-quality images can be obtained by low-voltage SEM, as the onset of low-voltage electrical current promotes lower heating rates (Pérez et al., 2009; Huang et al., 2017). SEM also allows the study of the surface characteristics (smooth or porous), particle size, and format (polyhedral, oval, flattened, hexagonal) and whether the starch is unimodal, bimodal, or trimodal.

2.4.3 Confocal Laser Scanning Microscopy Confocal microscopy allows the evaluation of the twodimensional (2D) or three-dimensional (3D) topography of starch through high-resolution images using chromophore compounds with fluorescence properties, allowing a detail

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evaluation of surface area and depth. In addition, it is possible to identify how amylose is uniformly distributed in the starch granule ( Jane, 2009). The presence of other components is also possible through the use of chromophores, also known as dyes or markers, which form complexes with specific components of the material to be evaluated, with proteins (3-(4-carboxybenzoyl)quinoline2-carboxaldehyde or fluorescein isothiocyanate), lipids (Nile red, 5-hexadecanoylaminofluorescein, fluorescein octadecyl ester), and carbohydrates (rhodamine B) (Han and Hamaker, 2002; Achayuthakan et al., 2012). A wide range of dyes have also been used with promising results. This technique has been widely used to evaluate the interaction between starch granules and various components, including hydrocolloids such as xanthan gum (Gonera and Cornillon, 2002), gum acacia, and dextran (Achayuthakan et al., 2012); proteins such as gelatin, whey protein, and soy protein isolates; and lipids (Davanço et al., 2007; Matignon et al., 2014).

2.4.4 Atomic Force Microscopy AFM has been used to observe the nanoscale of the structure of starch granules from different plant sources. Baldwin et al. (1996), Baldwin et al. (1997), Baker et al. (2001), and Ridout et al. (2002) observed a blocklet structure, which has been studied by Gallant et al. (1997). AFM allows the observation that the size of the blocklet structure can vary according to the starch granule. For example, the surface of native wheat starch had small protrusions of 10e50 nm, while potato starch exhibited larger spherical protrusions of 200e500 nm (Baldwin et al., 1996, 1997). According to Ridout et al. (2002), the AFM images of the growth rings and the blocklet structures of native potato and maize starch, unstained starch, and unmodified starch were affected by the embedding resin used. They authors also found similar results and reported that the fixation techniques can lead to possible unintended reactions with the embedding resin such

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as epoxy resins or adhesives. Other authors reported modifications in obtaining the images, as follows: • Szymonska and Krok (2003) performed AFM studies on starch granules by high-resolution noncontact AFM, which did not affect the sample surface, and observed the blocklet model of potato starch granules subjected to multiple freezing and thawing. They observed surface subparticles that might correspond to single amylopectin side-chain clusters bundled into larger blocklets packed in the lamellae within the starch granule. • Park et al. (2011) developed a novel AFM protocol, using starch subjected to iodine vapor under humid conditions. They found vertical fiberlike structures, which were extensions of the glucan polymers from either amylose or amylopectin that were free to complex with iodine in the presence of moisture. In addition, they reported that the morphology and location of the hairlike extensions were different in corn and potato starches, likely reflecting the organization of polymers within the granule. The advancement of AFM images can provide new findings, such as chemical, enzymatic, and physical modifications in the native granule and interactions between starch granules and other compounds, including the studies of: • Dimantov et al. (2004), who studied films obtained with a blend of pectin and high amylose maize starch by AFM, and found increased roughness with the increase in starch concentration in the films; • Simão et al. (2008), who found growth rings in starch granules during the ripening of mango.

2.4.5 Differential Scanning Calorimetry DSC is a technique that evaluates the changes in starch granules in relation to the molecular mobility and the ordering/disordering processes during heating and cooling. It is widely used to evaluate several factors, including temperature, heating,

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degree of gelatinization, glass transition, structural organization of starch, and melting and crystallization of starch components (important for the retrogradation measurement), among others, such as resistant starch type II (naturally present) and resistant starch type V (amyloseelipid complex) (Pérez et al., 2009). In general, the determination is made by measuring the temperature difference between the sample placed in a hermetically sealed container and an empty container referred to as a reference. The lower the variation between the beginning and the end temperatures of the thermal event, the greater the organization of the starch structure. Then, the parameters gelatinization temperature (Ton ¼ onset temperature), final gelatinization temperature (Tend), temperature variation (between Tend and Ton), and gelatinization enthalpy (area under the curve; J g1) are obtained, as you can see in Fig. 2.1. The glass transition is one of the most important parameters for the study of the properties of amorphous or partially crystalline polymers, changes in the mechanical properties, the behavior of the material during the processing, and the stability.

2.4.6 Nuclear Magnetic Resonance NMR is a qualitative and quantitative method, which shows the shape and structure of the molecules, and its most important application is in the study of hydrogen atoms in organic

Figure 2.1 Differential scanning calorimetry curve for maize starch.

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molecules. The hydrogen atom is perhaps the easiest to understand from the point of view of its physical properties (Robinson, 1995). For starch analysis, the following isotopes are used: 1H, most used and distinguishing H from a-1,4 and a-1,6 glycosidic bonds; 13C, distinguishing C associated with the nonreducing endings; and 31P, indicating the phosphodiester crosslinks in naturally occurring or chemically modified starches. NMR has been used to evaluate the formation and localization of new functional groups in modified starches, for example, the carboxyl groups found in oxidation processes. Teleman et al. (1999) showed that the hypochlorite oxidation of potato starch occurred at positions C-2 and C-3 of a glucose unit, and the introduced carboxyl groups caused ring cleavage between carbons C-2 and C-3. The authors studied anion-exchange chromatography after enzymatic hydrolysis to isolate the pentamer and hexamer containing one glucose unit, which was oxidized to a dicarboxyl residue, and further evaluated through 1H and 13C NMR spectroscopy. NMR has been used along with other techniques to evaluate physical, chemical, and enzymatic modifications; type of starch; behavior during cooking; and retrogradation, among others.

2.4.7 X-ray Diffraction X-ray diffraction has been used to determine the crystalline structure and extent of starch granules, aimed at knowing their plant origin. Starch granules are analyzed in the native form, and the crystalline pattern may change or even disappear in cases of modification reactions. The degree of crystallinity of the native starch ranges from 15% to 45% (Cheetham and Tao, 1998) and it is directly related to the amylopectin content and chain length, and inversely proportional to the amylose content (Hoover, 2001).

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The X-ray diffraction patterns of starch granules are classified according to the packing of the double amylopectin helices and present basically four types: A, B, C, and V. The A-type structure is associated with cereal starches (maize, rice, wheat, and oat), while the B type is associated with root and tuber starches (potato, cassava), except for starch with high amylose and amylopectin contents, and modified starches (Cheetham and Tao, 1998; Eliasson, 2006). The C-type structure is formed by the mixture of A and B types, representing legume starches (beans, peas) and some mutant starches, with A type around the pericarp and A type in the center of the bead (Buleon and Colonna, 2007). The C type can also be subclassified into Ca, Cb, and Cc, according to its similarity with A type and B type. The V type is associated with lipid-containing gelatinized starches (Eliasson, 2006) or emulsifiers, butanol, and iodine (Cheetham and Tao, 1998). It is still possible to find the E-type structure in extruded starch under different humidity and temperature conditions (Vandeputte et al., 2003). These crystallinity patterns can also vary according to the size of the amylopectin chain; shorter chains (CL  19.7) favor the formation of A-type crystals, longer chains (CL  21.6) favor the B-type structure, while the association between the intermediate chains leads to the formation of C-type crystals (Hizukuri et al., 1983). This behavior was also observed by Cheetham and Tao (1998), who studied maize starch with different amylose and amylopectin levels and found an increase in crystallinity with increasing amylopectin content (Eliasson, 2006). Diffraction methods and calculation of the crystalline region have been reported by Srichuwong et al. (2005), Tester et al. (2004), Nara and Komiya (1983), Rocha et al. (2008), and Hayakawa et al. (1997).

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2.4.8 Fourier-Transform Infrared Spectroscopy Infrared (IR) radiation is electromagnetic radiation with longer wavelengths than those of visible light and extends from the nominal red edge of the visible spectrum at 780 up to about 50 mm. The main objective of IR spectroscopy is to qualitatively evaluate the presence of functional organic groups, such as carboxyls, carbonyls, and hydroxyls, as each group absorbs a characteristic radiation frequency in the IR region. After the sample is analyzed in the spectrometer, a graph gives the intensity of the emitted radiation per frequency, which will allow characterizing the functional groups of a standard or an unknown material. The IR spectra, together with other spectral data, are useful for determining the molecule structure since each compound has a typical identity, which can be compared with known compounds and free database software. When the quantification of the functional groups is necessary, the analysis is done using near-IR spectroscopy, with evaluation of the bands characteristic in the fingerprint region from 1350 to 910 cm1. In addition to evaluating the presence of other compounds by the identification of functional organic groups, Fourier-transform IR (FTIR) spectroscopy can be used to evaluate the chemical modifications of starch granules. Demiate et al. (2000) evaluated chemically oxidized cassava starch, commercial cassava sour starch, and native cassava starch by FTIR spectroscopy associated with chemometric data processing and qualitative and quantitative spectral analyses. The authors found the presence of carboxylate groups (1600 cm1) on cassava starch as well as some other changes in the region around 1060 cm1, and concluded that degradative oxidation is assumed to take place on the CeO bond relative to carbon 1 and oxygen 5 of the cyclic part of glucose at 1060 cm1.

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2.5 RHEOLOGICAL CHARACTERIZATION The rheological properties describe the behavior of materials subjected to shearing forces and deformation, which are considered viscoelastic complexes (Alcázar-Alay and Meireles, 2015). Rheological measurements were initially performed in a rheometer, obtaining the information of storage modulus (G0 ), which indicates the elastic behavior of starch; loss modulus (G00 ), which describes the viscosity behavior; and tan d (G00 /G0 ), indicating liquidlike (>1) or solidlike (55% amylose) (Gunaratne and Corke, 2004). Several factors can affect the swelling power, including: • Amylose and amylopectin ratio: Higher amylopectin contents lead to increased swelling (Ross, 2012). For example, waxy rice starches subjected to high gelatinization temperatures show high swelling power at 80 C, with low solubility in relation to waxy starch at low gelatinization temperatures (Tester and Morrison, 1990b).

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• Formation of the amyloseelipid complex: This inhibits the swelling process and solubility (Tester and Morrison, 1990a). • Occurrence in the granule: In some starch granules, such as potato and maize, the granule seems to swell to a similar degree in all directions, while wheat, rice, and barley starches swell in only one direction (Eliasson and Gudmundsson, 2006). • Size: Cassava starch, which presents larger granules, has a greater swelling power (35.6 g/g) compared with rice starch, which presents small granules (15.7 g/g) (Hamzah and Hill, 2010). • Morphological structure: For example, potato starch has a poorly compacted structure and presents swelling power at room temperature, which is not observed for maize starch, which has a compact structure (Fonseca-Florido et al., 2017). • Presence of other functional groups rather than hydroxyl groups: Potato starch showed high swelling power and solubility compared with root and tuber starches, such as cassava and yam, probably due to the presence of phosphate, which contributed to hydration due to the repulsion to amylopectin (Hoover, 2001). • Starch modifications: Changes in pH and physical modifications such as annealing processes (Adebowale and Lawal, 2002) and heatemoisture treatment (Hormdok and Noomhorm, 2007) can affect swelling power. Tester and Morrison (1990a) evaluated the swelling power of native and waxy starches from wheat, barley, and corn, and observed that the onset of swelling was close to the initial gelatinization temperature (Ton) previously determined by DSC. A great exposure to high temperatures did not affect the swelling power, which increased with an increase in water:starch ratio (above 2.5:1). Other factors that may contribute to the increase in swelling power and solubility include defatting and greater agitation during heating, since the amyloseelipid complex acts as an inhibitor of this process, not being leached,

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with dissociation only above 94 C. A mild agitation can increase the swelling power, while a high agitation leads to the disintegration of the granules (Eliasson and Gudmundsson, 2006). The swelling and solubility properties are of industrial importance, as they provide important information on starch behavior in different food production systems. Factors such as the space occupied by starch, the loss of solids from suspensions or starch pastes, and the fluid flow during the various unit operations, such as filtration and transport through the pipes, must be taken into account, in addition to starch-containing products packaged before heat treatment, among others (Lapasin and Pricl, 1995). Another important factor is the selection of the packaging material, since packaging with high permeability to water vapor, such as sacks, can lead to an increase in the specific volume of raw starch, including potato starch, in addition to reducing the shelf life of the product when stored in regions of high relative humidity.

2.6.2 FreezeeThaw Stability Knowledge about the starch stability during the freezeethaw cycle is important to maintain the sensory quality of refrigerated and frozen products. This information will be useful for products for direct consumption or for those products containing gelatinized and retrograded starch that will be subjected to further processing operations. According to Vamadevan and Bertoft (2015), these cycles may lead to water exudation (syneresis) due to the reassociation of the starch molecules. Three methods can be used to verify the starch stability: measurement of the syneresis content, which is dependent on the centrifugal force applied to the sample; rheological characterization using a rheometer (Eliasson and Gudmundsson, 2006); and DSC analysis (Vamadevan and Bertoft, 2015). Native starches present low freezeethaw stability (Eliasson and Gudmundsson, 2006), with the exception of oat starch,

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which exhibits extensive retrogradation during the freezeethaw cycles (Chotipratoom et al., 2015); thus chemical substitutions, genetic modifications, and the use of hydrocolloids can reduce the quality loss of the starch gel (Vamadevan and Bertoft, 2015). Some authors have studied starch stabilization, including: • Use of hydrocolloids: Lee et al. (2002) evaluated the stability of sweet potato starch gels submitted to five freezeethaw cycles, using several types of gum, and found that sodium alginate, guar gum, and xanthan gum were effective in reducing syneresis. • Use of starch modification processes: • Ye et al. (2016) observed that extruded rice starch showed greater stability in the freezeethaw cycle than the native starch. • The use of high-pressure hydrostatic technology combined with propylene oxide at different concentrations (4, 8, and 12% v/w) applied in maize starch led to better stability for the higher concentration (12%) at 400 MPa, which prevented adequate chain realignment, which could lead to retrogradation (Chotipratoom et al., 2015).

2.6.3 Other Methodologies Methods for measuring gel strength, opacity, and clarity of the starch gel are also important for starch characterization. Paste clarity can be determined by the percentage transmittance from a dilute solution of starch (1% w/w) to a wavelength of 650 nm. Tuber starch forms clear pastes and has larger transmittance compared with cereal starch, which forms less clear pastes (Craig et al., 1989). This analysis is important for confectionery using cereal starch as cake fillings. For toppings, such as fruit fillings, preference is given to tuber starch, since the pastes are clear and present lower retrogradation rates. The paste clarity can vary according to the origin of starch, type of modification, and storage time.

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The gel strength or gel resistance is determined using a texture analyzer, in which the parameter peak force (N) defines the resistance of the 3D network (Ulbrich et al., 2015). It has been used to evaluate retrogradation and is very important for ready-to-eat starchy products, since the starch gel must withstand storage and transport conditions.

2.7 NUTRITIONAL CHARACTERIZATION In its natural granular state (raw), starch degradation by enzymes is difficult; however, when cooked, it becomes an important source of energy in the diet, since it is hydrolyzed by amylases in maltose, dextrins, and maltotriose, which in turn will be hydrolyzed by the oligosaccharidases in glucose and then absorbed in the intestine ( Jane, 2004). Although amylases are found in both the saliva and the intestine, the highest starch hydrolysis occurs in the intestine. In vivo and in vitro studies can also be carried out with the use of enzymes to characterize starch from various sources. In vitro methods are preferable since they do not require ethics committee approval, which is necessary for in vivo studies using humans and animals. The classical method of assessing in vivo glycemia in humans, under fasting conditions or through the glycemic curve, has been used for medical purposes. However, owing to the different health conditions of individuals, the evaluation of starch digestibility in humans is limited to groups of research related to the health field. The methods used to evaluate starch digestibility simulate a complete digestive process in vitro, in which starch is subjected to pH conditions and digestive enzymes that vary according to the human intestinal transit, thus simulating the gut environment. Starch is then classified according to its digestion rate and whether or not it is digested; the undigested starch is called resistant starch.

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It is worth noting that resistant starch has a nutritional function similar to that of dietary fiber; thus the evaluation methods may be specific, such as those reported by Englyst et al. (1992), Goni et al. (1997), and AOAC (2006), or determined in food as dietary fiber. Starch digestibility varies according to the interactions that occur during food processing, since there is a tendency toward a lower digestion rate when complexed with lipids, fibers, and proteins, which is determined by the glycemic curve for 120 min or more. Although the methods in vitro do not reflect the reality of the digestive process in vivo, they provide preliminary information that guides the development of slow and resistant starch quickly and at a lower cost, in addition to the possible interactions with nutrients in the final product.

2.8 BIODEGRADATION OF STARCH-BASED PACKAGES Packaging containing polymer compounds and edible starch-based films are evaluated for their biodegradation in the environment. Mergaet et al. (2000) and Accinelli et al. (2012) used the Lugol solution to evaluate the biodegradation of starch-based packaging and verified the blue zone clearing (starcheLugol complex) over time, since the starch was used by the soil microbiota under study.

2.9 FUTURE TRENDS With the greater concern about the preservation of the environment and the safety of laboratory analysts, the reduction or elimination of the use of chemical reagents has been widely discussed. Microscale analytical techniques have been used for those situations requiring chemical reagents.

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The use of green chemistry in nondestructive analytical techniques is an increasing demand, allowing the elimination of the generation of effluents (nontoxic or toxic), obtaining the results in a fast, safe, and reliable way. However, these techniques require highly qualified technicalescientific knowledge, mainly concerning the interpretation of the results. Other more recent starch evaluation techniques include the use of biosensors, crystallographic techniques, flow fieldeflow fractionation coupled to multiangle light scattering, refractive index detectors, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, sonic spray ionization, and distributed expert systems, among others.

2.10 CONCLUSION Classical or modern techniques to evaluate starch granules, whether gravimetric, colorimetric, potentiometric, titrimetric, or well-established instrumental or empirical methods, are of fundamental importance to the food and nonfood industries. The physicochemical, morphological, structural, rheological, and nutritional characterization allows one to identify starch properties such as plant origin, adulteration, behavior during food processing, and sensory and nutritional properties.

REFERENCES AACCI, 2010. Approved Methods of the American Association of Cereal Chemists International. American Association of Cereal Chemists, St. Paul. Accinelli, C., Saccà, M.L., Mencarelli, M., Vicari, A., 2012. Application of bioplastic moving bed biofilm carriers for the removal of synthetic pollutants from wastewater. Bioresource Technology 120, 180e186. Achayuthakan, P., Suphantharika, M., BeMiller, J.N., 2012. Confocal laser scanning microscopy of dextranerice starch mixtures. Carbohydrate Polymers 87, 557e563. Acosta-Osorio, A.A., Herrera-Ruiz, G., Pineda-Gómez, P., CornejoVillegas, M.A., Martínez-Bustos, F., Gaytán, M., et al., 2011. Analysis

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of the apparent viscosity of starch in aqueous suspension within agitation and temperature by using rapid visco analyser system. Mechanical Engineering Research 1 (1), 110e124. Adebowale, K.O., Lawal, O.S., 2002. Effect of annealing and heat moisture conditioning on the physicochemical characteristics of Bambarra groundnut (Voandzeia subterranea) starch. Nahrung Food 46 (5), 311e316. Adkins, G.K., Greenwood, C.T., 1969. Studies on starches of high amylose-content. Part X. An improved method for the fractionation of maize and amylomaize starches by complex formation from aqueous dispersion after pretreatment with methyl sulphoxide. Carbohydrate Research 11 (2), 217e224. Ai, Y., Hasjim, J., Jane, J., 2013. Effects of lipids on enzymatic hydrolysis and physical properties of starch. Carbohydrate Polymers 92 (1), 120e127. Alcázar-Alay, S.C., Meireles, M.A.A., 2015. Physicochemical properties, modifications and applications of starches from different botanical sources. Food Science and Technology 35 (2), 215e236. Alexander, R.J., 1995. Potato starch: news prospects for an old product. Cereal Foods World 40 (10), 763e764. AOAC, 2006. Approved Methods of the American Association of Offical Analytical Chemists. American Association of Offical Analytical Chemists, Gaithersburg, USA. Baker, A.A., Miles, M.J., Helbert, W., 2001. Internal structure of the starch granule revealed by AFM. Carbohydrate Research 330, 249e256. Baldwin, P.M., Frazier, R.A., Adler, J., Glasbey, T.O., Keane, M.P., Roberts, C.J., et al., 1996. Surface imaging of thermally-sensitive particulate and fibrous materials with the atomic force microscope: a novel sample preparation method. Journal of Microscopy 184, 75e80. Baldwin, P.M., Davies, M.C., Melia, C.D., 1997. Starch granule surface imaging using low-voltage scanning electron microscopy and atomic force microscopy. International Journal of Biological Macromolecules 21, 103e107. Banks, W., Greenwood, C.T., 1967. The fractionation of laboratoryisolated cereal starches using dimethyl sulphoxide. Starch/Stärke 19 (12), 394e398. BeMiller, J.N., Whistler, R.L., 2009. Starch: Chemistry and Technology, third ed. Academic Press, New York. Benavent-Gil, Y., Rosell, C.M., 2017. Morphological and physicochemical characterization of porous starches obtained from different botanical sources and amylolytic enzymes. International Journal of Biological Macromolecules 103, 587e595.

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Zaidul, M.I.S., Norulaini, N., Mohd. Omar, A.K., Yamauchi, H., Noda, T., 2007. Correlations of the composition, minerals, and RVA pasting properties of various potato starches. Starch/Stärke 59 (6), 269e276. Zhang, G., Hamaker, B.R., 2003. A three component interaction among starch, protein, and free fatty acids revealed by pasting profiles. Journal of Agricultural and Food Chemistry 51, 2797e2800. Zhang, Y., Xu, S., 2017. Effects of amylose/amylopectin starch on starchbased superabsorbent polymers prepared by g-radiation. Starch/Stärke 69 (1e2). Zhang, J., Bing, L., Reineccius, G.A., 2016. Comparison of modified starch and Quillaja saponins in the formation and stabilization of flavor nanoemulsions. Food Chemistry 192 (1), 53e59. Zhu, F., 2015. Impact of ultrasound on structure, physicochemical properties, modifications, and applications of starch. Trends in Food Science and Technology 43 (1), 1e17.

FURTHER READING Manan, A., et al., 2001. Effect of temperature and starch concentration on the intrinsic viscosity and critical concentration of sago starch (Metroxylon sagu). Starch 90e94.

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CHAPTER 3

Cereal Starch Production for Food Applications Edith Agama-Acevedo, Pamela Celeste Flores-Silva, Luis Arturo Bello-Perez Centro de Desarrollo de Productos Bióticos del Instituto Politécnico Nacional, Yautepec, Mexico

Contents 3.1 Starch Overview 3.1.1 Starch Components 3.2 Starch Production and Modification 3.2.1 Isolation Process 3.2.2 Starch Modification 3.3 Physicochemical and Functional Properties 3.3.1 Gelatinization 3.4 Starch Digestibility 3.5 Food Applications 3.6 Final Remarks References Further Reading

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3.1 STARCH OVERVIEW Starch is classified among the three more abundant polysaccharides in the nature, together with cellulose and chitin. Nevertheless, only starch is used as the main storage carbohydrate of green plants, whereas cellulose and chitin are structural polysaccharides. Starch is accumulated in organelles named amyloplasts and stored for a long time; then it can be used by the seed during the sprouting process, e.g., cereals, or it can be maintained in other tissues (e.g., seed, tuber, unripe fruit, etc.) and provides diverse Starches for Food Application ISBN 978-0-12-809440-2 https://doi.org/10.1016/B978-0-12-809440-2.00003-4

© 2019 Elsevier Inc. All rights reserved.

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functionalities to the products made with those starchy sources. Starch can also be isolated and applied as an ingredient in different items, e.g., foods, drugs, cosmetics, plastics, adhesives, paints, etc. The food industry is the main sector (61%) where starch is used as ingredient to give functionality at the products (Fig. 3.1); additionally, many foods (e.g., bakery products, pasta, tortilla, cooked rice, cooked potato, etc.) are prepared with starchy materials because starch provides desirable functional and nutritional characteristics. Maize, potato, wheat, rice, and cassava are the main commercial sources for starch isolation, but cereals are the main raw material for starch isolation with this purpose. The use of starch in the aforementioned products is mainly to impart physicochemical and functional characteristics such as water retention, viscosity, gel formation, etc. However, the functionalities of native starch are restricted and it should be modified by chemical, physical, or enzymatic methods to overcome those drawbacks. The functionality and nutritional features of starch are due to two main components in the granule structure: amylose and amylopectin. In general, the granule size of cereal starches Other Non-food 5%

Corrugating and paper 29%

Feed 1%

Confectionery and drinks 31%

Other food 30% Pharma & Chemicals 4%

Figure 3.1 Main starch applicationsd2015. (Data from Starch Europe, n.d. Retrieved from: http://www.aaf-eu.org; https://www.starch. eu/european-starch-industry.)

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ranges between 3 and 25 mm, with round and oval shapes. Two granule populations have been reported in cereal starches; the first is a population named A granules, with small size (3e6 mm), and the second is a population named B granules, with larger size (10e25 mm). The two populations differ in the content of minor components (protein, lipid, and ash content) and in physicochemical and functional properties (pasting profile, gelatinization temperature) (Seib, 1994; Tang et al., 2001; Ao and Jane, 2007; Maningat et al., 2009). The chemical composition of native and modified starches can define some characteristics. For instance, the lipids in cereal starches (e.g., maize and rice) can complex with amylose and alter the functional, physicochemical, and digestibility features of those starches. Moreover, residual protein can produce undesirable characteristics in syrups, due to Maillard reactions during the elaboration step. In this sense, it is important to keep in mind that the physicochemical, functional, and digestibility features of cereal starches are an “average” of the characteristics of both populations and the granule size distribution is a variable that is important to consider in starch end use. Cereal starches show pores and channels as evidenced by scanning electron microscopy or when they are hydrolyzed on the surface by a-amylase. Pores and channels in cereal starches are related to starch biosynthesis as they can be used by biosynthesis enzymes to produce growth of starch components. Also, pores and channels can be useful during chemical modification as the reagents can penetrate inside the granule and increase the reaction efficiency (Huber and BeMiller, 2000).

3.1.1 Starch Components The basic unit of the starch components (i.e., amylopectin and amylose) is glucose; therefore, starch is classified as a homopolysaccharide. Amylose is considered an essentially linear polymer, in which glucose units (GUs) are joined by a-1,4 linkages. Although some branching points are present, they are

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limited and hence do not change its behavior as a linear polymer. In the granule structure arrangement, amylose is found in the amorphous lamellae. The other component, amylopectin, is a branched material of GUs joined by a-1,4 linkages in the linear chains and by a-1,6 linkages in the branching points. Amylopectin constitutes the crystalline lamellae of starch and their branching points are in the amorphous lamellae. The amorphous and crystalline lamellae in the starch granule confer on this biopolymer a semicrystalline nature. Amylose and amylopectin are ordered in concentric rings as evidenced by confocal and atomic force microscopy. It has been suggested that amylose is mixed with amylopectin in the branching points of the “cluster” model, although alternative models have been also proposed (Perez and Bertoft, 2010). Also, a surface gelatinization study suggested that amylose is centralized in the periphery of the granule (Jane, 2007). Although advances in the granule structure have been obtained, the exact location of amylose and the nature of the amorphous regions in the starch granule are still not well understood (Wang and Copeland, 2013). In general, amylose constitutes around 25%e30% and amylopectin around 70%e75% of the granule starch, in which case they are usually called “normal” starches. Some starches present a high amylopectin level (98%e99%) and are named “waxy,” and others have high amylose content (50%e70%), e.g., Hylon maize starches. The amylose:amylopectin ratio is related to the physicochemical and functional characteristics of starch; e.g., waxy starches present high viscosity and low tendency to retrogradation, and high-amylose starches show high resistance to breakdown by digestive enzymes, high tendency to retrogradation, and formation of amyloseelipid complexes (Hasjim et al., 2010). The molecular structure of starch, which means the arrangement of starch components (amylose and amylopectin) in the granule of both native and modified starches, is also reported as an issue of its functional and physicochemical characteristics.

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The “blocklet” structure in the granule was evidenced by atomic force microscopy analysis, whereby small protrusions with size between 10 and 50 nm were observed on the surface of native wheat starch granules (Baldwin, 1995). “Nanocrystals” can be obtained during acid hydrolysis of the starch molecular structure, and they are preferentially prepared from waxy maize starch. Starch nanocrystals can be used for the reinforcement of starch films and to stabilize emulsions because of its small size, on the nanometer scale (Angellier et al., 2004; Dufresne, 2014). The chain-length distribution of amylopectin was suggested as an important characteristic to explain the physicochemical and functional characteristics of starch; it was reported that small differences in the chain-length distribution (Bertoft et al., 2016), molecular weight, and gyration radius (Bello-Perez et al., 2017) can explain differences in physicochemical, functional, and digestibility characteristics. Cereal starches present high amount of short chains (A chains) in the “cluster” model (Paredes-Lopez et al., 1994; Imberty et al., 1987), which was related to a slow digestion feature (Zhang et al., 2006a). Nevertheless, a parabolic model in which a high level of long chains (B chains) is present in the amylopectin structure can also produce similar digestion characteristics (Zhang et al., 2006b). Hence, more research is still necessary for further understanding the relation between digestibility and starch structure. The aforementioned characteristics of starch granules (shape and size, amylose:amylopectin ratio, amylopectin chain-length distribution, and starch components arrangement [matrix]) are involved in their functionality and digestibility. For example, waxy rice starch (small granule size) and a high level of short chains in the amylopectin is preferred to prepare a cover solution for canned mushrooms to maintain the turgor during storage; also, cereal starches with a high amount of short chains show slow digestion properties (Zhang et al., 2006a,b).

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3.2 STARCH PRODUCTION AND MODIFICATION Starch is one of the most multifunctional materials used in the industry, due to its many different technological functions. In 2012, 75 million tons of starch was produced worldwide (Agrana Research & Innovation Center), which is expected to increase, as the global starch market is projected to reach 182 million metric tons by 2022 (Global Industry Analysts). At this writing, the United States is the main starch producer, followed by the European Union (EU) (Waterschoot et al., 2015). However, The AsiaePacific region is the largest and fastest growing market worldwide, due to their favorable economic climate, growing population, robust food processing industry, and expanding manufacturing sector (Global Industry Analysts). Starch application depends on its specific physicochemical properties, which are strongly correlated with its botanical origin. Among cereal starches, maize (Zea mays L.) and wheat (Triticum spp.) represent 99% of the global starch production (Fig. 3.2). Other small-production cereal starch sources are rice, barley, rye, sorghum, quinoa, and amaranth (Waterschoot et al., 2015). In the United States and the EU, most of starch Rice starch 0% Wheat starch 9%

Maize starch 91%

Figure 3.2 Estimated world production of cereal starches. (Based on Waterschoot, J., Gomand, S.V., Fierens, E., Delcour, J.A., 2015. Production, structure, physicochemical and functional properties of maize, cassava, wheat, potato and rice starches. Starch Starke 67, 14e29.)

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produced is utilized directly as an ingredient or for conversion to other products and it is derived by the wet-milling processing of maize kernels (Global Industry Analysts; Starch Europe). Starches are marketed as native, physically or chemically modified, and also as liquid and solid sweeteners (Waterschoot et al., 2015). The global demand for starch-based sweeteners is high because it is closely related to the soft drink industry. According to Starch Europe, of the 9.3 million tons of starch and starch derivatives consumed in the EU, 55% are starch sweeteners (Fig. 3.3), due to the wide consumption of juices and carbonated beverages. Native and modified starches have diverse applications. Moreover, emerging new uses of starch and starch derivatives, such as in starch-based biodegradable plastics/starch-composite plastics and starch-based binders for metal injection molding, are an ongoing research area (Global Industry Analysts). Starch isolated from diverse cereals are named native starches. If the isolation step does not alter the organization of the starch components (amylose and amylopectin), they appear organized in concentric rings. The ordering of starch components in the granular structure is usually observed as a “Maltese cross” under a microscope with polarized light. The Maltese cross is present Modified starches 19% Starch sweeteners 55%

Native starches 26%

Figure 3.3 European consumption of starch and starch derivatives for 2015. (Data from Starch Europe, n.d. Retrieved from: http://www.aaf-eu. org; https://www.starch.eu/european-starch-industry.)

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Starches for Food Application

because of the positive birefringence that indicates a radial orientation of the principal axis of the linear chains of amylopectin that produce the crystalline areas of starch granules. The absence of the Maltese cross is due to starch disorganization, but depending on the degree of starch damage, a percentage of starch granules will present the Maltese cross. The ordering of the amylopectin linear chains can be observed by the X-ray diffraction pattern, which is different for each starch type and depends on the amylopectin structure. Cereal starches give the arbitrarily named A-type X-ray diffraction pattern, which is characterized by amylopectin short chains. In the A type, the amylopectin chains are arranged in a monoclinic lattice. In this monoclinic cell, the two double helices are formed by 12 glucopyranosyls that are packed in a parallel arrangement. In each unit cell, there are four water molecules between the helices, producing a more densely packed crystal structure. The Maltese cross and the X-ray diffraction pattern are lost during starch gelatinization (heating) and modification (chemical, physical, and enzymatic). The arrangement of the components (amylose and amylopectin) in the starch granule, observed via the Maltese cross and the X-ray diffraction pattern, is lost when the starch is heated in excess water, a mandatory step in the processing of starchy products before consumption. However, it is important to point out that the granule “ghosts” (disorganized starch granules after gelatinization, in which disorganized amylopectin is maintained) and the reorganization of linear starch chains in the continuous phase in “new” crystalline zones are important in the functionality and digestibility of starch in cooked products.

3.2.1 Isolation Process In the wet milling method, the cereal grains are immersed in water or solution (to avoid the oxidation) to soften the tissue before milling (e.g., citric acid, sodium bisulfite, etc.). The grains are steeped between 8 and 10 h; afterward, the grains and

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the steeping solution are milled to obtain a starchy solution that is sieved at different mesh sizes (50, 100, and 200 US sieve size). The residue in the meshes is washed with tap water until the water is free of apparent residues of starch. The starch solution is stored during some hours to obtain sedimentation of the starch. The supernatant (water) is removed and the sediment is centrifuged to recover the wet starch, which is finally dried in a conventional oven at 40e45
C for 24 h. A modification of the wet milling method is used as the first step in the production of flour from cereal grains. The flour is produced after milling of the grain, and it presents a water content between 12 and 15 g/100 g. Afterward, the flour is blended with water or solution and the process for starch isolation is carried out as mentioned earlier. The wet milling and tabling method was used at the laboratory scale for starch isolation from corn (Eckhoff et al., 1996); this procedure separates by density difference the protein and the starch. The method uses tables with a slight slope whereby the starch (white residue) is remains behind. Afterward, the starch is sectioned out with a spatula. Hydrocyclones are used to separate protein from starch in laboratory wet milling (Singh and Eckhoff, 1996). Starch isolation at laboratory and pilot-plant scales using wet milling showed differences, but the starch yield and the separation of other components (protein, fiber) can be comparable to those obtained at the industrial level (Singh and Eckhoff, 1996). The dry milling process involves sieving and air classification for separation of the grain components (proteins, starch, and fiber), but a lower efficiency compared with wet milling is obtained. Dry milling produces separation of the outer layers of the grain (germ and pericarp) from the starchy endosperm. The recovery of starch from the dry milling process is not reasonable even though fine grinding of the grains and air classification are used. If both milling processes are compared, wet milling produces a commercially satisfactory yield and quality of starch; however, other variables such as labor cost, residues, etc.,

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Starches for Food Application

should be considered in the wet milling process. Attempts have been made to isolate starch by combining the wet and dry milling processes. Other methods includes starch recovery from corn flour with alkaline solutions (Mistry and Eckhoff, 1992a,b) and starch separated from corn grits with sulfur dioxide (Eckhoff et al., 1993). Studies on the structural, physicochemical, functional, and digestibility characteristics of cereal starches as a preliminary step for industrial uses are widely reported. The first step is starch isolation with high purity; studies using amaranth starch (Bello-Perez et al., 1998; Choi et al., 2004; Paredes-López et al., 1989, 1994; Sing et al., 2014), maize (Juárez-García et al., 2013; Yuan et al., 1993), rice (Chavez-Murillo et al., 2012; Palma-Rodriguez et al., 2012), and wheat (Greenwell and Shofield, 1987; Lineback and Rasper, 1988; Yoo and Jane, 2002) have been reported to determine the chemical composition, amylose/amylopectin ratio, and functional and physicochemical characteristics, as well as some applications. Those studies show the importance of new varieties of cereals and pseudocereals for starch isolation and use in diverse industries. Many of the isolated starches can be used for specific applications, e.g., high-amylose maize starch is recommended as a dietary fiber source when added to low-moisture foods because it is not gelatinized completely and maintains a high resistant starch (RS) content.

3.2.2 Starch Modification Native starches do not always meet the functional characteristics for diverse industrial applications and therefore they can be modified by diverse methods. The methods to modify starch structure include chemical, physical, and enzymatic treatments, and the use of two or more methods. The products that include starch as raw material are foods, drugs, cosmetics, plastics, adhesives, paper, etc. For most of these products, modified starches are required because native starches show low shear

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resistance, thermal sensitivity, and high retrogradation (Sandhu and Singh, 2007). The different treatments to obtain a modified starch involve changes or alterations in the structure of amylose and amylopectin. Chemical modification introduces functional groups that depend on the reagents used, e.g., acetyl, carbonyl, carboxyl, phosphate, etc. In general, chemical modification is achieved with low amounts of reagents (Thomas and Atwell, 1999; Rutenberg and Solarek, 1984) that are approved by the regulatory agencies of the United States (Title 21 federal regulations code, Section 172.892) (Thomas and Atwel, 1999). The reaction is usually carried out in aqueous medium, with a solid concentration between 30% and 45% solids (by weight), pH 7e12 under stirring, and controlled temperature. The temperature in the reaction vessel should be controlled to avoid gelatinization of starch and allow the recovery of starch after water washes and separate out the unreacted reagents, salts, and other soluble reaction products before final recovery of the modified starch (Rutenberg and Solarek, 1984). The reaction is stopped by neutralizing the medium and the purified and dried starch is obtained with high efficiency (up to 70%) (Thomas and Atwell, 1999). Chemical modification of starch implies reactions in which the hydroxyl groups (OHe) of GUs participate. The impact of the chemical modification is measured by the degree of substitution (DS), a measure of the average number of OH groups in each GU that are replaced by chemical substituents. Each GU has three OHe available for reaction, so the maximum DS is 3. If the chemical group (acetate, phosphate) reacts strongly, the reaction can form polymeric substituents. Molar substitution expresses the modification level, and the units are moles of substituent groups per mole of UAG (Rutenberg and Solarek, 1984). In general, chemically modified starches that are commercially available have a DS less than 0.2. Those chemically modified starches do not cause damage to health, are considered toxicologically safe, and can be used in foods and drugs where

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safety requirements are high. Chemical modification of starch can be performed by derivatization and conversion. The conversion reduces the viscosity of the starch solution, which is desirable in some applications, for example, salad dressings and pie fillings. Starches modified by conversion can be used in products in which high concentrations (more than 6%) are necessary because of greater solubility. Crosslinking of starch is a common modification used in the industry to reduce or restrict the swelling of starch granules and give increased thermal stability and resistance to acid conditions. Starch can be physically modified using diverse methods; the physical treatments involve changes in the structure of native starches. Physical modifications involve thermal treatments, high pressure, extrusion, ultrasound, microwaves, ultraviolet light, radiation, and ohmic heating. The methods to produce physically modified starches alter their original structure (arrangement of starch components), which has an impact on their functional properties. Physically modified starches can be used in applications in the paper, textile, plastics, chemicals, and food industries, among others. Starches modified by these methods are considered safe and natural materials, preferred over starches obtained by chemical modifications (Jacobs and Delcour, 1998). Thermal treatment (autoclaving) followed by cooling is used to produce RS powder using high-amylose maize starch. Physical treatments produce changes in the starch structure due to reorganization of the starch components during cooling. Thermal treatment cycles produce depolymerization of starch components, which are reorganized during cooling; the reorganized starch structure is not recognized by digestive enzymes and this RS is part of the dietary fiber. Enzymatic treatments to modify starch structure and obtain derivative products have been proposed, including hydrolysis of starch to obtain maltodextrins and syrups. The enzymatic hydrolysis of maize starch to obtain maltodextrins uses thermostable a-amylase; the hydrolysis is achieved until it reaches an equivalent dextrose of 20, which is the chemical

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characteristic of a maltodextrin. If the enzymatic hydrolysis with a-amylase continues it is possible to obtain smaller molecules, namely, syrup solids. Production of glucose syrup needs a second enzyme in the hydrolysis vessel (amyloglucosidase) to hydrolyze the starch short chains with a-1,4 and a-1,6 linkages and produce glucose. The glucose syrup can be used to produce fructose syrup by isomerization with glucose isomerase. Structural changes to modify starch digestibility have been proposed; they include hydrolysis with b-amylase, an enzyme that hydrolyzes the second a-1,4 linkage from the nonreducing ends of linear (amylose) and branching (amylopectin) starch components, as well as transglucosidase, which participates in hydrolytic and transfer reactions to form new a-1,6 linkages (branching points). The enzymatic treatments of maize starch result in an increase in slowly digestible starch (SDS) content compared with its native counterpart. The increase in SDS was related to a high level of a-1,6 linkages after the enzymatic treatment (Ao et al., 2007). SDS was prepared using amylosucrase because this enzyme transfers glucosyl units to elongate the nonreducing ends of a-1,4 glucans using sucrose (Kim et al., 2014; Zhang et al., 2017).

3.3 PHYSICOCHEMICAL AND FUNCTIONAL PROPERTIES The physicochemical and functional characteristics of starch are important to determine and suggest applications. Properties such as gelatinization, retrogradation, rheological characteristics, pasting profile, water retention capacity, swelling, and solubility of native and modified starches are necessary to determine the end uses. The most important physicochemical properties of starch are determined under cooking or heating in the presence of water. This is because starch or starchy products are cooked or heated before consumption as food, or during their use as ingredients for food and other products, to achieve the desired

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characteristics (e.g., viscosity). In this sense, the pasting profile, using a Brabender Visco-Amylo-Graph or Rapid Visco Analyser or a starch cell, is determined in both native and modified starches to know the functionality during heating of a starch dispersion. In general, waxy starches show higher peak viscosity than their counterparts with higher amylose content, but the former present poor gel formation during the cooling step. This pattern is related to the network produced during cooling due to reassociation of the lixiviated amylose chains during the heating step and the inclusion of swollen granules (named ghosts) in which disorganized amylopectin is maintained. Moreover, if other components such as lipids, proteins, single carbohydrates, and salts are present in the formulation, they can modify the pasting profile of starch and consequently the viscosity of the paste.

3.3.1 Gelatinization Gelatinization is an irreversible physicochemical property that is unique to starch and is produced when a food formulation is in excess water. This property is important to determine the thermal processing of starch during application in foods. Gelatinization (partial or complete) is a mandatory step during processing of starchy foods (where starch is part of the food or is added as ingredient), which gives their functionality and digestibility. Starch gelatinization involves diverse changes in the granule, such as loss of birefringence, granular swelling, starch solubilization, and increase in viscosity. An old method to determine starch gelatinization was by microscopic observation; when 50% of the starch granules lost their birefringence gelatinization was said to have occurred. Differential scanning calorimetry (DSC) is used to determine the temperature and enthalpy to produce starch gelatinization. Gelatinization characteristics of starch from diverse botanical sources show high variation and it is not possible to define a pattern. It is reported that wheat starch presents lower gelatinization

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temperature than potato and cassava starches (tubers), but maize and rice starches show the highest gelatinization temperature (Waterschoot et al., 2015). In a review of the thermal properties (gelatinization) of cereal starches controversial findings can be observed. For instance, native starch isolated from different wheat cultivars showed differences in temperature and enthalpy of gelatinization (Shevkani et al., 2017); however, in our laboratory maize starch isolated from two varieties with different endosperm type presented only slight difference in temperature and enthalpy even when they were collected at 20 and 50 days after pollination (Juarez-Garcia et al., 2013). Comparison of gelatinization characteristics of wheat starches showed that waxy starch had higher temperatures of gelatinization than normal and high-amylose starch (Zhang et al., 2013; Blake et al., 2015; Li et al., 2016). However, the comparison is difficult; in our experience with the DSC test, it is difficult to obtain gelatinization characteristics of high-amylose starches with the same experimental conditions used for normal starches. This pattern can be related to the restricted swelling of the high-amylose starch granule. These controversies are more related to the method of starch isolation, sample preparation during the DSC test, and variables involved during the analysis. Any modification (chemical, physical, enzymatic, or dual) alters the gelatinization characteristics of cereal starches. Modification of starch produces changes in the gelatinization characteristics, with a decrease in the temperature and enthalpy values compared with the native counterpart. However, one type of modification known as “annealing” produces an increase in the gelatinization temperature due to the perfection of the crystalline zones in the granule. The range of temperatures of the phase transition (gelatinization) can be narrow or wide depending on the granule size distribution. The temperature and enthalpy of gelatinization are important to suggest the end use of the starch and the thermal treatment in food preparation.

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When the gelatinized starch is cooled and stored under a specific temperature (usually lower than the glass transition temperature), starch chains lixiviated during heating in excess water are organized in an ordered structure different from the original starch structure. At longer storage time (and depending on the starch source), the amylopectin maintained inside of the ghost granules is reorganized too; this phenomenon is described as starch retrogradation. The starch source plays an important role in retrogradation. For example, in starch with a high amylose content, retrogradation is high and fast; in contrast, waxy starch shows low and slow retrogradation. The rearrangement of starch components during retrogradation is observed in the texture of starchy products as bread staling and hardness of tortillas and pasta. The starch retrogradation level can be evaluated using DSC. Here, after gelatinization is carried out by heating of starch dispersion in excess water (up to 70% of dry weight starch) and assessed by DSC, the hermetically sealed pans are stored under refrigeration temperature for different times and reanalyzed in the DSC machine to determine the transition phase due to starch retrogradation. In general, the retrogradation temperature and enthalpy are lower than those obtained during starch gelatinization. This change comes about during storage, as imperfect or small crystals, which present low thermal stability and can be disorganized at lower temperatures, are produced. The enthalpy value reflects the reorganization level of the starch components during storage and is an indirect measurement of this phenomenon. Enthalpy values of gelatinized starches of normal maize, wheat, and rice stored for 7 days at 4
C were 5.8, 3.6, and 5.3 J/g, which is due to the retrogradation phenomenon (Jane et al., 1999). The enthalpy value of retrograded samples usually represents between 25% and 36% of that determined during gelatinization (Ao and Jane, 2007; Liu and Ng, 2015). The retrogradation phenomenon can be reverted when starch or starchy products are reheated, but if they are cooled in a few minutes the starch components are reorganized again.

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3.4 STARCH DIGESTIBILITY

Hydrolysis rate %

Actually, starch digestion is an important nutritional characteristic because of the health problems associated with carbohydrate consumption. It was reported that starch in foods contains a portion that digests rapidly (rapidly digestible starch, RDS), a fraction that is slowly digested (SDS), and one more that is resistant to hydrolysis by digestive enzymes (RS) (Fig. 3.4) (Englyst et al., 1992). Starch present in foods contributes between 50% and 70% of the energy in the diet and is a source of glucose, which is a substrate for brain and red blood cells for generating metabolic energy (Peery et al., 2007). However, the excessive consumption of RDS may be an element in some diet-related illnesses such as obesity, diabetes, and hypertension. SDS, which is slowly hydrolyzed in the small intestine, has been associated with health benefits due to a slower release of glucose into the blood, resulting in reduced postprandial glycemic and insulin responses. Undigested starch that reaches the colon is a prebiotic, a substrate for microbiota present in the colon. It is well known that changes in diet may help prevent the

RDS

20 min

SDS

RS

20-120 min Time

Figure 3.4 Position of absorption in the gut and hydrolysis rate of starch fractions. RDS, rapidly digestible starch; RS, resistant starch; SDS, slowly digestible starch. (Based on Englyst, H.N., Kingman, S.M., Cummings, J.H., 1992. Classification and measurement of nutritionally important starch fractions. European Journal of Clinical Nutrition. 46, S33eS50.)

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development of diet-related diseases; thus consumer interest in “more natural foods” is increasing. As a result, it is a current need and important objective in the food industry not only to understand how processing affects starch digestibility, but also to develop heat-stable SDS/RS structures that, when added to food formulations, undergo no changes in their digestion characteristics. Starch application in the food industry is defined by considering its availability and its physicochemical characteristics, which vary depending on the source. Maize is the main botanical source for starch isolation, representing around 80% of the world starch market. Maize starch is an ingredient used in food formulations because it imparts functional properties such as thickener, stabilizer, colloidal gelling, and water retention, and it is used as an adhesive (Zhu and Wang, 2013). Native starch is a texture stabilizer and regulator in foods (Considine, 2012), but it has drawbacks such as low shear resistance, low thermal resistance, high thermal decomposition, and high tendency to retrogradation; thus its use is restricted in diverse food applications (Betancur and Chel, 1997). Starch modification alters the physical and chemical characteristics of the native starch to improve its functional characteristics (Miladinov and Hanna, 2000); starch modification has been used to tailor starch to specific applications. Cereal starch modification has been investigated with the objective to change its digestibility, maintaining high SDS and RS content even after cooking, so it can be used in the formulation of diverse foods (Table 3.1) (Chen et al., 2015; Chung et al., 2009; Jiang et al., 2014; Shin et al., 2004; Simsek et al., 2015; Van Hung et al., 2016; Wang et al., 2016). Considering that resistance to enzymatic hydrolysis and slow digestion characteristics are related to the arrangement of starch components determined by the X-ray diffraction pattern, the chain length distribution, and the branching points of amylopectin (Ao et al., 2007), it is important to study the structural

Table 3.1 Treatments used to produce slowly digestible or resistant starch fractions Starch fraction digestion Native Starch source

Modified

Treatment

SDS (%)

RS (%)

SDS (%)

RS (%)

References

ANN

3.7

6.3

10.7

19.5

Van Hung et al. (2016)

ANN ANN HMT HMT

14 12.8 6.2 7.4

6.5 10.2 2.1 6.6

19 16.5 18.9 18.8

22.6 26.9 11.7 29.5

HMT ANN HMT HMT

4.9 47

2.3 4 24.2

14.3 3 3.5 26.0

Chen et al. (2015) Liu et al. (2015)

21.9

1.1 50 57.5 32.89

PULs PULs PULs þ crystallization 4-a-GTs

15.4 13.2

5.9 11.4

30.2 27.6 31.4

13.1 10.9 16.3

Cheng et al. (2017) Zeng et al. (2015)

Physical

Oat

Wang et al. (2016)

Ovando-Martínez et al. (2013)

Enzymatic

Rice Waxy rice Corn

Jiang et al. (2014)

89

Continued

Cereal Starch Production for Food Applications

High-amylose rice Rice Waxy rice Maize High-amylose maize Wheat Buckwheat

Starch source

Treatment

Modified

SDS (%)

RS (%)

SDS (%)

RS (%)

15.4 16.3 13.0 0.01

5.4 2.4 6.1 7.3

12.2

0

20.0 14.1 19.1 0.05 0.02 19.9 12.9 20.9 20.6 22.7

9.4 9.0 9.3 19.5 7 12.9 24.2 13.9 25.6 40.7

References

Chemical

Corn Rice Wheat Corn Waxy corn

ESTER ESTER ESTER HP CL CL (without salt) CL (without salt)eAC CL (without salt)eHP HPeCL HPeESTER

Simsek et al. (2015) Simsek et al. (2015) Chung et al. (2009) Han and BeMiller (2007)

4-a-GTs, 4-a-glucanotransferase; AC, acetylated starch; ANN, annealing; CL, crosslinked starch; ESTER, esterified starch; HMT, heatemoisture treatment; HP, hydroxypropylated starch; PULs, pullulanase; RS, resistant starch; SDS, slowly digestible starch.

Starches for Food Application

Native

90

Table 3.1 Treatments used to produce slowly digestible or resistant starch fractionsdcont'd Starch fraction digestion

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91

changes that occur during starch modification to understand their effects on starch digestibility and the altered functional properties. Raw cereal starches show high SDS and RS content, with higher SDS than RS (Zhang et al., 2006a). However, when those starches are cooked, SDS and RS decrease with a concomitant increase in RDS (Zhang et al., 2006b), due to the disruption of the double helices. To avoid the SDS/RS loss, diverse studies have used hydrothermal treatments and enzymatic or chemical modifications that induce changes in the starch crystallinity and reinforce intramolecular bonds, thus affecting the starch hydrolysis pattern (Table 3.1) (Chung et al., 2009; Ovando-Martínez et al., 2013; Wang et al., 2016). Miao et al. (2009) used pullulanase on gelatinized waxy maize starch to produce SDS and found that high enzyme concentration and less debranching time increased the amount of SDS, whereas longer times accelerated the production of RS. The change in the enzyme concentration modified the number of imperfect packing helices in crystallites, hence altering the ratio of amorphous and crystalline zones associated with SDS. The amylose-to-amylopectin ratio is another main factor affecting starch digestibility. In different wheat types and cultivars waxy starches are generally a source of RDS; meanwhile, high-amylose starches have a higher proportion of SDS and RS (Salman et al., 2009; Zhou et al., 2014). The high susceptibility of waxy starch to enzymatic hydrolysis may be attributed to more surface area per molecule of amylopectin (Naguleswaran et al., 2014). On the other hand, high-amylose starches are of interest to the food industry (Richardson et al., 2000); these give a high gelling strength that is desirable in sweets. Also, they have film-forming properties, and thus are used as a coating on fried products, making them crispy and reducing their fat uptake upon cooking (Bird et al., 2000). Moreover, while regular corn starch is hydrolyzed in the small intestine, high-amylose starches such as Hi-Maize 260, Hylon VII, and Novelose 330 contain a high percentage of RS, which

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has nutritional benefits (Richardson et al., 2000). Clinical studies have demonstrated that RS is not digested in the small intestine and it is moved to the bowel, where it is fermented by probiotic bacteria with the production of short-chain fatty acids (SCFAs) (Cummings and Englyst, 1991). Some health benefits have been associated with SCFAs, such as reduction of the luminal pH, which inhibits pathogenic microorganisms and increases the absorption of nutrients (Macfarlane and Macfarlane, 1993). Furthermore, in the intestinal absorption of SCFAs, mainly butyrate is metabolized by the large intestinal epithelial cells (colonocytes), with the inhibition of the malignant transformation of colonocytes, as it serves as the main energy source for these cells (Clarke et al., 2011). Such characteristics help to determine the main applications of these high-amylose RSs, which include fiber-fortified foods such as breakfast cereals, cakes, and cookies, providing a better appearance, texture, and mouthfeel than traditional fiber sources (Table 3.2). For example, Novelose 330, a nongranular, retrograded starch (RS3) from corn starch with an RS content up to 30%, is recommended especially for extruded food products; however, it has been used for production of fried battered foodstuffs because of its resistance to frying conditions (185
C) (Sanz et al., 2008).

3.5 FOOD APPLICATIONS Cereal starches are widely utilized in the industry, including in food formulations. As was mentioned, native starches do not meet the physicochemical and functional features required by foods, so they are modified. In this sense, modified starches are used for food purposes. Maize, wheat, and rice starches are commercially available; they are used to modify the texture and appearance of foods. Starch modifies the adhesiveness, thickening, glazing, emulsion stability, binding, clouding, foam stability, moisture retention, dusting, expansion, crisping, and

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Table 3.2 Foods enriched with resistant starch ingredients Food product RS used Observations References

Muffins

Hi-Maize 1043

Biscuits

Hi-Maize 260

Cake

Corn RS

Amounts of RS under 10% by weight of the total formulation hardly influenced the muffin height or the number and area of gas cells in the crumb, which are commonly taken as quality indices. Further increases in the RS content decreased these parameters significantly Replacing part of the flour with the RS gave crumblier, tenderer, less hard textures and shapes that spread less; consumer acceptance of the biscuits was good Increasing the level of RS caused an increase in cake density but a decrease in volume

Baixauli et al. (2008)

Laguna et al. (2011)

Majzoobi et al. (2014)

RS, resistant starch.

gelling, therefore is widely used in foods (Table 3.3). Maize starch is widely used because of its pasting properties, which are different depending on the amylose content. Waxy maize starch (1% amylose) produces brightness and a translucent paste with weak structure, while high-amylose starch (50%) is an opaque and stiff paste that produces hard gels used in gum candies. Normal maize starch (30% amylose) is used to produce sweeteners (glucose, corn syrup) and fat substitutes (maltodextrins, maltooligosaccharides, isomaltooligosaccharides) (Nakakuki, 1989).

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Table 3.3 Functionality and uses of cereal starches Starch Functions Food applications

Maize

Thickener, binder, filling, stabilizer, gelling, and food additive

Wheat Rice

Gas by fermentation and rigid network binder, thickener, adhesive agent Binder, fat mimetic, freezee thaw stability, whiteness, dusting, crispness agent, and thickener

Barley Oat

Gelling and thickness agent Fat replacer and emulsifier

Sweetener products, thick sauce, smooth food texture, glutinousness, formed meat, confectionary fillings, candies and batters, jamfilled waffles, emulsifiers, and encapsulators of antioxidant compounds Bakery products, batters, ice cream, soups, gravies, dressings, and yogurts Confectionery, pastries, puddings, custards, smooth gravies, sauces, soups, snacks, ice cream, baby foods, and freeze ethawed cake Desserts Frozen desserts, ice creams, instant breakfast drinks, dressings, gravies, and sauces

Maize starch is modified to improve functionality; waxy maize starch is hydrolyzed with acid or enzymes to produce nanocrystals that are used to stabilize Pickering emulsions; also, it can be modified with n-octenyl succinate acid to improve its hydrophobic character and water holding capacity. Such starches are used as bread improvers because they can substitute for the fat, providing a soft texture (Hadnadev et al., 2014). Waxy maize starch is pregelatinized by physical treatments (extrusion or drum-dryer) to use in jelly confectionery (Lagache et al., 2014).

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Wheat starch is used for moisture control, thickening, and adhesiveness in batters, ice creams, soups, gravies, and dressings; also, it is added to yogurt to provide thickening and gelling characteristics; in sausages and comminuted meats it is used to improve water-binding properties (Shevkani et al., 2017). Wheat starch is used to produce a glucose syrup and sweeteners in the beverage and confectionery industries (Cornell, 2004). Rice starch has diverse applications because it can be obtained with a wide range of amylose:amylopectin ratios, producing pastes with different texture characteristics. Rice starch is a gluten-free ingredient; therefore, is widely used in this kind of product. Rice starch presents excellent mouthfeel, is a substitute for fat, and shows freezeethawing stability with low syneresis, producing a spongy structure with a slow change in the texture of gels (Mitchell, 2009); in this sense, it is used in frozen products such as freezeethawed cakes ( Jongsutjarittam and Charoenrein, 2013). Barley starch is used as a gelling and thickening agent because after heating at 96
C for several minutes the viscosity is not modified. The internal lipids in oat starch produce amyloseelipid complexes that retard its retrogradation and solubility; oat starch is used in cheese making as a fat substitute (Zhu, 2016).

3.6 FINAL REMARKS Starch is isolated from cereals such as maize, wheat, rice, barley, and oat, and added as a raw material in products such as salad dressings, meat products, drugs, films, pie fillings, etc. More applications of cereal starches are found when they are modified, that is, as chemically treated and pregelatinized starches. The extensive use of cereal starches in foods is due to the functionality they impart to the products and because they can substitute for another kind of hydrocolloids. The search for

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nonconventional cereal starch sources has increased in past years with the aim to diversify the use of agricultural resources, exploit the underused botanical sources, and find new or improved applications of the nonconventional starches. The modification of starch structure from biosynthesis to producing specific functionalities is another topic for research.

REFERENCES Angellier, H., Choisnard, L., Molina-Boisseau, S., Ozil, P., Dufresne, A., 2004. Optimization of the preparation of aqueous suspensions of waxy maize starch nanocrystals using a response surface. Biomacromolecules 15, 1545e1551. Ao, Z., Jane, J.-L., 2007. Characterization and modelling of the A- and B-granule starches of wheat, triticale, and barley. Carbohydrate Polymers 67, 46e55. Ao, Z., Simsek, S., Zhang, G., Venkatachalam, M., Reuhs, B.L., Hamaker, B.R., 2007. Starch with a slow digestion property produced by altering its chain length, branch density, and crystalline structure. Journal of Agricultural and Food Chemistry 55, 4540e4547. Baixauli, R., Sanz, T., Salvador, A., Fiszman, S.M., 2008. Muffins with resistant starch: baking performance in relation to the rheological properties of the batter. Journal of Cereal Science 47, 502e509. Baldwin, P., 1995. Studies on the Surface Chemistry, Minor Component Composition and Structure of Granular Starches. The University of Nottingham, UK. Ph.D. thesis. Bello-Pérez, L.A., Rodríguez-Ambriz, S.L., Lozano-Grande, M.A., 2017. Molecular characterization of starches by AF4-MALS-RI: an alternative. Journal of Cereal Science 75, 132e134. Bello-Pérez, L.A., Pano de Léon, Y., Agama-Acevedo, E., ParedesLópez, O., 1998. Isolation and partial characterization of amaranth and banana starches. Starch Starke 50, 409e413. Bertoft, E., Annor, G.A., Shen, X., Rumpagaporn, P., Seetharaman, K., Hamaker, B.R., 2016. Small differences in amylopectin fine structure may explain large functional differences of starch. Carbohydrate Polymers 140, 113e121. Betancur, A.D., Chel, G.L., 1997. Acid hydrolysis and characterization of Canavalia ensiformis starch. Journal of Agricultural and Food Chemistry 45, 4237e4241. Bird, A.R., Brown, I.L., Topping, D.L., 2000. Starches, resistant starches, the gut microflora and human health. Current Issues in Intestinal Microbiology 1, 25e37.

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Blake, L.H., Jenner, C.F., Barber, A.R., Gibson, R.A., O’neill, B.K., Nguyen, Q.D., 2015. Effect of waxy flour blends on dough rheology and bread quality. International Journal of Food Science and Technology 50, 926e933. Chavez-Murillo, C.E., Mendez-Montealvo, G., Wang, Y.-J., BelloPérez, L.A., 2012. Starch of diverse Mexican rice cultivars: physicochemical, structural, and nutritional features. Starch Starke 64, 745e756. Chen, L., Tian, Y., Zhang, Z., Tong, Q., Sun, B., Rashed, M.M., Jin, Z., 2017. Effect of pullulan on the digestible, crystalline and morphological characteristics of rice starch. Food Hydrocolloids 63, 383e390. Chen, X., He, X., Fu, X., Huang, Q., 2015. In vitro digestion and physicochemical properties of wheat starch/flour modified by heatmoisture treatment. Journal of Cereal Science 63, 109e115. Choi, H., Kim, W., Shin, M., 2004. Properties of Korean amaranth starch compared to waxy millet and waxy sorghum starches. Starch Starke 56, 469e477. Chung, H.J., Hoover, R., Liu, Q., 2009. The impact of single and dual hydrothermal modifications on the molecular structure and physicochemical properties of normal corn starch. International Journal of Biological Macromolecules 44, 203e210. Clarke, J.M., Topping, D.L., Christophersen, C.T., Bird, A.R., Lange, K., Saunders, I., Cobiac, L., 2011. Butyrate esterified to starch is released in the human gastrointestinal tract. American Journal of Clinical Nutrition 94, 1276e1283. Considine, D.M., 2012. Foods and Food Production Encyclopedia. Springer Science & Business Media. Cornell, H., 2004. Starch in Food: Structure, Functional and Applications, first ed. CRC Press, New York (Chapter 7). Cummings, J.H., Englyst, H.N., 1991. Measurement of starch fermentation in the human large intestine. Canadian Journal of Physiology and Pharmacology 69, 121e129. Dufresne, A., 2014. Crystalline starch based nanoparticles. Current Opinion in Colloid and Interface Science 19, 397e408. Bioactivity and Biotechnology. Eckhoff, S.R., Jayasena, W.V., Spillman, C.K., 1993. Wet milling of maize grits. Cereal Chemistry 70, 257e259. Eckhoff, S.R., Singh, S.K., Zehr, B.E., Raush, K.D., Fox, E.J., Mistry, A.K., 1996. A 100-g laboratory corn wet milling procedure. Cereal Chemistry 73, 54e57. Englyst, H.N., Kingman, S.M., Cummings, J.H., 1992. Classification and measurement of nutritionally important starch fractions. European Journal of Clinical Nutrition 46, S33eS50.

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Greenwell, P., Schofield, J.D., 1987. Wheat starch granule protein and their technological importance. Cereal Foods World 32, 380e385. Hadnadev, T.D., Dokic, L., Pojic, M., Hadnadev, M., Torbica, A., Rakita, S., 2014. Rheological properties of dough and quality of bread supplemented with emulsifying polysaccharides. Hemljska Industrlja 68, 99e106. Han, J.A., BeMiller, J.N., 2007. Preparation and physical characteristics of slowly digesting modified food starches. Carbohydrate Polymers 67, 366e374. Hasjim, J., Lee, O.-K., Hendrich, S., Setiawan, S., Ai, Y., Jane, J.-L., 2010. Characterization of a Novel Resistant-starch and its effects of post prandial plasma-glucose and inulin responses. Cereal Chemistry 87, 257e262. Huber, K.C., BeMiller, J.N., 2000. Channels of maize and sorghum starch granules. Carbohydrate Polymers 41, 269e276. Imberty, A., Chanzy, H., Pérez, S., Buleon, A., Tran, V., 1987. New Three-dimensional structure for A-type starch. Macromolecules 20, 2634e2636. Jacobs, H., Delcour, J.A., 1998. Hydrothermal modifications of granular starch, with retention of the granular structure: a review. Journal of Agricultural and Food Chemistry 46, 2895e2905. Jane, J.L., 2007. Structure of starch granules. Japanese Journal of Applied Physics 54, 31e36. Jane, J., Chen, Y.Y., Lee, L.F., McPherson, A.E., Wong, K.S., Radosavljevic, M., Kasemsuwan, T., 1999. Effects of amylopectin branch chain length and amylose content on the gelatinization and pasting properties of starch. Cereal Chemistry 76, 629e637. Jiang, H., Miao, M., Ye, F., Jiang, B., Zhang, T., 2014. Enzymatic modification of corn starch with 4-a-glucanotransferase results in increasing slow digestible and resistant starch. International Journal of Biological Macromolecules 65, 208e214. Jongsutjarittam, N., Charoenrein, S., 2013. Influence of waxy rice flour substitution for wheat flour on characteristics of batter and freeze-thawed cake. Carbohydrate Polymers 97, 306e314. Juarez- Garcia, E., Agama-Acevedo, E., Gómez-Montiel, N.O., PandoRobles, V., Bello-Pérez, L.A., 2013. Proteomic analysis of the enzymes involved in the starch biosynthesis of maize with different endosperm tyoe and characterization of the starch. Journal of the Science of Food and Agriculture 93, 2660e2668. Kim, B.K., Kim, H.I., Moon, T.W., Choi, S.J., 2014. Branch chain elongation by amylosucrase: production of waxy corn starch with a slow digestion property. Food Chemistry 152, 113e120.

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Lagache, S., Brendel, R., Guerard, D., 2014. Jelly Confectionery e.g. Soft Candy or Chewing Gum, Comprises a Gelling Agent, Pregelatinized Waxy Starch, Soluble Vegetable Fiber, and Another Ingredient Consisting of Nutriose, Sorbitol or Glycerine. Patent FR2997828. Laguna, L., Salvador, A., Sanz, T., Fiszman, S.M., 2011. Performance of a resistant starch rich ingredient in the baking and eating quality of short-dough biscuits. Food Science and Technology 44, 737e746. Li, W., Wu, G., Lu, Q., Jiang, H., Zheng, J., Ouyang, S., Zhag, G., 2016. Effects of removal of surface proteins on physicochemical and structural properties of A- and B-starch isolated from normal and waxy wheat. Journa of Food Science and Technology 53, 2673e2685. Lineback, D.R., Rasper, V.F., 1988. Wheat, Chemistry and Technology, Third ed. Minnesota (Chapter 9). Liu, H., Guo, X., Li, W., Wang, X., Peng, Q., Wang, M., 2015. Changes in physicochemical properties and in vitro digestibility of common buckwheat starch by heat-moisture treatment and annealing. Carbohydrate Polymers 132, 237e244. Liu, Y., Ng, P.K., 2015. Isolation and characterization of wheat bran starch and endosperm starch of selected soft wheats grown in Michigan and comparison of their physicochemical properties. Food Chemistry 176, 137e144. Macfarlane, G.T., Macfarlane, S., 1993. Factors affecting fermentation reactions in the large bowel. Proceedings of the Nutrition Society 52, 367e373. Majzoobi, M., Hedayati, S., Habibi, M., Ghiasi, F., Farahnaky, A., 2014. Effects of corn resistant starch on the physicochemical properties of cake. Journal of Agricultural Science and Technology 16, 569e576. Maningat, C.C., Seib, P.A., Bassi, S.D., Woo, K.S., Lasater, G.D., 2009. Starch: Chemistry and Technology, third ed. Elsevier, New York (Chapter 10). Miao, M., Jiang, B., Zhang, T., 2009. Effect of pullulanase debranching and recrystallization on structure and digestibility of waxy maize starch. Carbohydrate Polymers 76, 214e221. Miladinov, V.D., Hanna, M.A., 2000. Starch esterification by reactive extrusion. Industrial Crops and Products 11, 51e57. Mistry, A.H., Eckhoff, S.R., 1992a. Alkali debranning of corn to obtain corn bran. Cereal Chemistry 69, 202e205. Mistry, A.H., Eckhoff, S.R., 1992b. Characteristics of alkali-extracted starch obtained from corn flour. Cereal Chemistry 69, 296e303. Mitchell, C.R., 2009. Starch Chemistry and Technology, third ed. Academic Press, Unites States of America (Chapter 13). Naguleswaran, S., Vasanthan, T., Hoover, R., Bressler, D., 2014. Amylolysis of amylopectin and amylose isolated from wheat, triticale, corn and barley starches. Food Hydrocolloids 35, 686e693.

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Nakakuki, T., 1989. (Japan Patent JP 8916599 A2). Ovando-Martínez, M., Whitney, K., Reuhs, B.L., Doehlert, D.C., Simsek, S., 2013. Effect of hydrothermal treatment on physicochemical and digestibility properties of oat starch. Food Research International 52, 17e25. Palma-Rodríguez, H.M., Agama-Acevedo, E., Méndez-Montealvo, G., González-Soto, R.A., Vernon-Carter, J., Bello-Pérez, L.A., 2012. Effect of acid treatment on the physicochemical and structural characteristics of starches form different botanicals sources. Starch Starke 64, 115e125. Paredes-López, O., Schevenin, M.L., Hernández-López, D., CárabezTrejo, A., 1989. Amaranth starch-isolation and partial characterization. Starch Starke 41, 205e207. Paredes-López, O., Bello-Pérez, L.A., López, M.G., 1994. Amylopectin structural, gelatinization and retrogradation studies. Food Chemistry 50, 411e417. Pérez, S., Bertoft, E., 2010. The molecular structures of starch components and their contribution to the architecture of starch granules: a comprehensive review. Starch Starke 62, 389e420. Perry, G.H., Dominy, N.J., Claw, K.G., Lee, A.S., Fiegler, H., Redon, R., Carter, N.P., 2007. Diet and the evolution of human amylase gene copy number variation. Nature Genetics 39, 1256e1260. Richardson, P.H., Jeffcoat, R., Shi, Y.C., 2000. High-amylose starches: from biosynthesis to their use as food ingredients. MRS Bulletin 25, 20e24. Rutenberg, M.W., Solarek, D., 1984. Starch derivatives: production and uses. Starch Chemistry and Technology 1, 312e388. Salman, H., Blazek, J., Lopez-Rubio, A., Gilbert, E.P., Hanley, T., Copeland, L., 2009. Structureefunction relationships in A and B granules from wheat starches of similar amylose content. Carbohydrate Polymers 75, 420e427. Sandhu, K.S., Singh, N., 2007. Some properties of corn starches II: physicochemical, gelatinization, retrogradation, pasting and gel textural properties. Food Chemistry 101, 1499e1507. Sanz, T., Salvador, A., Fiszman, S.M., 2008. Resistant starch (RS) in battered fried products: functionality and high-fibre benefit. Food Hydrocolloid 22, 543e549. Seib, P.A., 1994. Wheat starch: isolation, structure and properties. Oyo Toshitsu Kagaku 41, 49e69. Shevkani, K., Sing, N., Bajaj, R., Kaur, A., 2017. Wheat starch production, structure, functionality and application- a review. International Journal of Food Science and Technology 52, 38e58. Shin, S.I., Choi, H.J., Chung, K.M., Hamaker, B.R., Park, K.H., Moon, T.W., 2004. Slowly digestible starch from debranched waxy

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sorghum starch: preparation and properties. Cereal Chemistry 81, 404e408. Simsek, S., Ovando-Martinez, M., Marefati, A., Sjӧӧ, M., Rayner, M., 2015. Chemical composition, digestibility and emulsification properties of octenyl succinic esters of various starches. Food Research International 75, 41e49. Singh, H., Eckhoff, S.R., 1996. Wet milling of corn- A review of laboratoryscale and pilot plant-scale procedures. Cereal Chemistry 73, 659e667. Singh, N., Kaur, S., Kaur, A., Isono, N., Ichihashi, Y., Noda, T., Rana, J.C., 2014. Structural, thermal, and rheological properties of Amaranthus hypochondriacus and Amaranthus caudatus starches. Starch Starke 66, 457e467. Starch Europe, n.d. Retrieved from: http://www.aaf-eu.org; https:// www.starch.eu/european-starch-industry. Tang, H., Ando, H., Watanaba, K., Takeda, Y., Mitsunaga, T., 2001. Physicochemical properties and structure of large, mediun and small granule starches in fractions of normal barley endosperm. Carbohydrate Research 330, 241e248. Thomas, D.J., Atwell, W.A., 1999. Starches. American Association of Cereal Chemists Inc., St. Paul, MN. Van Hung, P., Chau, H.T., Phi, N.T.L., 2016. In vitro digestibility and in vivo glucose response of native and physically modified rice starches varying amylose contents. Food Chemistry 191, 74e80. Wang, H., Zhang, B., Chen, L., Li, X., 2016. Understanding the structure and digestibility of heat-moisture treated starch. International Journal of Biological Macromolecules 88, 1e8. Wang, S., Copeland, L., 2013. Molecular disassembly of starch granules during gelatinization and its effect on starch digestibility: a review. Food and Function 4, 1564e1580. Waterschoot, J., Gomand, S.V., Fierens, E., Delcour, J.A., 2015. Production, structure, physicochemical and functional properties of maize, cassava, wheat, potato and rice starches. Starch Starke 67, 14e29. Yoo, S.H., Jane, L., 2002. Structural and physical characteristics of waxy and other wheat starches. Carbohydrate Polymers 49, 297e305. Yuan, R.C., Thompson, D.B., Boyer, C.D., 1993. Fine structure of amylopectin in relation gelatinization and retrogradatión behavior of maize starch from three wx containing genotypes in two inbred lines. Cereal Chemistry 70, 81e89. Zeng, F., Chen, F., Kong, F., Gao, Q., Aadil, R.M., Yu, S., 2015. Structure and digestibility of debranched and repeatedly crystallized waxy rice starch. Food Chem 187, 348e353. Zhang, B., Li, X., Liu, J., Xie, F., Chen, L., 2013. Supramolecular structure of A-and B-type granules of wheat starch. Food Hydrocolloids 31, 68e73.

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Zhang, G., Ao, Z., Hamaker, B.R., 2006a. Slow digestion property of native cereal starches. Biomacromolecules 7, 3252e3258. Zhang, G., Venkatachalam, M., Hamaker, B.R., 2006b. Structural basis for the slow digestion property of native cereal starches. Biomacromolecules 7, 3259e3266. Zhang, H., Zhou, X., He, J., Wang, T., Luo, X., Wang, L., Chen, Z., 2017. Impact of amylosucrase modification on the structural and physicochemical properties of native and acid-thinned waxy corn starch. Food Chemistry 220, 413e419. Zhou, Z., Zhang, Y., Chen, X., Zhang, M., Wang, Z., 2014. Multi-scale structural and digestion properties of wheat starches with different amylose contents. International Journal of Food Science 49, 2619e2627. Zhu, F., Wang, Y.J., 2013. Characterization of modified high-amylose maize starch-a-naphthol complexes and their influence on rheological properties of wheat starch. Food Chemistry 138, 256e262. Zhu, F., 2016. Buckwheat starch: structures, properties, and applications. Trends in Food Science and Technology 49, 121e135.

FURTHER READING Agrana research & innovation center, n.d. Retrieved from: http://www. zuckerforschung.at/. Global Industry Analysts. The global starch market, n.d. Retrieved from: http://www.strategyr.com/MarketResearch/Starch_Market_Trends.asp.

CHAPTER 4

Starch Extracted From Corms, Roots, Rhizomes, and Tubers for Food Application Olivier François Vilpoux, Vitor Hugo Brito, Marney Pascoli Cereda

Center of Technology and Agribusiness Analysis - Catholic University (CeTeAgro/UCDB), Campo Grande, Brazil

Contents 4.1 Introduction 4.2 Commercial Starch Worldwide 4.3 Crops that Store Starch in Underground Organs 4.3.1 Plants Capable of Storing Starch in Underground Structures 4.3.2 What Differentiates the Starches Extracted From Underground Organs? 4.3.2.1 White Color Is a Distinctive Feature of Starches 4.3.2.2 The Crystallinity Pattern Is Also a Distinctive Feature of Starches 4.3.2.3 Shape and Size of Starch Granules as Indicative 4.3.2.4 Influence of Plant Genetics on the Starch Characteristics 4.3.2.5 Organic Phosphate Content in the Starch Structure 4.3.2.6 Technological Properties and Relations to Industrial Applications 4.3.2.7 Interactions of Starch with Other Ingredients Used in Food

4.3.3 Issues with Commercial-Scale Production 4.3.3.1 The Arrowroot Case (Maranta arundinacea L.)

104 106 114 115 120 120 122 122 123 124 124 129 131 131 132 134

4.3.4 Issues with Commercial-Scale Starch Extraction 4.4 How to Find Interesting Starches With Potential Uses 4.5 The Starches With the Most Potential: Their Advantages and Disadvantages 4.6 Final Considerations References

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© 2019 Elsevier Inc. All rights reserved.

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4.1 INTRODUCTION Starch is a caloric food ingredient, used throughout the world to provide proper characteristics to food products. As an ingredient, it influences the organoleptic characteristics, aiding or hindering chewing by introducing crispness or softness. The release of sugar as assessed by the glycemic index is influenced by the high or low enzymatic digestibility (Lunn and Buttriss, 2007; Fuentes-Zaragoza et al., 2010; Wang et al., 2015). Despite the variety of competitors of lower or no calorific value (gums and mucilage), its consumption is high, due to its availability, low cost, good storage, and ease of use. The starch added to food may be visible to the consumer because of its clear utilization or may be practically invisible when it is used in minimal amounts as an additive. In any case, according to food law requirements, the presence of starch in any food product must be clearly identified on labels and formulations. Two sorts of starch are available on the market, the native type and the modified type. Native starches retain the characteristics they already possess in the plants they are extracted from, while modifications (physical, chemical, enzymatic, or their combinations) change the characteristics of native starches in a way to better meet technological requirements. Native starch is available in abundance in the environment, and it is estimated that plants produce at least about 2.825 million tonnes of starch through photosynthesis annually (Burrell, 2003), an amount smaller only than that of cellulose. Starch is the main reserve of energy of plants, being deposited in the form of water-insoluble granules in a storage organ. Native starches also present variations in shape, size, and functional properties (Weber et al., 2009; Eliasson, 2004). As food formulations are quite variable (sweet, salty, dried; with sauces, condiments, etc.), the desirable characteristics conferred by the starch on the food can vary greatly.

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Starch is the main component of several grains, representing 70%e80% of their composition, in addition to being found in roots and tubers (Zeoula et al., 1999). Starches extracted from underground raw materials are more commonly found in tropical regions and are less studied than the starches obtained from cereal grains. Native starches have as their advantage a lower production cost, since when there is a need for modification, another process is added to those of extraction and drying, resulting in a price increase. In addition, chemical reagents are a risk to the operator, to the equipment, to the environment, and to the consumer, in addition to the instability of the final product, which may happen when there are residues of chemical reactions during storage. Native starches have been gaining attention for years because of their unique quality characteristics linked to their botanical source and mainly because of their reliability in the opinion of consumers. This global interest on the part of academic researchers and even of companies has yielded a large number of publications since the 1990s. Most of these publications are from tropical regions, highlighting some botanical sources in India, China, Thailand, Indonesia, and South America, including Brazil. In this search for new starch sources, several research centers, universities, and even companies have been involved (FAO, 1994; Moorthy et al., 1996; Hermann, 1997; Pérez et al., 2006; McPherson and Jane, 1999; Moorthy, 2002; Leonel and Cereda, 2002; Cereda, 2002; Zhang et al., 2008; Nuwamanya et al., 2011). The emphasis on the search for native starches for application in food products highlights the fact that native starches do not undergo chemical modifications to meet the needs of heat processing or storage in refrigerated or frozen environments, although some of these special starches naturally present chemical modifications. In 2018, the appeal of native starches with modified starch properties continues. On the website of

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the American company Ingredion (Clean label - Ingredion, 2018) the company announces 20 years of clean label innovation with the brand line NOVATION of functional native starches. The company defines clean labels as products based on customer insights, such as free from additives (remove or replace food additives), featuring a simple ingredient listing (choose recognizable ingredients that do not seem chemical or artificial), and minimally processed (process foods using traditional techniques that are understood by consumers and not perceived as being artificial). The products of the line NOVATION from the point of view of the use of starches constitute, basically, a physical mixture of native starches as food ingredients. Despite this interest, there were few actual results of the adoption of new botanical starch sources. Although starches with differing properties have been found, little is known about why these starches are different, even considering the advances in the knowledge of fine starch chemistry. Some of the hypotheses point to their pasting properties, granule size or percentages of different granule sizes, or the presence of phosphorus, but each of these characteristics explains only part of the results. This chapter discusses the potentiality of alternative sources of starch, with a focus on those extracted from underground raw materials, and some strategies for finding and evaluating them. However, first, it is important to know what the starch market presents on a global level.

4.2 COMMERCIAL STARCH WORLDWIDE It is possible to divide the starch market into two, the commodity market, with standardized products available in large quantities all year round and worldwide, and the differentiated market, with special starches having characteristics valorized in certain uses, which allows their commercialization at higher prices. Native starches can be found in these two markets, where the original

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starch properties are preserved; the modified starches are also found in both markets, presenting properties that are modified by the use of heat, enzymes, and several chemical products. Often the literature highlights a third type of starch, the sweeteners, where the starch undergoes enzymatic or chemical modifications to obtain a sugar, which can be glucose, maltose, or fructose. Production of starch in the commodity market has grown significantly in recent years, associated with the increase in the world population and the average income per capita. The world production increased from 60 million tonnes in 2007 (Maningat et al., 2009) to 75 million tonnes in 2012 (Waterschoot et al., 2015) and 90 million tonnes in 2016 (Teagasc, 2017). Despite this growth, world starch production is based mainly on four raw materials: corn (Zea mays L.), which accounts for more than 75% of world production (Teagasc, 2017; Waterschoot et al., 2015), cassava (Manihot esculenta Crantz), (Triticum aestivum L.), and potato (Solanum tuberosum L.) (Table 4.1). According to FAO (2017a), China has passed the United States as the largest corn user for starch production. Data from 2017 point to the use of 50 million tonnes of corn for starch production in China against 29 million tonnes in the United States. In 2016, the United States used 6 million tonnes of corn for native and modified starch production, excluding the production Table 4.1 World production of starch as a function of the raw material used Based on Teagasc (2017) Waterschoot et al. (2015) and FAO (2017a) Year

2015

2016

Corn Wheat Potato Cassava

64.6 6.0 3.4 10.2

67.5e72.0 6.3e8.1 7.2e9.0 6.3e8.1

Data are provided in units of million tonnes.

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of sugars, which represents 1.7% of the domestic production. About 8 million tonnes of corn was used for sweetener production, which represented 2.2% of the national corn production, and 12 million tonnes for the production of highfructose corn syrup (HFCS), representing 3.3% of national corn production (National Corn Growers Association, 2017). The North American ethanol market used 107 million tonnes of corn in 2016, or 28.9% of the domestic corn production, which is not accounted for in the starch market because it is processed directly from the grain. The use of starch to produce HFCS is one of the differences between the North American market and the European market, which is focused essentially on the markets of native starches, modified starches, and sweeteners. About 19% of the 9.3 million tonnes of starch commercialized in Europe in 2016 is modified, 26% in the native form, and 55% in the form of sweeteners (Starch Europe, 2017). Another difference is the largest variety of raw materials in the European market, which divides the extraction into three raw materials: corn, with 5 million tonnes of starch in 2016, wheat with 4.3 million tonnes, and potatoes with 1.4 million tonnes (Starch Europe, 2017). Still on a global level, in addition to these raw materials, other crops present the potential for starch production, although some of them on a small scale. Thus, Waterschoot et al. (2015) identified a world production of rice (Oryza sativa L.) starch smaller than 50,000 tonnes. Cereda and Vilpoux (2003a,b) identified the production of arrowroot, sweet potato, and Queensland arrowroot (Canna edulis) starches in China. Malinis and Pacardo (2012) identified the production of arrowroot starch in Indonesia. The Antilles, predominantly in Barbados, supplies the European market with arrowroot starch. Taro and yam are other starchy crops produced in large quantities in the world and could be used as raw materials for starch production. Despite the importance of using starch as an ingredient or additive in food, data on alternative starch production are rare

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and unreliable. Even so, it is possible to evaluate the development potential of these starches based on the data available. Starch has a fast-growing market. To meet this demand it is necessary to have a raw material available in large quantity, mainly for the commodity market. Fig. 4.1 shows the evolution of the production of raw materials used for the production of starch or with potential for this kind of use. Corn, rice, and wheat are the main starchy raw materials for food use and present the greatest growth in recent years, driven mainly by the increase in the world population. From the 2000s onward, corn stood out, with superior growth to other crops, mainly due to the US demand for ethanol, but also because of the growth in the world consumption of meat, mainly in the Asian countries. Potato and cassava are intermediate crops, with less growth than corn, wheat, and rice. Even with a smaller production, they are of great importance worldwide. Despite the similarities between cassava and potato, with very similar starch properties

Figure 4.1 Evolution of the world production of the main raw materials used or with potential for use in starch production, between 1970 and 2016. (Based on data from FAO - Food and Agriculture Organization of the United Nations, 2017b. FAOSTAT. Rome, Italy. http://www.fao.org/ faostat/en/#data.)

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and underground starch reserves, the evolution of production presents different aspects between these two crops. Potato production is more stabilized, while cassava production has steadily increased since the 1970s (Fig. 4.1). Three other crops are of regional importance, focusing on some specific regions, such as sweet potatoes in China, taro, and yams in Africa. The production of sweet potatoes has lost importance in recent years, while taro and yams have remained stable (Fig. 4.1). The production is important to identify the potential of a crop on a global level, but using only this aspect is insufficient. The evolution of the productivity is another important variable to establish the potential competitiveness of a crop. Fig. 4.2 shows Rice (1)

Maize (2)

Wheat (3)

Potato (3)

Cassava (4)

Sweet potato (1)

Yam (5)

Taro (5)

12,0

Tons of dry matter / hectare

10,0

8,0

6,0

4,0

2,0

0,0 1970

1975

1980

1985

1990

1995

2000

2005

2010

2015

Figure 4.2 Evolution of productivity of the main raw materials for starch production in tonnes of dry matter per hectare, between 1970 and 2016. 1, China; 2, United States; 3, average of France, the Netherlands, and Germany; 4, Thailand; 5, world average. (Based on data from FAO - Food and Agriculture Organization of the United Nations, 2017b. FAOSTAT. Rome, Italy. http://www.fao.org/faostat/en/#data.)

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the evolution of the productivity of the main raw materials for starch production, in tonnes of dry matter per hectare, in the largest starch-producing countries for each crop. The analysis was based on dry matter and not on starch, since other components, such as gluten in wheat and proteins and oil in corn, can be important coproducts for starch companies, increasing the competitiveness of the raw material. Despite the stagnation of world production, the potato is the raw material that produces more dry matter per hectare, with a clear evolution since the 1970s. Hence, potatoes are the only crop that exceeds 10 tonnes/ha of dry matter (Fig. 4.2). Corn and cassava come in second and third, respectively, with approximately 9 tonnes of dry matter per hectare. Wheat is in fourth position, with 7 tonnes/ha. The sharp productivity fall of this crop in 2016 is explained by climatic problems in Europe. Other crops with a productivity of around 6 tonnes of dry matter per hectare are rice and sweet potato, which also show great evolution since the 1970s. Finally, yams and taro produce between 2 and 3 tonnes of dry matter per hectare but have been stagnant since the 1970s. The increasing productivity gap between these two crops and the others indicates a loss of competitiveness, which restricts the use of these raw materials for the production of starch in the commodity market. Despite the higher productivity of dry matter per hectare, potato presents high moisture (Table 4.2), requiring 3.5 times more raw material for the production of the same amount of dry matter than corn, wheat, and rice. In addition to high moisture, the potato has a narrow harvesting period of only a few months per year, which increases the idle capacity of companies. These factors explain why, despite the high agricultural productivity, the world production of potato starch is much lower than that of corn. Cassava, like all plants that accumulate starch in subterranean organs (corms, roots, tubers, and rhizomes), presents high moisture, but in a smaller percentage than potato. It is also a

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Table 4.2 Percentage of dry matter in the main raw materials used or with potential for use in starch production Raw material % Dry matter

Wheat Rice Corn Cassava Taro Arrowroot Yam Sweet potato Potato

89 88 88 40 40 30 29 26 25

Source: From the authors.

crop that can be harvested all year round, despite seasonal variations in dry matter and starch content, which lowers storage costs and allows starch companies to run during all months of the year. Table 4.2 identifies two groups of raw materials for the production of starch. The first group is composed of cereals, with a high content of dry matter and which can be stored for a certain period. Roots, rhizomes, corms, and tubers compose the second group, with medium (cassava and taro) and high moisture content (potato, sweet potato, and yam). In this case, the productivity per hectare and the possibility of being processed during the whole year are determining factors for their use in the production of starch. Despite the importance of production data, the price is the most important factor to consider. Fig. 4.3 groups the raw materials surveyed into three groups, based on price in dollars per tonne of dry matter: Raw materials with high prices (sweet potatoes and yams): These are used for food and their prices prevent their use for the production of starch. Without a sharp drop in prices, these crops will hardly be able to serve as raw material for starch production, even in the differentiated starch market.

Starch Extracted From Corms, Roots, Rhizomes, and Tubers for Food Application

Rice (1)

Maize (2)

Wheat (3)

Potato (4)

Cassava (5)

Sweet potato (1)

Yam (6)

113

Taro (6)

2500

US $ ton dry matter

2000

1500

1000

500

0 2000

2002

2004

2006

2008

2010

2012

2014

Figure 4.3 Average price paid for raw materials to producers, in US$ per tonne of dry matter, between 2000 and 2015. 1, China; 2, United States; 3, France; 4, the Netherlands; 5, Thailand; 6, Nigeria. (Based on data from FAO - Food and Agriculture Organization of the United Nations, 2017b. FAOSTAT. Rome, Italy. http://www.fao.org/faostat/en/#data.)

Raw materials with intermediate prices (potato, rice, taro): These crops have high prices that hinder their use as raw materials for starch production. The production of rice starch comes essentially from by-products less valorized and that are not used in the food industry. The seasonality of potato, its high moisture content, and its high price make it difficult to produce starch from this raw material, which justifies a world production closer to the value quoted by Waterschoot et al. (2015) and indicated in Table 4.1. The majority of potato starch production is located in Europe, where subsidies lower the price effect. Raw materials with low prices (corn, wheat, and cassava): These three raw materials are the most important for the production of starch, together with potato, which has a higher price.

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Price is the main competitive factor in the starch commodity market and is largely influenced by agricultural characteristics. However, a starch can compete in the international market despite being more expensive, as for potatoes. In this case, commercialization is based on specific characteristics of the potato starch, such as neutrality of taste and color. According to Teagasc (2017), potato starch is very neutral in taste, so the taste of other ingredients in dairy or bakery products is not influenced. This characteristic is also present in cassava starch, which explains the great growth of starch production from it in recent years. Other factors to consider in addition to price are the production of dry matter per hectare and the possibility of production during the whole year (cassava), or at least with the possibility of storing the raw material (wheat, corn).

4.3 CROPS THAT STORE STARCH IN UNDERGROUND ORGANS As seen in Section 4.2, the world commodity starch market is supplied by four crops: corn, wheat, potato, and cassava. Although two of them are native to South America, the potato as it is produced today in the Northern Hemisphere has little in comparison with the original plant, since it was modified enough to meet the demands of developed countries. In addition to these, other crops stand out for their potential, taking into account two agricultural production variables, productivity and dry mass content. Sweet potato stands out in Asia because it presents commercial-level cultivation, but it also shows potential for production throughout the Americas, and even in the United States. Potato production is in the same situation. Taro and yam are important crops in Africa, but in South and Central America, they are considered as just simple food crops. Finally, cassava is an important crop in the Americas. Sections 4.1 and 4.2 identify a large space that could be occupied by special starches, with differentiated prices. In this niche,

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it would be possible to cite arrowroot starch (see Chapter 5); however, even for starches with a recognized potential of commercialization, there are difficult issues to solve. Therefore, there are plants that are already specialties as commercial crops and many others that show potentiality due to the characteristics of their starches, but they still depend on meeting agricultural yield and the minimum dry mass content required. The question is how to make a raw material a reliable source of special starch. First, you must prove that your starch has properties that are recognized as specific and valorized. Chapter 5 shows that although many characteristics can be measured accurately, comparisons with literature data are hampered by variations in plant materials; in the extraction, purification, and drying of the starch; and in the analysis methodologies. The general characteristics of starches can be found in Chapter 1, and the characteristics of modified starches are available in Chapter 8. So, to be consistent with the goal established in Chapter 4, only the properties of starches extracted from raw materials that store starch in underground organs will be presented here. The literature shows the main differences of the starches extracted from underground raw materials relative to the pasting properties of starch obtained from cereals, such as the high and sharp peak viscosity, a great viscosity drop, the low paste temperature, and the retrogradation tendency (Hoover, 2001). These characteristics may be due to the crystallinity (Smith and Martin, 1993; Smith, 2001) and the high presence of residues of organic phosphorus (Hizukuri et al., 1970; Tabata and Hizukuri, 1971).

4.3.1 Plants Capable of Storing Starch in Underground Structures The interest in starch extracted from alternative sources comes from the fact that commercial starches available in the Northern

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Hemisphere are scarce, despite all the efforts of institutional research or private companies. They present little variability in composition and other properties, and it is more difficult to obtain starches with different properties, except for genetic modification (GMOs), which in turn does not have the confidence of most consumers. The ancient cultivation of plants capable of storing starch in subterranean organs is proven by archaeological research on the extraction and identification of granules of starches and phytoliths in ceramics, rocks, and other artifacts. It also helps to identify the centers of origin and domestication in the Americas, Africa, Asia, and Oceania (Perry, 2002; Chandler-Ezell et al., 2006; Piperno et al., 2000; Robert and Rosen, 2009). Another relevant aspect of plant domestication is related to the cultivation and selection carried out by women from the wandering tribes. These plants were used in human and animal feeding, for fiber extraction, and for medicinal purposes (FAO, 1994). A grouping systematization between the main crops and their respective origin centers allows differentiating the vegetable classes relative to the type of storage organ in monocotyledonous and dicotyledonous plants. The main starchy plants with underground storage organs have roots, rhizomes, corms, or tubers and Asia as their main center of origin. They belong mainly to the Araceae, Dioscoreaceae, and Zingiberaceae families. A larger diversity of dicotyledon families is native to the American continent and is represented chiefly by the families Fabaceae, Lamiaceae, Solanaceae, and Euphorbiaceae, among others. Among the species of tuberous plants cultivated today with their center of evolution in the African continent and Oceania are the Solanaceae, Euphorbiaceae, Dioscoreaceae, and Zingiberaceae. Most of the tuberous species from Africa display corms as their starch storage organ. Some of these plants are poorly studied and used only as food. The main species capable of storing starch in underground structures are shown in Table 4.3.

Starch Extracted From Corms, Roots, Rhizomes, and Tubers for Food Application

Table 4.3 Species capable of storing starch in underground organs and their center of origin Storage Botanical family Botanical name organ Place of origin Monocotyledons

Araceae Araceae Araceae

Alocasia macrorrhiza L. Schott. Amorphophallus aphyllus (Hook.) Hutch Amorphophallus campanulatus (Roxb.) ex. Decne Amorphophallus konjac (K. Koch) Amorphophallus paeoniifolius (Dennst.) Nicolson Colocasia esculenta L. Schott. Cyrtosperma chamissonis (Schott.) Merrill Xanthosoma sagittifolium L. Schott.

Agavaceae Cannaceae Cannaceae Cyperaceae Cyperaceae Dioscoreaceae Dioscoreaceae

Cordyline terminalis L. Kunth. Canna edulis (Ker. Gawl.) Canna indica L. Eleocharis dulcis (Burm. f.) Trin. ex. Hensch. Cyperus esculentus L. Dioscorea alata L. Dioscorea bulbifera L.

Corm Rhizome Rhizome Corm Tuber Corm Tuber

Araceae Araceae Araceae Araceae Araceae

Corm Rhizome Rhizome

Asia and Oceania Africa Asia

Rhizome Rhizome

Asia Asia

Corm Corm Corm

Asia Asia South and Central America Asia and Oceania South America South America Asia Pantropical Asia Africa and Asia

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Continued

Dioscoreaceae Dioscoreaceae Dioscoreaceae Dioscoreaceae Dioscoreaceae Dioscoreaceae Dioscoreaceae Dioscoreaceae Marantaceae Marantaceae Zingiberaceae Zingiberaceae Zingiberaceae

Dioscorea cayennensis (Lam.) Dioscorea dumetorum (Kunth.) Pax. (Lasiophyton) Dioscorea esculenta (Lour.) Burkill. Dioscorea hispida Dennst. (Lasiophyton) Dioscorea nummularia (Roxb.) Dioscorea opposita Thunb. (Enantiophyllum) Dioscorea pentaphylla L. Dioscorea rotundata (Poir.) Dioscorea trifida L. Tacca leontopetaloides L. Kuntze Maranta arundinacea L. Calathea allouia (Aubl.) Lindl. Curcuma longa L. Curcuma zedoaria (Roxb.) Zingiber officinale L. Roscoe

Corm Tuber

Africa Africa

Tuber Tuber Tuber Tuber Tuber Tuber Tuber Tuber Rhizome Rhizome Rhizome Rhizome Rhizome

Asia and Oceania Asia Asia Asia Asia Western Africa South America Asia South America South America South Asia Asia Asia

Arracacia xanthorrhiza (Bancr.) Helianthus tuberosus L. Polymnia sonchifolia (Poeppig and Endlicher) H. Robinson

Root Tuber Tuber

South America America South America

Dicotyledons

Apiacaeae Asteraceae Asteraceae

Starches for Food Application

Dioscoreaceae Dioscoreaceae

118

Table 4.3 Species capable of storing starch in underground organs and their center of origindcont'd Storage Botanical family Botanical name organ Place of origin

Ullucus tuberosus (Caldas) Lepidium meyenii (Walp.) Ipomea batatas L. Lam Ipomea transvaalensis Manihot esculenta Crantz Pachyrhizus ahipa (Wedd.) Parodi Pachyrhizus tuberosus (Lam.) Spreng Pueraria lobata (Willd.) Ohwi Pachyrhizus erosus L. Urb. Psophocarpus tetragonolobus L. DC Tylosema esculentum (Burch. A. Scheib.) Plectranthus esculentus (N.E.Br.) Plectranthus rotundifolius (Spreng.) Solenostemon rotundifolius (Poir.), J.K. Morton Nelumbo nucifera (Gaertn.) Mirabilis expansa (Ruiz and Pav.) Standl. Oxalis tuberosa (Molina) Solanum tuberosum L. Solanum andigenum ( Juz. and Bukasov.) Solanum juzepczukii (Bukasov.) Tropaeolum tuberosum (Ruiz and Pavón)

Source: From the authors.

Tuber Tuber Root Root Root Root Root Root Root Root Root Tuber Tuber Tuber Tuber Root Tuber Tuber Tuber Tuber Tuber

South America South America South America Africa South America South America South America Asia Central America Asia Africa Africa Africa Africa Asia South America South America South America South America South America South America

Starch Extracted From Corms, Roots, Rhizomes, and Tubers for Food Application

Basellaceae Brassicaceae Convolvulaceae Convolvulaceae Euphorbiaceae Fabaceae Fabaceae Fabaceae Fabaceae Fabaceae Fabaceae Lamiaceae Lamiaceae Lamiaceae Nelumbonaceae Nyctaginaceae Oxalidaceae Solanaceae Solanaceae Solanaceae Tropaeolaceae

119

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Starches for Food Application

4.3.2 What Differentiates the Starches Extracted From Underground Organs? Full information on the general properties of starches is given in Chapter 1. In this chapter, the information will be more restricted to that which characterizes the starches obtained from roots, corms, rhizomes, and tubers, or that information that differentiates or valorizes them, with a focus on food preparation. The focus on starchy plants that store starch in modified underground stems such as roots and rhizomes (Heredia-Zarate and Vieira, 2005; Costa et al., 2008; Daquinta et al., 2009) is because their potentials are still little explored. In relation to the composition of the storage organs, it is possible to generalize and say that they present more than 60% moisture, with low levels of nutritional components such as proteins, fats, minerals, etc. However, according to Buléon et al. (1998), in addition to carbohydrates, the starches extracted from these sources may contain small amounts of accompanying substances that modify or influence the characteristics and properties of starch in a drastic manner, among which phosphorus stands out. If the composition of the storage organs is similar, there may be differences in the comparison between the raw materials. Table 4.4 compares analyses conducted using the same methodology. 4.3.2.1 White Color Is a Distinctive Feature of Starches The starches of any botanical source are white, tasteless, and odorless powders, a characteristic that is highly valorized in some food applications. However, there is not much information in the literature on starch color. Only the residual substances originating in the storage organs can explain color, smell, or flavor in the extracted starch and the presence of these residues is little reported in the literature. The method of industrial extraction includes starch purification in centrifuges (Vilpoux, 2003). In the presence of secondary compounds in starches from tubers can also be characterized by

Botanical name

Moisture

Starch

Sugar

Ash

Protein

Lipid

Fiber

Curcuma longa Maranta arundinacea Ipomoea batatas Canna edulis Dioscorea sp. Arracacia xanthorrhiza

81.23 68.20 67.73 75.67 75.30 79.70

8.83 24.23 14.72 18.45 20.43 15.17

2.02 1.08 6.99 0.83 1.19 1.34

2.01 1.83 1.33 1.67 1.12 1.03

2.02 1.34 1.33 1.09 0.13 0.56

0.91 0.19 0.35 0.33 0.12 0.20

1.78 1.44 1.39 1.00 0.77 1.15

Based on Cereda, M.P., 2002. Importância das tuberosas tropicais. In. Cereda, M.P. (Ed.), Agricultura: tuberosas amiláceas Latino Americanas, vol. 2. Cargill, São Paulo, cap. 2, pp. 13e25.

Starch Extracted From Corms, Roots, Rhizomes, and Tubers for Food Application

Table 4.4 Comparison between the compositions of underground storage organs, in percentage of fresh mass Grams per 100 grams fresh mass

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Starches for Food Application

the presence of aroma, as is noticed in the starch obtained from ginger and Curcuma zedoaria. 4.3.2.2 The Crystallinity Pattern Is Also a Distinctive Feature of Starches In all starches, the granules are arranged in a semicrystalline state that is composed of amylose and amylopectin. The structure of the starch granules is related to the arrangement of the amylopectin chains, organized in different ways depending on the botanical source and stage of granule formation, suggesting a classification of chains as A, B, and C (Wang and White, 1994; Parker and Ring, 2001). Type A consists of a chain of glucose attached by unbranched a-D bonds (1 / 4) with no ramification, presenting a nonreducing end, and which is attached to a type B chain through a-D (1 / 6) bonds. According to Tang et al. (2006), type B chains include several A-type chains, but may also contain type B chains attached by a primary hydroxyl group. The C chain is a single amylopectin molecule composed of a-D (1 / 4) and a-D (1 / 6) bonds, with a terminal-reducing group (Parker and Ring, 2001; Vandeputte and Delcour, 2004). The crystallinity in storage organs, such as roots and tubers, comprises structures with the B-type distribution pattern, composed of basic units of double-helix packing chains, counterclockwise and parallel aligned, generally described as having greater resistance to digestion (enzymatic or acid). In addition, some plants of the Fabaceae family present starch with an intermediate structure between the A and the B patterns, which is known as the distribution pattern type C (Eliasson, 1996, 2004). 4.3.2.3 Shape and Size of Starch Granules as Indicative Scanning electron microscopy provides information regarding the size and shape of starch granules. The size of starch granules can vary from 1 to 100 mm and they present different forms depending on their botanical source (Coultate, 2004). The size and shape of the granules vary with the species, whereas the size

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distribution varies with the stage of development of the plant and form of tuberization (Ferrari et al., 2005; Matsuguma, 2006). Vandeputte and Delcour (2004) and Tester and Karkalas (2004) state that the starch granules obtained from cereals are polyhedral and triangular, while starch granules from underground organs present circular and oval shapes, and they can be flattened or not. 4.3.2.4 Influence of Plant Genetics on the Starch Characteristics It is known that the genetics of certain cultivated plant strains give specific characteristics to the properties of the synthesized starches (SSs). The biotechnological research approaches to this subject are carried out mainly in cereals such as corn and rice and potato (Tester et al., 2006; Streb and Zeemana, 2012). The expression of allosterically insensitive ADP-glucose pyrophosphorylase has not been used only in rice (Toyosawa et al., 2016) and corn (Wang et al., 2007), but also in wheat (Smidansky et al., 2002) and cassava (Ihemere et al., 2006). Therefore, changes in the expression of an SS gene can lead to complex effects. This is exemplified by the results obtained using transgenic potato plants expressing a bacterial synthase whose tubers accumulated less starch, but with altered structural properties (Shewmaker et al., 1994). Ceballos et al. (2007) obtained cassava clones through cross-pollinated matrices, resulting in heterozygous F1 genotypes (Wx wx) for the mutation and, therefore, ones that were free of amylose, due to the nonexpression of genes that would result in the formation of SS enzymes, further showing the effect on the functional characteristics of the starch gels. This variability can also occur in the case of plants resulting from sexual reproduction. Cassava is commercially cultivated with vegetative stem cuttings. However, in the screening of the results of the analysis of starch isolated from five cassava landraces collected in indigenous cultivation areas in the

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Brazilian Amazon, the starches sampled differed in pasting properties, as reported by Akuzawa et al. (1999), probably because of the variability of plants that developed from seeds. 4.3.2.5 Organic Phosphate Content in the Starch Structure At the level of molecular structure of the starch, Noda et al. (2005) report that phosphate groups are covalently bound to amylopectin molecules and can be isolated from root and tuber crops, as in potato starch, which has a large amount of phosphate, which guarantees the potato a high degree of phosphate substitution. Although the pasting properties of the native starches obtained from underground organs are well established, it is important to remember that in the plants of the family Zingiberaceae, the organic phosphorus residues that may be associated with the molecules of amylopectin count as a differential (Hizukuri et al., 1970; Tabata and Hizukuri, 1971), explaining the properties of these starches. 4.3.2.6 Technological Properties and Relations to Industrial Applications 4.3.2.6.1 Pasting Properties of the Starch Extracted from Underground Organs

The starch pasting properties generally occur in a variable temperature range depending on each starch source or modification type (Eliasson, 1996; Weber et al., 2009), but always lower for the starches extracted from underground organs than for cereal and legume starches. The main characteristics of the gels that determine their use are the viscosity peak and the retrogradation tendency. The starch pasting characteristics were traditionally established in arbitrary Brabender units, requiring samples of more than 25 g starch and taking 2.5 h to make a viscogram. The Rapid Visco Analyser (RVA) has replaced Brabender units, allowing the production of viscograms in half an hour with only 5 g of

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starch. This device defines the same critical points of the gel as the Brabender apparatus but establishes small differences. While the RVA details the initial heating cycle better, the Brabender details the cooling cycle, both being very important to evaluate the performance of a starch sample. In the case of the starches extracted from underground organs, a low retrogradation tendency is expected because of the lower apparent amylose content. However, a viscogram alone is not enough to define the technological properties of a starch. During food preparation, the starch is subjected to stress conditions, which also occur when frozen and refrigerated foods are heated for consumption. The technological properties of a starch, defined by the type of stresses it undergoes during food preparation, such as cold storage (refrigeration and freezing), mixing and agitation, heat sterilization, and reheating, among others, establish its applications (Weber et al., 2009). When starch is not appropriate for a type of food, these characteristics can be adjusted by the use of modified starches, which are subjected to chemical, physical, and enzymatic treatments or their combination (Aplevicz and Demiate, 2007). Precisely, what is wanted in alternative starches are these special characteristics without the need for modification. The characteristics depend on the granules’ shape and size, transparency and opacity, pasting properties such as gelatinization and retrogradation, and technological properties: solubility, swelling, water absorption, syneresis, and rheological behavior of their pastes and gels (Srichuwong et al., 2005; HernándezMedina et al., 2008). The rheological properties of the different starches may vary according to the granule structure and physicalechemical composition, but mainly by the botanical origin (Singh et al., 2003; Srichuwong et al., 2005). The granule size affects the starch composition, pasting and gelatinization properties, baking characteristics, crystallinity, and filling power (Ando et al., 2002), which define the technological properties responsible for specific characteristics of some foods.

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These characteristics may be partly explained by variations in the size of the granules and their percentage of distribution in the starch (Molenda et al., 2006; Peterson and Fulcher, 2001), and in this characteristic, the starches extracted from underground organs present greater variability. According to Leonel (2007), the size and shape of starch granules are among the factors that define the technological properties of starches extracted from underground organs, citing that small granules (2 mm) can be used as fat substitutes because of their size, which is similar to that of lipid globules. The extraction was the same for all botanical sources, and different starch grain shapes and sizes were found. For the analysis of granule shape, a scanning electron microscope was used, with the samples suspended in ethanol and metallized with gold. For the size measurements, the samples were suspended in a solution of water and glycerol, and examined under optical microscopy, with 500 size measurements (smaller diameter, larger diameter, and differences between diameters) by botanical source. The results showed different shapes of the starch granules for the studied tuberous plants. For example, Xanthosoma sp. showed the smallest (12.87 mm) and Queensland arrowroot (C. edulis) the largest granule size (56.61 mm). This variation does not occur for cereal starches, considering rice starch as the smallest, potato starch as the largest, and the other botanical sources presenting medium-sized granules. Molenda et al. (2006) determined the granule size distribution, as well as the direct shear and uniaxial compression testing, for starch extracted from potato, wheat, corn, cassava, and amaranth. The classification of materials based on the results of mechanical testing was in close agreement with the classification based on morphology. Potato and wheat starches that had relatively large granules of 41.5 and 20.2 mm and bimodal particle size distribution showed stressestrain curves with fluctuations, particularly high in the case of potato starch. Cassava and corn starches had smaller granules of similar sizes of

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15.6 and 13.8 mm, respectively. The uniaxial compression stressestrain curves of the two materials were also very similar, as well as their angles of internal friction. The authors compared these starches with amaranth (leguminous) starch, which presented granules of 3.0 mm and that were several times smaller than those obtained from corn and cassava starches for size in micrometers, with 50% of the samples displaying 50% smaller and 50% displaying larger granules. As a result, amaranth starch was characterized by relatively weak compressibility and flowability, the lowest of all the materials tested. Upon heating of an aqueous solution of starch, an irreversible process known as gelatinization occurs at a certain temperature. During heating, the hydrogen interactions between the amylose and the amylopectin chains are broken and the starch granules begin to absorb water, swelling irreversibly, acquiring larger size than the original. The amylose molecules, which are more soluble, tend to exit the granule, and due to the total dispersion of macromolecules and components, the granule breaks. The temperature in this process is evidenced and known as the pasting temperature (Parkerand Ring, 2001; Thomas and Atwell, 1999; Eliasson, 1996). After paste production, when the temperature of the starch suspension returns to room temperature, a gel forms, which depends on the solution concentration and on the cooling rate. Concentrated solutions that are quickly cooled tend to form gels, while more dilute solutions left at rest tend to precipitate (Hizukuri et al., 1981; Eliasson, 1996). These precipitates are formed because of the tendency to form intermolecular bonds of the linear fraction, which does not happen so readily with amylopectin, in which this association is hampered because of its ramifications. This process is called retrogradation and is accelerated by the freezing of aqueous solutions (Henry, 1985). The retrogradation characteristics of amylose and amylopectin are kinetically different. Amylose quickly retrogrades, showing a strong tendency to associate by forming hydrogen bonds with

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adjacent amylose molecules, forming crystalline structures of double helices when the solution cools, remaining for a long period. On the other hand, amylopectin retrogrades at a much lower rate over a long period of time (Chih et al., 1978; Parker and Ring, 2001; Tharanathan, 2002). Retrogradation is a complex phenomenon and varies according to several factors, such as temperature and storage time, pH, starch source, presence of other components (lipids, electrolytes, and sugars), and processing conditions. It is known, for example, that repetition of freezeethaw cycles drastically accelerates retrogradation and syneresis. Ice crystals formed during the freezing process damage the structure of the product, which causes changes in the texture of the product (hardening of the final product) and consequently in the acceptability and digestibility of the starch-containing foods (Eliasson, 1996, 2004; Tharanathan, 2002). The physicalechemical properties, for instance, the functional properties of starch gelatinization, depend on several factors (Singh et al., 2007). This functional property occurs when there is heating of a starch suspension in excess of water, causing an irreversible transition of the structural conformation of the granules (Parker and Ring, 2001; Singh et al., 2007; Yu and Christie, 2005). The pasting profile of the starch varies with the botanical source or type of modified starch. The main characteristics of the gels that determine their use are the maximum viscosity peak and the retrogradation tendency. The critical points of the gel are defined as the peak viscosity, the time to reach this peak, the viscosity break, the end viscosity, and the pasting temperature. In addition to Brabender and RVA equipment, the use of rheometers has become more frequent in the characterization of aqueous starch paste. Gels exhibit viscoelastic behavior, with tand values varying between 0.001 and 3 (Canevarolo-Junior, 2003). This is due to the faster retrogradation of amylose in relation to amylopectin, with a strong tendency to reassociate by forming

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hydrogen bonds with adjacent amylose molecules, forming crystalline double helical structures when the solution cools, remaining for a long period of time (Bello-Pérez et al., 2006). According to Moorthy (2002), the functional properties of starch extracted from underground organs under stress conditions have never been fully addressed. A review addressing the subject was organized with a description of the physicalechemical characteristics and functional properties mainly of cassava, sweet potato, and other species such as the genus Dioscorea (D. alata, D. esculenta, D. rotundata), arrowroot, and others. 4.3.2.7 Interactions of Starch with Other Ingredients Used in Food In the formulations used to give the health-promoting characteristics of foods, complexity requires the evaluation of starch gels in water, but also of the interactions of starch gels with other ingredients such as proteins, lipids, and nonstarchy carbohydrates (Baker and Rayas-Duarte, 1998). The gelatinization of the starch is influenced by the presence of other compounds that, directly or indirectly, interfere with the water activity and its microstructure (Baker and Rayas-Duarte, 1998). Understanding the interactions between components in the starchesucroseewater system is important to improve the texture and shelf life of products. Sugars play an important role in the gelatinization and retrogradation of starch paste. However, sugars have different effects depending on the type of starch used (Prokopowich and Biliaderis, 1995). According to Spies and Hoseney (1982), sucrose, in interaction with water, limits the availability of water to the starch granule, decreases the water activity of the starch paste, and exerts an antiplasticizing effect with stiffening of the polymer matrix. Ahmad and Williams (1999) and Uedaira et al. (1990) explain the effect of sugar on starch suspensions in terms of inhibition of chain organization. Sugar molecules with equatorial hydroxyl groups (such as sucrose) prevent chain rearrangement, delaying

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the process of retrogradation, making the whole structure weak, while those with axial hydroxyl groups (such as fructose) have the opposite effect. According to Spies and Hoseney (1982), there may be a relation between retrogradation and the number of hydroxyl groups and/or the size of the molecule. The mean number of equatorial hydroxyls (OH) is lower in ribose (2.1) and increases in the order fructose (3.0), mannose (3.3), xylose (3.5), glucose (4.6), sucrose (6.3), and maltose (7.2). In addition to sugar, salt and proteins compete with starch for the water available in the system, affecting its gelatinization. Proteins and starches play an important role in the structure, texture, and stability of the food. As they are rarely found alone in products, knowledge of the behavior of their mixtures is of great interest in applications (Pérez et al., 2006). Proteins affect the gelatinization of the starch by forming complexes on the surface of the granules and preventing the release of amylose and amylopectin from the granules, thereby increasing the gelatinization temperature of the starch. The hydrophilic nature of proteins is another factor that explains the effect of proteins on gelatinization, as the protein also interacts with water, and the availability of water to swell the starch granules is reduced (Summu et al., 1999). Interest in research on polysaccharidee protein systems is due to their numerous applications, such as gelatinizing agents, thickeners, emulsifiers, texture modifiers, and stabilizers in foods, cosmetics, and medicines and in the biomedical industries (Nishinari et al., 2000). A polysaccharideeprotein system of great interest is the whey proteinestarch system, present in foods such as yogurts, puddings, snacks, bread, pasta, and morning cereals. They are the main components of many industrially processed foods, improving their texture and taste properties. Whey proteins are widely used as food ingredients because of their high nutritional value and because they present important technological properties, and their gelatinization properties are considered the

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most important because they have the ability to form stable gels by heating the mixture (Vardhanabhuti et al., 2001). Once the characteristics that differentiate the starches extracted from underground organs from the starches of cereals and vegetables have been established, it remains to discuss other issues that are not related to starch chemistry.

4.3.3 Issues with Commercial-Scale Production As presented in Section 4.2, agricultural production with productivity per area per year has a direct influence on the cost of starch, and therefore its applicability. In this case, the starch extracted from underground organs competes in the market not only with corn, wheat, and rice starch, but also with the starch extracted from the underground organs of another two crops that have already reached a commercial size, cassava and potato. Hence, arrowroot starch was chosen to illustrate the problems. 4.3.3.1 The Arrowroot Case (Maranta arundinacea L.) Arrowroot starch is recognized by the international market as having special properties for use in fine confectionery, in addition to being easy to digest. Regarding the quality of arrowroot starch, the literature indicates that its technological properties place it as an intermediary product between corn and cassava starches. The results of Leonel et al. (2002) agree with this hypothesis. The authors compared the properties of arrowroot starch gels with those of potato and cassava starch by RVA. The results showed that arrowroot starch displays viscosity peak, viscosity break, and end viscosity with intermediate values between the other two starches, with greater proximity to that obtained from cassava. The authors also found that the swelling power of the common arrowroot variety starch starts at 60 C, results that agree with the observations of Leach and Schoch (1959) and Peroni et al. (2006) for cassava and sweet potato.

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However, the production of arrowroot starch presents a major obstacle because the planting material is also the raw material for the extraction of starch. For more details, see Chapter 5.

4.3.4 Issues with Commercial-Scale Starch Extraction The valorization of poorly studied raw materials can cause problems that do not occur with those that are used in commercial processes. The commercial extraction of starch from roots and tubers uses grating under water and rotating sieves to separate the starch slurry from the residual mass (bran). The starch is recovered by decantation or centrifugation. Yam and taro starch extraction is difficult because of the high viscosity of the slurry caused by nonstarch polysaccharides (NSPs), which in turn is valorized as a by-product of both the food and the pharmaceutical industries. A Brazilian company that extracts cassava starch that tried to extract yam starch can exemplify one of these situations. The report revealed two difficulties, the high viscosity of the grated mass and allergic reactions of employees who tried to clean the grated mass retained in the sieves. Moorthy (1991) reports that the genus Dioscorea (D. alata, D. rotundata, and D. esculenta) contains nonstarchy carbohydrates, which increase viscosity, hinder the sieving processes, and increase decantation time. The author also reported that the use of aqueous ammonia solution (0.03 M) improved the yield of Dioscorea and Colocasia starches, while decreasing the yield of sweet potato starch, remaining similar to the other starches, but did not provide values for the effect of this viscosity. To clarify this question, Cereda et al. (2005) evaluated the extraction of yam starch (D. alata) with an average moisture content of 76.0% and starch content of 80.0% in the dry matter. The authors compared several products to reduce the viscosity of the grated mass of yam, in which NSPs strongly increased the viscosity of the extraction water, hindering the starch

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decantation. Extraction with water alone was compared with an oxalic acid/ammonium oxalate (OA/AO) solution as the one with the best results. The results confirmed a starch loss on water extraction of 56%, while after reducing the viscosity, the starch loss was just 11%. These losses may be caused by the presence of the viscous water-soluble NSPs that carried starch granules over into the water. In addition to dragging the yam starch granules, the results showed that this drag was selective in relation to the variation in diameter of yam starch granules, which was more pronounced in the extraction with OA/AO solutions. This method of extraction enabled the recovery of a higher quantity of smaller granules. Yam starch extracted with water has a viscographic behavior in agreement with the literature data, where pastes are described as having good resistance to mechanical disintegration (stability) during gelatinization and high setback values. The pasting profile of starch extracted in the presence of OA/AO, however, compared with the curve obtained for the starch extracted with water only, showed interference in the viscosity pattern. The viscosity profile of starch obtained with water presented a rather sharp peak (193 cP), showing that the internal binding forces are uniform. Starch with the highest viscosity peaks showed the highest viscosity break under heat and agitation, which is considered a normal behavior. The authors had concluded that extraction of yam starch with OA/AO showed the best result, with instantaneous loss of mucilage viscosity upon trituration of the tuber. The extraction was facilitated and considerably faster, providing a recovery of 18%, the highest rate among the tested methods. The nitrogen content present in yam tubers was 2.53 g of nitrogen per 100 g of dry matter. This content was removed by the different extraction methods to different extents. The largest nitrogen content reduction was observed with OA/AO followed by the control (water). This unexpected result showed that the extraction with

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OA/AO could detect nitrogen in the residual mass (bran) and in the extracted starch, providing a nitrogenous starch. The spectrum of starch granule sizes obtained also varied according to the treatment. Results proved that NSPs carry small starch granules over to the wastewater. The smaller starch granules’ diameter varied from 1.9 mm (OA/AO extraction) to 13.5 mm (water and pectinase extractions). The larger diameters varied from 41.0 mm (NaOH treatment) to 67.7 mm (OA/AO). All starches extracted showed an RVA behavior in agreement with the literature for yam starch, but with small differences due to the influence of methods. OA/AO extraction showed the best recovery with 18 g of starch per 100 g of yam tubers, with granular variation, however, interfering with the starch rheological behavior. The authors concluded that the establishment of an efficient extraction process could turn yam into a competitive raw material in the market. When the tubers were digested with an aqueous OA/AO 1/1 solution, it was easier to separate the starch slurry from the residual mass, chiefly because of the viscosity reduction. Once you know the characteristics that differentiate the starches extracted from underground organs from other starches, the next item suggests a methodology to find interesting starches with potential uses.

4.4 HOW TO FIND INTERESTING STARCHES WITH POTENTIAL USES First of all, keep looking, but with a multidisciplinary team to avoid a unilateral vision. Remember that just researching the starch without worrying about agronomic and market aspects will not solve the long-term problem. That is why a multidisciplinary team is important. The search for the use of starches in food is quite promising and challenging because the science of nutrition and processing continues to evolve and requires constant updating.

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The question of how to screen for starches with characteristics that meet the food industry requirements in their current format requires new techniques and methodologies. Although the starch of many underground storage organs (roots, tubers, corms, and rhizomes) has been characterized in great detail on the characteristics of the granules or pasting properties, this information is difficult to interpret because of the variability of plants, starch, and nonstandard analytical methodologies. As discussed earlier (see Section 4.3) the most basic characterization analyses do not differentiate the starches of interest to the food sector. One of the reasons is that starches are analyzed in water, when in reality the application hardly has only starch in water. However, in the development of modified starches, this aspect is taken into account. So, one of the recommendations is to use the tools of conventional analyses, but include other ingredients used in food processing, like salt, sugar, vinegar, proteins, gums, and mucilage. This methodology started to be implemented as an aid to the use of infrared and magnetic resonance imaging. The screening of starches with special properties assumes that there is variability in the characteristics of the same starch in crops that store starch in their underground organs. Still, this is a difficult search and to provide coherent results it is necessary to have a simple and efficient methodology. As an example of the variability that may occur in nature, a multidisciplinary team project evaluated the genetic material of cassava collected in the Brazilian Amazon using the proposed methodology. Using more than 300 varieties, Silva et al. (2002) verified that variability could also occur in the case of plants resulting from vegetative reproduction. Cassava is commercially cultivated using stem cuttings. However, in some Brazilian regions the occurrence of seed production is common. In the case of landraces, this variability is explained by the occurrence of plants that develop from these seeds, which fall on the soil and germinate. In the screening of

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varieties cultivated by the indigenous populations of the Brazilian Amazon, the starches sampled from five cassava landraces differed in relation to their pasting properties, as reported by Akuzawa et al. (1999). A methodology developed by a multidisciplinary team applied to the screening of special starches for use in food is presented in the following. This methodology, as well as unpublished results, may facilitate other researchers in their searches. This evaluation can be divided into three activities, with a later introduction of medium infrared (MIR) screening. First (see Section 4.2), it is important to verify if the plant has productivity (tonnes/ha) and starch content that allow an increase in productivity in the field. Next comes the extraction and drying of the starch under standard conditions. The selected analyses will be presented in the following and include the evaluation of functional properties under normal conditions and under stress conditions. Prior to these three activities, it is important to make sure that sufficient planting material is available to ensure the multiplication of the selected raw materials for future analysis (Fig. 4.4). In the first stage of the screening, only the dry mass evaluation, representing the starch content in the raw materials that store starch in underground organs, can be conducted.

Figure 4.4 Methodology for the screening of special-properties starches and evaluation of technological properties. MIR, medium infrared; NIR, near infrared. (Source: From the authors.)

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This is possible because, as already commented, the dry mass of these plants presents more than 80% of the starch content. The first step of the methodology is to extract the starch under standard conditions and dry it below the paste temperature to avoid alterations in its crystallinity. This starch will be screened by MIR and near-infrared (NIR) spectrometry. To differentiate the starch, the recommended technique is the MIR spectra in the 800e1200 cm 1 wavelength region (Dupuy et al., 1997). In this case, less than 2 g of sample is sufficient. As discussed in Section 5.4, the physicalechemical analysis is not very useful in the case of special starch screening but is valid for comparison with the literature. It can be done using the classical methodology, which uses about 100 g of the raw material, or by NIR spectra. The use of methods that require smaller sample amounts, such as infrared (NIR and MIR) techniques, allows screening with a very large number of samples and with auxiliary statistical analyses such as principal component analysis (PCA). This method also enables one to gain time and resources to obtain a first separation of samples with potential for the application. The proposed method of infrared spectrometry in the medium range (MIR) is based on the literature. Dupuy et al. (1997) pioneered the exploration of starch identification, where MIR spectroscopy allows exploration of the molecular structure as a function of the functional groups present. The authors report that the authentication of food is a very important issue for both the consumer and the food industry at all levels of the food chain, from raw materials to finished products. Corn starch can be used in a wide variety of food preparations such as bakery cream fillings, sauces, salad dressings, frozen foods, etc. Several modifications are made to corn starch in connection with its use in agro-food. Some chemical and physical tests have been devised to solve the problem of identifying these modifications, but all the methods are time consuming and require skilled operators. Corn starches were separated into

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groups related to their modification based on MIR analysis performed on 32 samples of corn starches, classified into four groups: (1) native starches, (2) cold-water swelling; (3) hydroxypropylated and phosphate chemicalemodified starches, and (4) acetylated and phosphateemodified starches. The authors concluded that the use of PCA on Fourier transform infraredeattenuated total reflection spectra allows for partially classifying corn starches into subgroups and offers a new way of classifying samples very rapidly. More recently, Liu et al. (2013) used Fourier transform MIR (FT-MIR) spectroscopy combined with chemometrics techniques for identification of starches (potato and sweet potato starch), indicating that FT-MIR spectroscopy can be used as an easy, rapid, and novel tool to differentiate starches even in mixtures of distinct botanical origins. The article by Dupuy et al. (1997) was a pioneer in the exploration of the identification of modified native starches, but it is difficult to do by the chemical starch composition, consisting substantially of glucose molecules, which hides or makes it difficult to observe the differences between macromolecules. The same problem occurs when using magnetic resonance techniques. When analyzing the results the analyst has difficulty in identifying a few radicals among so many hydroxyls. One technique we are developing is the use of amylolytic enzymes to remove as many glucose molecules as possible. The pattern of action of a- and b-amylases is well established. According to Uthumporn et al. (2010), the enzyme catalysis depends on several factors, but the crystallinity of the starch granules constitutes a physical barrier, which can be overwhelmed by the gelling process, causing enough structural disorder to facilitate the action of enzymes. The specificity of the reaction enzyme substrate can establish the points at which the modification makes the coupling and reactions difficult. For modified starches, these points are related to the type and modification level.

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Unusual types of bonds will block the enzymes and produce different hydrolyzed residues on the starch samples and, as a result, different radicals are highlighted in both MIR and magnetic resonance imaging. Hence, it will be possible to separate the samples that are different into groups and carry out the analyses that lead to the identification of technological properties with these steps. In the evaluation phase of the pasting proprieties under stress conditions, the best solution is to look among commercial modified starches for a reference standard, because after all, if the industry developed a modified starch exactly to serve this segment, one can simply search for it and find a native starch with behavior similar to that of this modified starch. This should be done within each stress condition, which in turn will be related to a niche market: infant food, frozen foods, chilled foods, acidic foods, etc. The consumer will find the standards for good use and conservation in the instructions for use. Using standard starch samples already identified as a profile of interest, such as commercial modified starches, the next step will be to identify why and where this starch is different. Hence, based on the multidisciplinary team experience and literature, the following analyses are suggested: size and amylopectin sidechain percentage, organic and inorganic phosphorus content, and apparent amylose content. In relation to the pasting properties, the analyses suggested are peak viscosity, end viscosity, and paste temperature. Table 4.5 summarizes the most relevant points of the analysis of several starches extracted from underground organs, comparing them with native and modified corn starches; some of them are difficult to find in the literature. As it seems from Table 4.5, the selected analyses were not enough to differ the native corn starch and the corn starch modified to resist freezing stress. However, some native starch samples extracted from underground storage organs, such as the starches of arracacha or Peruvian carrot (Arracacia xanthorrhiza)

2.31 0.32

32.24 20.34

0.270 0.076

19.23 21.37

25.32 28.56

342 450

0.31

0.18.55

0.126

12.63

14.97

128

0.15

17.11

0.070

12.63

15.36

142

0.39

29.99

0.121

42.84

52.90

1725

0.20 0.19 0.18 0.19 0.18 0.16 0.15

16.33 2418 25.02 22.00 21.35 23.64 23.92

0.099 0.092 0.113 0.061 0.079 0.072 0.081

14.11 10.68 10.68 11.66 12.63 10.68 11.66

16.70 1.,66 13.20 14..01 14.82 12.66 14.56

170 95 99 114 131 95 124

Ipomoea batatas

Sweet potato CNPH 292 Sweet potato CNPH 314 Canna edulis Manihot esculenta

Branca Sta. Catarinaa Landrace Dg 100 Landrace Dg 132 Landrace Dg 135 Landrace Dg 163 Landrace Dg 272 Landrace Dg 387

Starches for Food Application

Curcuma longa Maranta arundinacea

140

Table 4.5 Examples of differential characteristics of native starches extracted from plants that accumulate starch in underground organs, compared with a native corn starch and two types of corn starches modified for use in frozen foods Size of granules (mm) Phosphor Amylose COOH Area b Smaller Larger Botanical name (g/kg) (% of starch) (% p/p ) (mm2)

0.31 0.60 0.18

20.38 20.47 14.93

0.112 0.164 0.059

14.57 25.21 16.51

17.29 32.60 20.20

174 575 264

0.09 0.03 0.04 0.23 0.11 0.39 1.51

19.00 17.00 17.00 16.61 24.22 9.00 25.02

0.113 0.180 0.068 0.092 0.130 0.085 0.137

14.01 13.60 13.60 10.10 14.86 8.20 21.29

11.66 15.80 15.92 12.66 17.91 3.19 27.75

117 151 156 93 189 4 424

Zea mays

Native or regular corn Corn modified 1 Corn modified 2 Pachyrhizus ahipa Xanthosoma sagittifolium Colocasia esculenta Curcuma zedoaria a

Local name; corn modified 1 and 2 were different modified starches. g/100g. Source: From the authors. b

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Zingiber officinale Dioscorea alata Arracacia xanthorrhiza

141

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Starches for Food Application

and ahipa (Pachirrizus ahipa), showed values near to those obtained for the corn starch (native or modified) if the higher phosphorus content is not considered. At the end of the research project, these starches were stored in multifill aluminum packages under vacuum to form a starch bank for future studies. The preparation sequence of the sample for MIR or magnetic resonance imaging analysis using enzymes to remove excess glucose is presented next. Samples of 10 g (dry matter) of starch are dispersed in 500 mL of deionized water under agitation and the natural pH is adjusted to the range of 6.0e8.0, as recommended by Novozymes and suitable for the action of a-amylase. The adjustment is made with acetic acid (0.01 M) or sodium hydroxide (0.01 M). The suspension is then kept under stirring in a water bath (Dubnoff TEe053) and, then, 30 mL of the thermal-resistant Termamyl (Novozymes) as recommend by the manufacturer is added when the temperature ranges between 90 and 100 C. The declared activity established by Novozymes is 240 KNU-T/g of a-amylase synthesized by Bacillus licheniformis. After 60 min, the pH of the slurry is adjusted to a range from 4.0 to 4.5 and the temperature to a range from 57 to 70 C. Now 30 mL of AMG Novozymes amylase with activity expressed as AGU 300 mL 1 (glucoamylase synthesized by Aspergillus niger) is added. The suspension remains under stirring at 600 rpm for 60 min according to Novozymes recommendation. To separate the solubilized sugars from the inert residue of the unhydrolyzed material the hydrolyzed sample is put into dialysis bags (Inlab 33 mm  21 mm  30 cm) with a porosity of 25 Å in demineralized water at 4 C for 15 days. Periodic exchanges of deionized water are carried out to eliminate the sugars. The inert residue is recovered by drying in an oven at 50 C with renewal and air circulation. The dried material is subjected

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to spectroscopic analysis by MIR spectrometry. A PerkineElmer Spectrum One provided with attachment at attenuated total reflectance and equipped with a diamond crystal is used for the spectral analysis. Two spectra per sample are collected, with 20 s can sin each repetition, with a resolution of 4 cm 1. The spectral range considered is 4000 to 700 cm 1, enabling one to investigate the molecular structure of the starch (Dupuy et al., 1997).

4.5 THE STARCHES WITH THE MOST POTENTIAL: THEIR ADVANTAGES AND DISADVANTAGES The best- known plants worldwide that store starch granules in underground organs are potato, cassava, and sweet potato, mainly because of the wide possibility of cultivation between latitudes of 45 S and 60 N and 30 S and 30 N. In South America, the Peruvian carrot, Queensland arrowroot, and arrowroot are still outstanding, although only on a small scale, both for cultivation and for starch extraction. One difficulty presented by all these potential raw materials, in relation to cereals and legumes, is that it is not possible to store them because of their high moisture content, although for some of them, such as arrowroot, it is possible to store the rhizomes for up to 15 days. However, as discussed in Section 4.2, starchy crops must reach productivity, high dry mass, and starch content, or have other valorized components such as inulin or gums, which can reduce extraction costs. The following are the main crops that store starch granules in underground organs, in alphabetical order of their popular names, as well as their disadvantages and advantages in relation to these needs. Peruvian carrot or arracachadArracacia xanthorrhiza (Bancr.)

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Starch accumulator underground organ: roots. Portuguese

Spanish

French

Mandioquinha salsa

Arracacha

Celeri

The Peruvian carrot is native to the Andes and is a crop to be cultivated at between 600 and 1500 m of altitude, in cooler regions. It is found in Colombia, Peru, and Bolivia, where the starch is extracted in an artisanal process and where the production of 20 tonnes/ha is possible. It presents about 25% of dry mass with 78% of the starch content. The cultivation is conducted using vegetative buds that are detached from the adult plant, therefore not affecting the extraction of starch (Câmara and Silva, 2002). The starch of the Peruvian carrot is recognized by consumers as being easy to digest, and therefore is recommended for infant food production, as well as for the elderly and convalescent people. However, the Peruvian carrot presents problems that make it difficult to use it as raw material for commercial starch extraction, because it is valued and expensive as a vegetable. Unlike other materials that accumulate starch, the cultivar material of the Peruvian carrot is the shoot of the clumps, so it is not necessary to use the roots, which accumulate the starch, which is an advantage in relation to the cultivation of arrowroot. ArrowrootdM. arundinacea L. Starch accumulator underground organ: rhizome. Portuguese

Spanish

French

Araruta

Arrurruz

Dictame

The world production of this tuberous plant is restricted to commercial crops in the Caribbean, Brazil, and China. The relevance of arrowroot is related to the peculiar characteristics of its starch. The fresh rhizome may contain, according to the

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plant age, more than 20% of the starch content (Monteiro and Peressin, 2002) and 32% of dry mass. Arrowroot is a widely used raw material in China for the manufacture of transparent and very flexible pastes. In the manufacture of these pastes, no extruders are used, as is common for noodles. Small Chinese industries produce the handmade pastes by cooking the starch in a concentration of more than 10% in a boiling water bath, stretching the gelatinized starch blanket in a bamboo structure as if it were a fabric. Still warm, this blanket is cut into thin strips that dry at room temperature (Cereda and Vilpoux, 2003a). Although the starch has internationally recognized quality for specific uses, qualifying it as a special starch, it presents two main problems that restrict its potentiality: the fact that the cultivation material is the same as the raw material for the extraction of the starch and the fact that the quality of its starch has not been fully established yet. The literature points out some clues to explain the properties of arrowroot starch, which would be between those of corn and cassava starch. The literature confirms this hypothesis in part by indicating its technological properties as an intermediary between corn starches and cassava or sweet potato. Regarding the starch quality, the literature demonstrates that the pasting properties (Leonel et al., 2002) are between those of potato and cassava starch, with greater proximity to cassava starch. The swelling power of the common arrowroot variety starch, which starts at 60 C, is among those of cassava and sweet potato starches (Leach and Schoch, 1959; Peroni et al., 2006). However, the largest barrier to its extraction in quantity enough to meet the market at the commercial level is that the same structure that is used for cultivation constitutes the raw material used for starch extraction, making it impossible for this starch to pass from a potentiality to a special starch reality. For further details on this case, the reader is advised to read Chapter 5.

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Cassava or tapiocadM. esculenta Crantz Starch accumulator underground organ: roots. Portuguese

Spanish

French

Mandioca

Yuca

Manioc

Cassava is one of the most promising among the raw materials for starch extraction because it is already commercialized and cultivated in large scale, with the planting, as well as part of the harvest, being mechanized. The disadvantage presented by cassava comes from the fact that it is considered a traditional subsistence food in all the regions where it is cultivated, with the exception of Asia. Thus there is competition between its function as human food and the starch extraction process, and in Brazil, the industries are often at a disadvantage in the purchase of this raw material. An advantage of cassava is that the growing material is the stem, which provides plant clones that maintain the desirable characteristics of the starch. However, in some regions, cassava produces seeds, which may provide genetic variability and starches with different properties (Akuzawa et al., 1999). See Section 4.3.2 for more details. Curcuma or turmericdCurcuma longa L. Starch accumulator underground organ: rhizome. Portuguese

Spanish

French

Açafrão-da-terra

Camotillo

Safran des Indes

This plant is native to Southeast Asia, and India is considered the world’s largest producer, producing an average of 22 tonnes/ha year of rhizomes. It develops well under various tropical conditions, at altitudes ranging from sea level to 1500 m and temperatures of 20e30 C (Govindarajan, 1980; Oliveira et al., 1992).

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Turmeric can be used as a natural vegetable dye because of the color of its tuber. Under optimum climate and soil conditions, it can reach 150 cm in height, with large, oblongelanceolate leaves and oblique veins. Its petioles, gathered at the base, form the pseudostem. The central rhizome may be peripheral, rounded, or ovoid, with secondary ramifications (Hertwig, 1986). This vegetable is propagated vegetatively using these rhizomes, which leads to the limitations cited for arrowroot, yet aggravated because of the high value of the powder obtained from the dried and ground rhizomes. The rhizomes represent the economic interest of the culture, but mainly because of the presence of the dye curcumin and its essential oils and not because of the starch. On a fresh basis, the contents of curcumin can vary from 2.80% to 8.00% and the essential oils from 2.50% to 5.00%, presenting only about 9% starch content (Govindarajan 1980; Leonel and Cereda, 2002). The case of turmeric is similar to that of arrowroot, from the point of view of the limitations of the cultivation material, with an aggravating factor, which is the valorized product. One possibility, in this case, is that the starch is the coproduct and not the main product. In this case, it would be extracted from residues obtained from the extraction of curcumin and essential oils. GingerdZingiber officinale L. Starch accumulator underground organ: rhizome. Portuguese

Spanish

French

Gengibre

Jengibre

Gingembre

Ginger (Z. officinale L.) is a plant native to the Asian continent that can reach up to 150 cm in height. It is an herbaceous plant, with articulated stem, lateral long horizontal rhizomes, and ramifications in the same plane. It is one of the most important condiment plants, valorized at the global level for the

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commercialization of the rhizome for its food and industrial use ( Junqueira et al., 1999; Elpo, 2004). Today it is cultivated in tropical and subtropical areas, with India being the main producer in the world, responsible for 50% of the global production, but not because of the starch, which is not among the main products derived from its rhizome. It is currently commercialized in natura, preserved, crystallized, dried, and powdered, in addition to the high value added to its essential oils ( Junqueira et al., 1999; Elpo, 2004; Negrelle et al., 2005). Assays conducted by Leonel et al. (2005) pointed out that ginger rhizomes may present about 11.5% dry mass and yield 15 tonnes of rhizomes per hectare. Gels from the starch present high stability when subjected to heat under mechanical agitation and low retrogradation tendency. The potential of ginger as a raw material for starch production has the same limitations present for arrowroot. The cultivation material is the same for starch extraction, which is also aggravated because it is an export crop. In the case of ginger, the starch was evaluated, but as a by-product of the supercritical extraction of the active principle (Cereda, 2002; Leonel and Cereda, 2002). PotatodSolanum tuberosum L. Starch accumulator underground organ: tuber. Portuguese

Spanish

French

Batata

Papa

Pomme de terre

Common raw materials in the Northern Hemisphere, potatoes are widely used for the extraction of starch in Europe, despite having an origin in the high Andes. The material available today was adapted to present a higher dry mass, mainly to reduce the fat content in its form of consumption as frying. Despite being one of the most consumed food crops, starch can

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be obtained as a by-product of tuber cutting processes to make french fries and other cuts, being recovered by decantation or centrifugation. In Latin America, more specifically in Peru, under the influence of the Potato Institute, there is an intense effort to extract starch from nonstandard potatoes for use in food. Although branches can propagate it, potato cultivation is conducted via seed potatoes, commercially produced only for this purpose, which circumvents the limiting factor of the competition of the use of the tuber as raw material. Queensland arrowrootdC. edulis or Canna indica L. Starch accumulator underground organ: rhizome. Portuguese

Spanish

French

Biri or cana

Achira

Balisier

The Queensland arrowroot (C. edulis L.) is native to the warmer regions of the Peruvian Andes, reaching up to 2 m in height, with oblongeoval leaves and red inflorescences. It is also known in the Andean countries for its leaves, which serve as packaging in the preparation of food (Montaldo, 1972, Herman and Heller, 1997). The productivity in rhizomes reaches up to 30 tonnes/ha. In some regions of Colombia, companies can obtain up to 300 kg of starch per day, but the yield of the extraction is very low, not exceeding 13% of the weight of the rhizomes. This happens because the processing is done by hand, with most of the machines produced by local artisans in the Andes region, and graters probably cannot fully extract the starch located in the fibrous tissue of the rhizomes (Hermann, 1994; Hermann, 1997). The Queensland arrowroot is widely cultivated in China and its starch is used for making a special pasta, using extruders as used for the production of noodles, but the cut binders are dried in the sun. In the extraction of starch, which occurs in the

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artisanal process, residual water presents a dark color due to its phenolics contents (Cereda and Vilpoux, 2003a). Sweet potatodIpomea batatas Lam. Starch accumulator underground organ: tuber. Portuguese

Spanish

French

Batata-doce

Camote

Patata douce

Sweet potato is one of the crops with the greatest potential for being used for starch extraction, although it is still little explored. It has the advantage of the facility of vegetative multiplication by its branches, preserving the tuber for the extraction of starch or food consumption. Although there is a type of latex that can interfere with the separation in continuous spinning screens, as in the case of cassava roots, its tubers are easy to grate. In relation to any of the raw materials that accumulate starch granules in underground organs, it has an advantage in the production of sweeteners by hydrolyzing the starch, since it presents high levels of thermally resistant a-amylase. Sweeteners are one of the most valued products obtained from the starch, by an expensive process. Leonel et al. (1998) evaluated the extraction of sweet potato starch in a cassava starch extraction facility. The results showed that it is possible to switch cassava and sweet potato in the same industry, with raw material capacity of 400 tonnes/day. The efficiency took into account the composition of the root, starch, and bran, allowing the establishment of the mass balance of the process. It was possible to extract sweet potato starch with quality within the limits required by the legislation, generating a bran with 80% residual starch, which at the time was equivalent to the same industrial extraction of cassava roots. However, sweet potato presented an 18% starch yield with 14% moisture content, while the cassava roots presented a 25.5% yield and 12% moisture content. Still, this option is interesting because

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the sweet potato starch presents characteristics very similar to those of cassava. A limiting factor for the extraction of sweet potato starch is the valorization it presents as a vegetable, but it would be possible to extract it during harvest when there is usually a surplus of production. TanniadXanthosoma sagittifolium L. Schott. Starch accumulator underground organ: corm. Portuguese

Spanish

French

Taioba

Mafafa, ocumo

Taniacoco, cocoyam

Tannia is an herbaceous plant, belonging to the Araceae family. Without an aerial stem, the leaves of this plant appear directly from the primary subterranean corm, corresponding to the stem of the plant. These corms will give rise to the edible lateral roots, which have brown bark and yellow or white spares. It is propagated vegetatively by sections of the main corm or small corms. Tannia cultivation is mainly aimed at the production of leaves for human consumption or animal feed. The rhizomes are consumed cooked but present a problem because of the presence of calcium oxalate crystals, which can hurt the mouth of the most sensitive consumers. It presents in Brazil an agricultural productivity of 30 tonnes/ha and about 80% starch content in the dry mass, which would allow the processing of this tuber as a great starchy raw material (Cereda, 2002). The advantage of tannia in relation to other raw materials is that it is not a much-consumed vegetable and that the leaves are the most valorized product, and in this case, the starch would be the by-product. However, tannia presents the same problem as arrowroot, taro, and yam, since the cultivation is conducted using the corm.

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TarodColocasia esculenta L. Schott. Starch accumulator underground organ: corm. Portuguese

Spanish

French

Taro

Papa china

Chou dachine

The inclusion of taro starch among possible special starches is relevant. Although the profile of the plant as a raw material for starch extraction has the same limitations as the Peruvian carrot, sweet potato, arrowroot, and yam, which directly consumed as food, and therefore have a high price, the characteristics of the starch could compensate for this cost. Taro has the smallest granule size among starches extracted from underground storage organs. This differential could be valorized in the elaboration of substitutes for grease matter (Cereda, 2002) and as a support for spray-drying. Daiúto and Cereda (2006) point out that starches and their enzymatic derivatives (dextrin and maltodextrin) are normally used as chargers in spray-drying processes. In this application, the bulk density is an important characteristic and must be controlled in the dehydrated products of pharmaceutical use. In Brazil, the commercial starches used in this application are obtained from corn and cassava. In addition to these two, Queensland arrowroot and taro starches were selected because they represent granule size extremes and thus make it possible to evaluate the effect of size on the apparent density of dehydrated spray-drier products. In the experiment, the spray was done in a Spray Dryer Lab Plant SD 04, operating under pressure of 6 psi, flow of 7.6 mL/min, and 1-cm beak. The inlet temperature was set at 200 C. Aqueous boldo leaf (Peumus boldus) extract was atomized using the four starches as carriers. The dry product was evaluated in relation to its moisture content, water activity, particle size, and bulk density. The results showed that the size of the starch granules was influenced by the size of the particles of dehydrated boldo leaf extract and

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the apparent density of the final product. The greater bulk density was obtained by the starch of Queensland arrowroot with 694 g/mL, and the smaller bulk density was obtained by the taro starch, which presented 456 g/mL. Corn and cassava starches yielded very close intermediate values of 521 and 582 g/mL, respectively, which also represented the size variation pattern of the starch granules. The authors concluded that both taro and Queensland arrowroot starches, alone or in physical mixtures, could meet the specific density requirements, which is impossible to obtain in commercial starches. YamsdD. alata L., D. esculenta (Lour.) Burkill, D. rotundata (Poir.) Starch accumulator underground organ: tuber or corm. Portuguese

Spanish

French

Inhame

Ñame

Igname

Yam is the popular name of several species of the Dioscorea genus of the Dioscoraceae family, known and consumed worldwide. This genus has approximately 600 species and has representatives all over the world (Pedralli et al., 2002; APG II, 2003). Monteiro and Peressin (2002) state that the species that represent the highest food value and that develop in the temperate regions of Japan and China are of tropical origin except for the Dioscorea japonica Thunb. and Dioscorea opposita Thunb. The production of yam rhizomes is mainly for human consumption, in countries of Africa and Asia, and in the form of soups, cooked with meat, roasts, bread, and other forms. These plant species produce aerial and subterranean tubers or corms, whether perennial or annual. The dry mass content varies from 27% for D. alata, with 27% starch, with starch granules varying from 5 to 50 mm (Monteiro and Peressin, 2002). The case of D. alata starch extraction was used as an example of the difficulties that nontraditional raw materials can cause in

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industrial processes (in Section 4.3.3), highlighting the mucilage (polymucosaccharides) that occurs in this potential raw material. According to the literature, tubers contain several chemical compounds, such as alkaloids, sterols, essential oils, flavonoids, and tannins, as well as various nutrients, carbohydrates, proteins, lipids, vitamins (thiamine, ascorbic acid), and minerals (calcium, phosphorus, and iron) (Dey and Ghosh, 2010; Angayarkanni et al., 2007), which could be recovered to reduce production costs, since they are more valorized than starch. According to Murthy et al. (2009), methanolic extracts (100% and 70%) presented considerable levels of total phenols and flavonols. These authors also described the presence of coumarins, sterols, tannins, and triterpenoids. In addition, Saikia and Konwar (2010) analyzed tubers of taro (C. esculenta), tannia (X. sagittifolium), and elephant foot yams (Amorphophallus paeoniifolius) as potential sources of antioxidants. The species Amorphophallus aphyllus, A. campanulatus, A. konjac, A. paeoniifolius, and C. esculenta are described in the literature as presenting in their composition complex sugars, while Dioscorea species present a series of bioactive compounds of great pharmacological interest, but which may hinder extraction of its starch fraction (see Section 4.3.3).

4.6 FINAL CONSIDERATIONS As discussed in Section 4.2, the market for starch used in food is broad and challenging, with growth expectations directly linked to population growth, but with constant adjustments. This will increasingly require the diversification of starch properties. The world food sector is dominated by influences such as health promotion, use by athletes, and foods of gourmet lines, with varied textures and flavors. The lines that stand out are service to consumers with special needs (foods free of gluten, lactose, fat, etc.); activity/health, with modulated energy foods to release carbohydrates at specific

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moments of physical exercise; and foods that activate certain metabolisms, such as antioxidants, reduced sodium chloride, noncaloric sweeteners, and dietary fiber. For this line, sodium substitutes have been proposed to promote blood pressure reduction, even if the sodium derivatives are much cheaper. A new line of food presents itself to meet the needs of vegetarians, strict or not, who are more and more numerous. Starches must meet all of these niches (Santomauro, 2017), and this will be the opportunity for the new starches since they meet the restrictions highlighted in Section 4.2, which are availability and price. This is important because they will compete with modified starches and other nonstarch ingredients. For example, a characteristic common to all starches extracted from underground organs is high viscosity, which is why they can be used at a smaller percentage in formulations, releasing fewer calories, and can be commercialized at lower prices. Another interesting example is the consumption of cooked sweet potatoes in Brazilian gymnasiums. In relation to the calorific content, the sweet potato is more caloric than the same amount of cooked cassava, but the sweet potato presents a higher sugar content, providing a reserve of energy ready to be used by the athletes before the starch releases more energy by the action of the enzymes of human metabolism. In all these situations, the consumer will always give preference to starches without chemistry. The company Ingredion (Clean label - Ingredion, 2018) highlights a portfolio of more than 25 NOVATION clean label starches to let the customers formulate on-trend, clean-label products in texture and taste across a broad range of applications. The company stands out as a pioneer in clean-label ingredients, and in offering the broadest range of specialty clean-label starch solutions and formulation expertise available. As consumers grow ever more health conscious, clean labels are becoming increasingly important to them. People want to know exactly what is going into their food.

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More recently, the presence of phenolics in foods has been valorized by the antioxidant effect they confer. In this aspect, it is known that some types of starch, such as that extracted from avocado seeds, may be intensely orange, due to the presence of phenolic compounds, which are not removed during extraction with water and only very slightly with organic solvents. The presence of these natural phenolics may provide a new line of starch under the label of health promoters. In relation to the opportunities presented by modified or native starches with special properties, it is important to remember that the search for these starches must follow agricultural experimentation, because of the few available data for decision-making. It is necessary to increase not only agricultural productivity but also the dry mass content, which is directly related to the starch content. Given these considerations, it should be emphasized that the choice of which type of starch from underground organs should be realized by reasons of local criteria, taking into account the advantages and disadvantages they present.

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FAO - Food and Agriculture Organization of the United Nations, 2017a. Food Outlook - Biannual Report on Global Food Markets. Rome, Italy. http://www.fao.org/3/a-i7343e.pdf. FAO - Food and Agriculture Organization of the United Nations, 2017b. FAOSTAT. Rome, Italy. http://www.fao.org/faostat/en/#data. Ferrari, T.B., Leonel, M., Sarmento, S.B.S., 2005. Características dos rizomas e do amido de araruta (Maranta arundinacea) em diferentes estádios de desenvolvimento da planta. Brazilian Journal of Food Technology 8 (2), 93e98. Fuentes-Zaragoza, E., Riquelme-Navarrete, M.J., Sánchez-Zapata, E., Pérez-Alvarez, J.A., 2010. Resistant starch as functional ingredient: a review. Food Research International 343 (4), 931e942. https:// doi.org/10.1016/j.foodres.2010.02.004. Govindarajan, V.S., 1980. Turmeric. Chemistry, technology and quality. Critical Review of Food Science 12 (3), 199e301. https://doi.org/10. 1080/10408398009527278. Henry, R., 1985. A comparison of the non-starch carbohydrates in cereal grains. Science of Food and Agriculture 36 (12), 1243e1253. https:// doi.org/10.1002/jsfa.2740361207. Heredia-Zárate, N.A., Vieira, M.C., 2005. Produção da araruta ‘comum’ proveniente de três tipos de propágulos. Ciência e Agrotecnologia 29 (5), 995e1000. https://doi.org/10.1590/S1413-70542005000500012. Hermann, M., 1994. Arracacha and Achira Processing and Product Development. CIP Centro International de la Papa. Progress report 6310, Quito Ecuador, Mimeograph 8 p. Hermann, M., 1997. Arracacha. Arracacha xanthorrizza bancroft. In: Hermann, M., Heller, J. (Eds.), Andean Roots and Tubers: Ahipa, Arracacha, Maca and Yacon. Promoting the Conservation and Use of the Underutilized and Neglected Crops. Internation Plant Genetic Resource Institute, Germany, pp. 75e172 cap. 3. Hernández-Medina, M., Torruco-Uco, J.G., Chel-Guerrero, L., BetancurAncona, D., 2008. Caracterización fisicoquimica de almidones de tubérculos cultivados en Yucatán, México. Ciência e Tecnologia de alimentos 28 (3), 718e726. https://doi.org/10.1590/S0101-2061200 8000300031. Hertwig, I.F. von, 1986. Plantas aromáticas e medicinais. Icone, Curcuma, São Paulo, pp. 254e265. Hizukuri, S., Tabata, S., Kagoshima, O., Nikuni, Z., 1970. Studies on starch phosphate Part 1. Estimation of glucose-6-phosphate residues in starch and the presence of other bound phosphate(s). Starch Starke 22 (10), 338e343. https://doi.org/10.1002/star.19700221004. Hizukuri, S., Takeda, Y., Yasuda, M., Suzuki, A., 1981. Multi-branched nature of amylose and the action of debranching enzymes. Carbohydrate Research 94 (2), 205e213. https://doi.org/10.1016/S00086215(00)80718-1.

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CHAPTER 5

Starch Valorization From Corm, Tuber, Rhizome, and Root Crops: The Arrowroot (Maranta arundinacea L.) Case

Denilson de Oliveira Guilherme1, Fabiano Pagliosa Branco3, Nuno Rodrigo Madeira2, Vitor Hugo Brito2, Carina Elisei de Oliveira3, Cleber Junior Jadoski3, Marney Pascoli Cereda1 1

Center of Technology and Agribusiness Analysis - Catholic University (CeTeAgro/ UCDB), Campo Grande, Brazil; 2EMBRAPA/Vegetables, Brasília, Brazil; 3Catholic University (UCDB), Tamandaré, # 6000, Campo Grande, MS. 79117-900

Contents 5.1 Introduction. Why Arrowroot Starch? 5.2 The Genetic Variation of the Brazilian Arrowroot 5.3 Botanical Aspects and Rhizome Characterization of Maranta arundinacea Variety Comum 5.4 The Arrowroot Starch 5.4.1 Composition of Rhizome and Arrowroot Starch 5.4.2 Size and Shape of Arrowroot Starch Granules According to the Literature 5.4.3 Pasting Properties of Arrowroot Starch 5.4.4 Technological Properties of Arrowroot Starch 5.5 Commercial Cultivation of Arrowroot: What We Have and What We Need 5.5.1 Challenges to Scale Up Production 5.5.2 Evidence of the Differentiated Quality of the Starch of Arrowroot (Maranta arundinacea L.) 5.6 Arrowroot Extraction Using Small-Scale Equipment

Starches for Food Application ISBN 978-0-12-809440-2 https://doi.org/10.1016/B978-0-12-809440-2.00005-8

© 2019 Elsevier Inc. All rights reserved.

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5.7 The Future: Final Considerations Acknowledgments References Further Reading

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5.1 INTRODUCTION. WHY ARROWROOT STARCH? The Marantaceae family constitutes a group of 530 species with 31 genera (Andersson, 1986; Kennedy, 1977, 1997). About 80% of the known species occur in tropical America, 9% in Africa, and 11% in Asia (Hammel, 1986). As part of the order Zingiberales (Neves et al., 2005; Vieira et al., 2012), the species of Marantaceae have a pantropical distribution and are not found only in Australia. Erdman and Erdman (1984) mention that Marantaceae species are found in South America, Southeast Asia, the Caribbean, the Philippines, and India. Among the starchy plants with potential as raw material for starch extraction, arrowroot (Maranta arundinacea) may be seen as a highlight. It is typical of tropical rainforests and grows mainly along riverbanks and clearings, although it can be found in areas of wetlands with open vegetation and depressions along the roadsides (Costa et al., 2008). Several authors discuss the possible origin and areas of occurrence of this plant. Some authors consider it native of the Antilles, Mexico, or other Central American countries (Bentley and Trimen, 1880), but most accept that it originated in Latin America (León, 1987). According to Arns (2002) M. arundinacea L., the species that presents economic value, is native to the Amazonian forest. Peckolt and Peckolt (1893) state that it is native to Brazil, specifically from Central Brazil, where it is found from the northeast to the south of the country (MAPA, 2010). It is also found natively in the Venezuelan forests (Leonel and Cereda,

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2002), and in the tropical regions of South America (MAPA, 2010). Considering this wide distribution, arrowroot is traditionally processed in several tropical countries for the extraction of starch, which is used in several food preparations (MAPA, 2010). Because arrowroot is not cultivated intensively it is difficult to find records of regular production; there is little literature available and, because it is usually marketed in the production site vicinity, information about the price of the starch extracted is even more limited. Despite the lack of information, arrowroot is not in danger of extinction, but the UN Food and Agriculture Organization ranks it among the neglected crops. The food use of arrowroot starch is very old, as evidenced by the study of plant food preserved in the residues from gourd and squash artifacts. The earliest evidence for the consumption of carob and arrowroot was found in Peru, which provided insights into foods consumed at feasts (Duncan et al., 2009). Similar to other South American starchy plants, such as cassava, sweet potatoes, yams, and taro, arrowroot is considered a rustic, easy-to-grow, and low-cost crop. These characteristics actually occur when the cultivation is handled on a horticulture scale with a low technological level, occupying small areas. However, when cultivation leaves this niche and demands for greater production or higher productivity appear, as well as the production warranty and quality uniformity, these rustic crops present a series of issues that do not exist in small crops. Arrowroot has been widely cultivated in Brazil, but has lost ground since the 1970s, almost reaching extinction. Other starches produced from different raw materials at the industrial level, such as cassava and corn, gradually replaced the cultivation of arrowroot. However, starches obtained from cassava or corn do not present the same characteristics compared with that produced from arrowroot, such as easy digestibility and ability to gelatinize (Silva et al., 2000).

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The abandonment of cultivation came about because, until the years 1940e50 the arrowroot was a crop planted between the lines of corn, which was also grown without much technology. Cultural management was manual or realized by animal traction. From the 1960s on, however, corn production improved and then mechanization arrived, excluding the cultivation of arrowroot, which continued to be cultivated on a small scale, but almost disappearing. Erdman (1986) reports that the extraction of arrowroot starch was then restricted to small plantations in Latin America, especially in Colombia. In the Caribbean and Indonesia, arrowroot culture is valorized for its resistance to typhoons (Malinis and Pacardo, 2012). In the Philippines the cultivation of arrowroot has been valued as a tool for development by groups of women, in regions frequently affected by typhoons (Ancheta and Rosalina, 1988). The fact that it is an old crop does not justify the present interest. Many ancient crops have never been able to sustain themselves. In the case of arrowroot, the difference is the interest in its starch, considered a specialty compared with other starches that are commodities, like corn, wheat, potato, and even cassava. This difference remains over time, although the special quality of arrowroot starch has not been conclusively proven yet. Nevertheless, the number of frauds perpetrated in the Brazilian market by the sale of cassava starch with labels that imply that it is arrowroot starch leads one to suppose that some truth exists in these reports. In Bahia, a Brazilian state located in the east of the country, there is a commercial attempt to produce arrowroot starch and sell it directly to the consumer via the Internet, in small quantities, and at a high price. The authors report in this chapter on the efforts and difficulties encountered by a multidisciplinary team in an attempt to reestablish the cultivation of arrowroot at levels of agriculture to supply the market with two foci: • increased planting scale; • evidence of the differentiated quality of arrowroot starch.

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5.2 THE GENETIC VARIATION OF THE BRAZILIAN ARROWROOT According to Souza and Lorenzi (2005), in Brazil, the Marantaceae family has 150 species, among which the Maranta genus is the second most representative (Costa et al., 2008; MAPA, 2010). Maranta is a neotropical genus, which is found in moist and shaded habitats in forests and in the Brazilian savannah (the Cerrado). Four new species were discovered and described. They are found in dry habitats, frequently near watercourses or occasionally in humid and shaded places, and two of them seem to be endemic to the state of Mato Grosso, Brazil (Vieira and Souza, 2008). In Brazil 12 genera and 150 species occur, with the Maranta genus predominating in the central region of the country (Vieira et al., 2012). Therefore, it would be possible to imagine a large number of varieties available throughout the country, but owing to commercial disinterest in the cultivation of arrowroot, little has been done in Brazil to evaluate this diversity. Several varieties are mentioned in the literature, some of them with a popular denomination, like Comum, Creoula, and Banana. Other varieties receive local names and are not economically important, such as bamboo, giant arrowroot, forage, etc. In Brazil, at least eight varieties, or ecotypes, of arrowroot are mentioned, presenting variations of the morphological characteristics, but mainly related to the size of the leaves and rhizomes; these varieties are known as Banana, Creoula, Guadalupe, Santa Catarina, Seta, Ovo-de-Pata, and the Comum, which has greater commercial interest. Among them there is a variation in the shape of the fusiform rhizomes, which are rounded, long, or arrow-shaped. Marantaceae family plants are easily identified by the combination of leaves with parallel veins and the presence of a thickening called pulvin at the junction between the petiole and

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the leaf blade (Fig. 5.1C). This family presents subterranean rhizomes, except for some species in which the rhizome is aerial, forming an inflorescence with double flowers. Arrowroot is a monocotyledon of fasciculate roots and leaves with parallel veins (Costa et al., 2008). In tropical conditions, it is characterized by little or no flowering (Pio Corrêa, 1984). The Centre for Genetic Resources and Biotechnology (CENARGEN) of the Brazilian Agricultural Research Corporation (EMBRAPA) is responsible for the available material on the propagation of M. arundinacea L., which is dispersed in several regions of the country and kept in cultivation. The CENARGEN reports four introductions for starch extraction, which are Creoula, Santa Catarina, Banana and Comum (Madeira et al., 2013). The variety Comum is commercially more widespread than the others and is considered to produce the best quality starch. Its rhizomes are clear, fusiform, and covered by scales and the plant reaches up to 30 cm, depending on the quality of the soil, although the normal size varies from 10 to 25 cm. It presents petioles differentiated by pulvin, a brilliant peel, scales, and rhizomes produced in tufts adherent to the roots. It has small segments denominated by nodes and internodes, separated by (A)

(B)

(D)

(C)

(E)

Figure 5.1 Morphological aspects of the Comum variety of Maranta arundinacea L. (A) Plant in the vegetative state. (B) Inflorescence. (C) Pulvin. (D) Rhizome. (E) Fasciculated roots. (From the authors.)

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slight bottlenecks, and provided with scales (Leonel and Cereda, 2002; Monteiro and Peressin, 2002; Heredia-Zarate and Vieira, 2005; Madeira et al., 2013). The variety Ovo-de-Pata presents small rounded rhizomes, 2e3 cm long (Madeira et al., 2013). The authors also point out that, in practice, what happens is the selection and maintenance of local varieties, with the systematized identification of arrowroot varieties not occurring. The variety Banana has thicker and shorter rhizomes, with relatively less fiber than the other varieties, and yields between 3 and 4 tonnes of starch per hectare; however, it does not keep well, and therefore it is recommended to extract the starch by 3 days after the harvest (Cecil, 1992). Finally, Creoula is the most resistant variety, but its rhizomes need to be washed several times to lose the dark layer; otherwise, they produce a dark and poor quality starch. Its rhizomes occur in clumps, on the soil surface (Leonel and Cereda, 2002). Although the starch extraction is considered less efficient in the industry, the starch produced by this variety can be extracted within 1 week after harvest (Cecil, 1992). Despite the diversity and ease of recognition, studies that differentiate and classify these varieties are limited. It is known that molecular biology techniques have not ever been applied to differentiate arrowroot varieties. With the advent of molecular techniques, DNA markers have become indicators for the genetic study of various organisms, including plants. These techniques have become routinely applied in research on biodiversity, evolution studies, and biotechnology. Molecular markers are characteristics that identify the profile of a DNA molecule (fingerprinting), which can be inherited and are able to differentiate between two or more individuals (Milach, 1998). The information obtained by means of molecular markers is very useful to help identify contrasting genotypes in plant breeding programs that include different standards for obtaining genetic variability, selection of

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superior individuals, and evaluation of promising genetic materials for trade. In these programs, DNA markers are applied in monitoring and in the organization of genetic variability, an assisted selection by molecular markers that detects genetice molecular differences, representing a promising future in agriculture and plant variety protection (Fukuda et al., 1994; Lee, 1995; Faraldo et al., 2003). The polymerase chain reaction (PCR) allowed the development of several classes of molecular markers that are increasingly used in various plant species. Among these markers, there is random amplified polymorphic DNA (RAPD), or DNA amplified at random (Williams et al., 1990; Baysal et al., 2010). RAPD is based on the amplification of random DNA fragments through single, small, and arbitrary primer sequences that hybridize to DNA and serve as a template for amplification by PCR. RAPD has been extensively used in genetic studies to present in a short period the screening of a large number of samples. It is characterized by being a simple technique, accessible for relatively low cost, requiring no prior information about the nucleotide sequences of the species genome, in addition to being used in any stage of the plant’s development, since the plant is not affected by any environmental factor (Bhagyawant et al., 2015). Using this technique Pinto (2015) analyzed the four varieties of M. arundinacea provided by the EMBRAPA CENARGEN: Comum, Santa Catarina, Guadalupe, and Seta. The identification of M. arundinacea varieties was conducted by the use of the chloroplast genes matK (maturase K) and rbcL (ribulose1,5-bisphosphate carboxylase/oxygenase). The genetic similarity between M. arundinacea varieties was also determined through RAPD molecular markers, by using 25 primers. The longest sequences were amplified with the primers OPA01, OPA02, OPA17, OPA18, OPAF, and OPF05. Among them, the primer OPA02 showed a reproducible pattern of polymorphic bands. The genetic similarity was estimated using the

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Jaccard coefficient with the unweighted pair group method with arithmetic mean test. It was possible to establish two distinct groups among the variations: group I (Comum) and group II (Santa Catarina, Guadalupe, and Seta). To identify the variety, it was also possible to establish the characterization of the chloroplast genes rbcL and matK, by searching the databases BLAST (GenBank) and BOLD Systems, resulting in 99.66% and 100% similarity to the genes matk and rcbL, respectively, in the four varieties of M. arundinacea. The gene carried out by neighbor joining was also used to build a phylogenetic tree and allowed one to observe, after the separation of the outer group, a group containing the accesses Santa Catarina, Guadalupe, and Seta and the bank-donated M. arundinacea (3845927560), which did not present differences among them. Another internal group consisted of the variety Comum and the database variety M. arundinacea (JQ592613.1), showing the presence of a joint difference from the varieties Santa Catarina, Guadalupe, and Seta. Although there is this difference, the data indicate that all varieties are within the species M. arundinacea. The results allow one to infer that the Comum access (variety) was the most divergent, being different from the Santa Catarina, Guadalupe, and Seta accesses, assuming that an evolutionary change may have occurred due to the geographical distance between the cultivation sites, which according to Slatkin (1987) restricts the evolutionary process by preventing adaptation to local conditions and promoting evolution by spreading new genes and gene combinations among populations of a given species. These arrowroot accesses may present genetic variability caused by sexual reproduction with other populations, by genetic mutations, or by natural crosses with plants of different genotypes. The genomic characterization of the four accesses led the multidisciplinary team to continue the research with only the Comum variety during a 5-year project duration, which

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avoided dispersion of efforts. In addition, the other three varieties granted by the EMBRAPA CENARGEN, similar to the Ovo-de-Pata, which was obtained in the region where the project was installed, were gradually lost in the second year of cultivation in the field for several reasons.

5.3 BOTANICAL ASPECTS AND RHIZOME CHARACTERIZATION OF MARANTA ARUNDINACEA VARIETY COMUM Botanically speaking, the Comum arrowroot variety is an herbaceous plant, which presents rhizomes and a type of prostrate stem that grows horizontally under the soil, emitting roots, leaves, and branches from its nodes and giving rise to an intricate complex of small rhizomatous stems near the root system. The rhizome is the raw material used in the process of starch extraction from arrowroot (Madeira et al., 2013). Although Monteiro and Peressin (2002) describe plants of small size, about 60 cm of height, Ferrari et al. (2005) cite plants with an articulated stem of approximately 1.20 m in height, being able to reach up to 1.5 m (Madeira et al., 2013). These variations may be related to different climatic and soil fertility conditions, or field experiments, where small areas are more difficult to homogenize. The rhizomes’ size can vary between 5 and 25 cm long and they present small sections with “scales” (Ferrari et al., 2005; Reddy, 2015). The rhizomes are propagules for the production of new plants, known by the term “rhizome-seed” (Heredia-Zarate and Vieira, 2005; Costa et al., 2008; Daquinta et al., 2009). The multiplication of arrowroot is carried out vegetatively since, in tropical conditions, arrowroot is characterized by little or no flowering (Monteiro and Peressin, 2002). Fig. 5.1 illustrates the Comum arrowroot variety used in field and laboratory experiments. The description of the Comum arrowroot rhizomes found in the literature is superficial. Marsono et al. (2005) describe the

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rhizomes as fusiform and very fibrous. They accumulate starch as a reserve for the development of a new plant and, as a modified stem, they are able to emit shoots. According to Ferrari et al. (2005) the size of rhizomes ranges between 10 and 25 cm, presenting a shiny, scaly peel and produced in tufts adhered to the roots. The differential importance of arrowroot in relation to starches extracted from other raw materials is connected to its special characteristics, allowing it to reach higher prices in the international market compared with similar starches, which increases the interest of the industrial sector in its production (Monteiro and Peressin, 2002). The valorization of arrowroot starch is quite widespread, but little explained. Popular tradition suggests a great variety of uses for arrowroot starch, which is recommended as a food for convalescent or weak people because of its high digestibility (Mason, 2009; Heredia-Zarate and Vieira, 2005; Silveira et al., 2013). However, the direct use of the rhizome as food is unknown, because it is very fibrous. A detailed characterization of the rhizome of the Comum variety is considered very important because few pieces of information were found in the literature and because this is the target organ where the starch is stored and from where it is extracted. Cutter (1987) reports that the cortex of arrowroot rhizomes is formed by regular parenchyma cells, where starch storage occurs, with a thin cell wall, which allows good communication between the cells and thus the compartmentalization of the starch in the tissue. In general, the protection of the rhizome buds is provided by cataphylls. This characteristic was also observed in the species Costus spiralis by Oliveira et al. (1986), showing the presence of a set of suberous cells protecting the external region of the rhizome, part of which may appear in the fibrous residue after the starch extraction.

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Fig. 5.2 highlights the homogeneous arrangement of the lignified elements (fibers) in the cauline cortex. The vascular cylinder is an atactostele of collateral bundles (Fig. 5.3), a description that agrees with the observations made by Oliveira et al. (1986) in the species C. spiralis (Menezes et al., 2005) and in Cyperus papyrus L. and by Prata et al. (2007) in Bulbostylis kunth (Cyperaceae). This characteristic distinguishes arrowroot from other monocotyledon plants, but is common to plants of the same order. The morphological delimitation between the cortical and the vascular regions of the rhizome is clear. In this rhizome, the inner cylinder resembles a meristematic region where a small deposition of starch occurs. It is considered that this region is responsible for the longitudinal growth of the organ, because of the internal presence of conducting vessels, where the presence of tracheal elements (Fig. 5.3C and D) stands out. It is not possible to state from the evidence found that it is the endoderm; there is evidence that the described tissue resembles the pericycle, since it was not possible to detect the presence of a Casparian strip. The presence of endoderm in the rhizomes has been reported in the characterization of Canna edulis (Alonso and Moraes-Dalaqua, 2004; Van Fleet, 1942) and Alpinia

(A)

(B)

Figure 5.2 (A and B) Visualization of the lignified elements in the Comum arrowroot variety rhizome and the disposition of the vascular bundles. (From the authors.)

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(A)

(B)

(C)

(D)

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Figure 5.3 Characterization of the vascular bundle in the rhizomes of the Commom variety. To the Left A - primary phloem, B - fiber bundles, C - metaxylem and D - primary xylem and to the right, the presence of conducting vessels forming scattered bundles in the parenchyma tissue of Commom arrowroot variety, A - fiber bundles B - vascular bundle. (From the authors.)

speciosa L. (Bell, 1980), plants that belong to the same order, Zingiberales, as arrowroot. Fig. 5.3 details the region of vascular bundles in the rhizome of the Comum variety, which, owing to their primary origin (primary meristem), have different cell types, as well as cellulose and lignin dispositions. The presence of isolated fibers can be observed in more detail in Fig. 5.4. The fibers contain the primary phloem and tracheal elements (metaxylem and protoxylem), which are also cited by Simão and Scatena (2001), reinforcing the finding that the rhizomes of the species Heliconia angusta and H. velloziana, both plants of the

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Figure 5.4 Characterization of the vascular bundle in the rhizomes of the Comum variety. On the left, the presence of conducting vessels (A) forming scattered bundles (B) in the parenchyma tissue of the Comum arrowroot variety. On the right, (A) primary phloem, (B) fiber bundles, (C) metaxylem, and (D) primary xylem. (From the authors.)

order Zingiberales, also present isolated bundles of fibers and vascular bundles in the cortex that are collateral with fibers close to the phloem. In the cross section (Fig. 5.4), one can observe the lignin disposition in the tracheal elements of the primary xylem and the fibers that follow the vascular bundles, where these elements are of the helical type. Finally, Fig. 5.5 shows the cortex of the rhizome of the Comum arrowroot variety, especially the presence of starch granules darkened by Lugol. In the parenchyma tissue (starchy parenchyma) the granules are homogeneously distributed throughout the cortex but are reduced as they approach the epidermal tissue, distant only a few cells. According to Tomlinson (1969), starch is abundant in the rhizomes of the order Zingiberales and the granules are usually simple and often flattened, as they also occur in Hedychium sp. From the point of view of the occurrence of starch granules in the Comum variety rhizomes, it can be stated that the highest concentration is found in the parenchyma tissue, which is protected by a cellulosic tissue and presents scattered fiber bundles (Fig. 5.6).

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Figure 5.5 Visualization of the lignin arrangement in the tracheal elements of the rhizome of the Comum arrowroot variety, where A corresponds to the tracheal element (tracheids) and B to the fiber bundles. (From the authors.)

(A)

(B)

(C)

(D)

Figure 5.6 Visualization of the lignin arrangement in the vessel elements of the rhizome of the Comum arrowroot variety, where A corresponds to the vessel element and B to the fiber bundles. E, epidermis; PA, amiliferous parenchyma. (From the authors.)

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5.4 THE ARROWROOT STARCH There is plenty of information in the literature about the composition of the rhizome and arrowroot starch, with descriptions of the size and shape of the granules. However, these numbers are difficult to compare because the information on the material analyzed is sometimes incomplete. There are no data on the name of the variety analyzed, or on the cultivation cycle, or on the methods of starch extraction and drying, etc. In addition, Weber et al. (2009) and Eliasson (2004) remind us that the rhizomes are modified subterranean stems and present variations in the starch granule shape, size, coloration, and technological properties.

5.4.1 Composition of Rhizome and Arrowroot Starch To be selected as raw material for commercial starch extraction, it is necessary to have a high starch content and, therefore, a high content of dry mass. In general, underground organs that store starch are nutritionally poorer than cereals, which also represents fewer by-products with the potential to be valorized, thus reducing the processing cost. In this aspect, cereals have an advantage. As an example, corn allows the commercialization of the oil contained in the germ, the cellulosic shells, and even the water of maceration. Wheat makes it possible to valorize gluten as a coproduct. The fresh rhizome of arrowroot contains about 20% of the starch, higher than the content observed for sweet potato (14.72%) and lower than that of cassava (31.09%) (Pereira et al., 1999; Leonel and Cereda, 2002). Table 5.1 presents the composition of arrowroot rhizomes. Cellulose, protein, sugar, mucilage, mineral salts, and vitamins (b-carotene, niacin, riboflavin, and thiamine) are also mentioned, in addition to starch, as compounds present in fresh arrowroot rhizomes (Martins, 1943; USDA, 2001). However,

% in fresh matter

Humidity

68.20

69.00

Starch Others carbohydrates Protein Lipids Fiber Ash Total fresh matter Total

% in fresh matter 24.23 1.93 1.34 0.19 1.44 1.83 30.96* 99.16

% in dry matter 79.14 10.19 1.59 0.55 2.56 2.85 d 95.88

* refers to data expressed in dry mass, the former were in fresh mass, hence the reinforcement Adapted from Cereda, M.P., 2001a. Caracterização de matérias primas amiláceas. In: Cereda, M.P. (Ed.), Propriedades do amido: Culturas de tuberosas amiláceas Latino-Americanas. Fundação Cargill, São Paulo, pp. 88e100; From the authors.

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Table 5.1 Composition of Comum arrowroot rhizome Compound % in fresh matter

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during the starch extraction, whether in industry or in the laboratory, the soluble components are lost in the water, leaving the starch with only 1%e2% of residual amounts of these components. Minor components such as proteins, lipids, fiber, and minerals may remain in the starch and influence its technological properties. In the extraction of starch, arrowroot has to compete with other raw materials and present competitive advantages (see Section 5.2). Leonel and Cereda (2005) report that, at 14 months, arrowroot rhizomes showed 61.17% of the dry mass and 25%e30% of the starch expressed in fresh mass, its highest value. However, this value was lower than the range of 68%e75% of moisture reported in the literature, since it depends on the variety and planting conditions (Ferrari et al., 2005; Leonel and Cereda, 2002; Malinis and Pacardo, 2012). The moisture content at the point of harvest and storage is crucial to establish the cost of starch extraction. While cereals are dried at 12%e14% moisture content and can be stored for years, rhizomes, tubers, and roots present more than 60% moisture content, which makes their storage impractical. In compensation, they do not need to be soaked in water for water absorption to become soft for the starch extraction. The soaking operation makes the process of extracting cereal starch technically more complicated and expensive than the techniques used in the extraction of starch from underground starchy plants, which can be shredded. On the other hand, the starch extracted from any source has more than 90% of the dry mass represented by carbohydrates insoluble in cold water, in the form of starch granules. The starch extracted from arrowroot rhizomes is a fine, white, odorless, and tasteless powder with characteristics very close to those of the other starches obtained from subterranean organs, such as roots, rhizomes, and tubers (Bernal and Correa, 1994). In addition to the starch content, other compounds are important and should be analyzed, so the starch of arrowroot

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can be considered a special food ingredient. Among these compounds the lipid and phosphorus contents stand out. Lipids are present in higher amounts in cereal starches, in which they are complexed with amylose and affect gelatinization, modifying the rheological behavior of the pasting properties and inhibiting the crystallization of the molecules, thereby reducing setback (Wang and White, 1994). In plants in which starch is stored in underground organs, lipid levels are irrelevant (Hoover, 2001). However, the phosphorus content is a characteristic of the starches produced by the plants of the order Zingiberales, and as clarified by Noda et al. (2005), this compound is present as phosphate groups covalently bound to the amylopectin molecules of the starch chain.

5.4.2 Size and Shape of Arrowroot Starch Granules According to the Literature The starch granules from subterranean organs also present two types of macromolecules, amylose and amylopectin (Vandeputte et al., 2003; Tester et al., 2006), but the shape of their granules is rounded, while those of cereal starches are more angular. Although the size distribution and shape of the granules of the starch obtained from grains are well studied, the starch extracted from underground organs has only a little information on the occurrence of a bimodal distribution. According to Eliasson (1996), Eliasson (2004), and Tester et al., (2006), starch granules are considered large when presenting a size of approximately10 to 35 mm and small when showing a diameter of 1e10 mm. In this aspect, arrowroot starch granules can be classified as large. Cereda (2001a) reports the existence of granules with an ellipsoid shape and a size variation of 7 mm, for the granules of small diameter, and 10 mm, for the larger granules. The same author states that the content of amylose in arrowroot starch is 23.5%. According to Erdman (1986), arrowroot starch granules present an average diameter of 13 mm. Leonel et al., (2002)

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processed arrowroot for extraction and characterization of the starch and found 23.9% of the amylose content displaying round and oval starch granules with a size distribution between 9 and 42 mm, but with a predominance of granules with a diameter of 21 mm. The amylose content of arrowroot starch is also a point that varies with the literature consulted. Ferrari et al. (2005) cite that the amylose content increases with the age of the plant, from 17.9% at 12 months to 20.0% at 14 months of cultivation. The importance of the duration of the production cycle of the rhizomes is emphasized by Ferrari et al. (2005), who followed the development of arrowroot to evaluate the influence of the developmental stage on the physicochemical characteristics of rhizomes, granule size distribution, and properties of the starch. The analysis of the amylose content showed an increase with the age of the plant (18% at 12 months and 20% at 14 months of cultivation). Also, the size of the starch granules increased with the growing cycle. The results showed that between 12 and 14 months, the starch content increased to 21.20 g
100 g but did not differ from the 12-month value; at the same time the fiber content increased significantly to 3.69 g
100 g. Regarding the granule profile, the authors observed in rhizomes harvested at 14 months the largest granule size, ranging from 15 to slightly more than 45 mm, and with a frequency of 25% of the granule showing 30 mm, thus confirming the increase in granule diameter with the growing time. The authors did not report the variety of arrowroot analyzed in this case. The moment of harvest in the production cycle may explain the variation of results found in the literature. Leonel (2007) analyzed the shape and size of starch grains from different botanical species extracted in a pilot extraction plant, aiming to improve the applicability of these species as starch raw materials. The size of the starch grains was determined by optical microscopy, for which the samples were suspended in a solution of water and glycerin. The sizes of 500

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granules were measured to determine the largest and smallest diameters and the difference between them. The arrowroot samples showed a homogeneous distribution, with granules of different sizes and the predominance of granules with the diameter in the range of 20e40 mm.

5.4.3 Pasting Properties of Arrowroot Starch To establish the potentialities of use it is necessary to characterize the starch composition and its functionality. The technological properties of starch application generally require viscosity, consistency, and transparency, as well as other characteristics that allow the differentiation of groups of starches for specific applications. Cereda (2001b) presented the results of Rapid Visco Analyser (RVA) viscograms for arrowroot starch with a paste temperature at 61.0 C; the results showed a viscosity peak of 570, viscosity drop of 430, viscosity breakdown (90 C/30 min) of 375, and setback tendency of 570. Leonel et al. (2002) concluded that arrowroot starch has intermediate values, between sweet potato and cassava, for peak viscosity, viscosity break, and final viscosity; however, the low stirring stability was higher than that observed for the cassava starch gels at the same concentrations. The temperature of the arrowroot starch paste was 67.1 C, with a low tendency to setback, similar to cassava starch gels. The authors observed that the viscograms of arrowroot starch showed no effect of duration of the cultivation cycle for pastes of starch extracted at 14 months or at 12 months. The profiles showed sharp peaks and an accentuated drop in the viscosity before reaching 95 C, revealing a low-shear stability when the hot paste is under stirring.

5.4.4 Technological Properties of Arrowroot Starch The quality of starch is the only commercial reference from arrowroot (Mason, 2009), since the direct consumption of the rhizome as food is not known in the literature. In general, to

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discuss the quality of arrowroot starch it is necessary to remember how the knowledge of the fine starch chemistry has evolved (see Chapter 1). Despite the amount of information obtained since 2008, knowledge of the fine starch structure is still under construction. Native starches were initially separated into two groups: cereal and leguminous starches and starches from underground organs. This division was proposed from the establishment of strongly opposing characteristics of these groups with respect to viscosity, consistency, and setback, which includes opacity/transparency and presence/absence of syneresis. Praznik et al. (1999) defined the technological properties of starch as those that define its application. These properties establish the starch resistance to industrial processes and are obtained from a paste produced with heated water and starch. In the food industry, these properties characterize the resistance to sterilization stresses, cold (refrigeration and freezing), acidity, freezeethaw cycles, shear, and pressure. The first group, composed of cereal and legume starches, exhibits a paste presenting short viscosity, high consistency, intense retrogradation, and opacity, while in general, the paste of the starches from subterranean organs has high viscosity, poor consistency, poor or nonexistent setback, and transparency. Slow freezing may induce the development of a spongy structure or sandy texture, undesirable compared with the initial creamy texture of unfrozen sauces (Ferrero et al., 1993a,b; Navarro et al., 1997). These modifications are attributed to the retrogradation of amylose and amylopectin, and to minimize this problem it is possible to add stabilizers and modified starches (see Chapter 6). Even with the increasing information on the chemical arrangement of the granule structure, only the difference in the percentage of amylose and amylopectin was used to justify the strong differences between the technological properties of native starches from different sources. With the emergence of

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genetically modified starchy plants, it was possible to obtain plants with practically 100% amylose (linear polymer) or amylopectin (branched polymer), known technically as waxy starches, but the technological properties were practically the same as those starches from nonegenetically modified plants. One of the major developments in the knowledge area of starch quality occurred with the amylopectin model as a structure of tree branches (see Chapter 1). From this landmark, the technological properties have come to be considered as a function of the amylopectin side-chain size and, more recently, of the arrangement of these amylopectin side chains as established by Eliasson (2004) (see Chapter 1). The starch granules hydrate themselves, in the presence of water, because of the energy from the heat, and swell to overcome the binding forces between the polymers. Continuing to apply heat, the hydration proceeds and the starch granules expand many times their original volume, imparting viscosity to the pasta (Moore et al., 1984). Under these conditions, irreversible changes occur in the structure of the starch, evidenced by the loss of birefringence and alteration of the Xray diffractogram (Biliaderis, 1991). The double helices in the crystalline regions open and dissociate when the hydrogen bonds are broken. Thus, the gelling and swelling properties are controlled in part by the molecular structure of amylopectin (branched-chain length, branching extent, and molecular weight) and phosphorus content, in addition to the granular architecture, determined by the ratio of crystalline and amorphous regions (Tester, 1997). According to McPherson and Jane (1999), large amounts of monoester phosphate in amylopectin molecules decrease the gelation temperature, while the increase in amylose content decreases gelation enthalpy. Finally, the size of the starch granules is a relevant feature, mainly due to swelling power control. Above the gelation temperature, the expansion process is irreversible because of the loss of the crystalline structure in the expanded gel (Morrison, 1995).

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If the heating continues, the starch granules disintegrate to provide a dispersion of amylose, amylopectin, and fragments of the granules. This is when the maximum viscosity is reached (Moore et al., 1984). The reverse action of gelation is retrogradation, explained by intramolecular association (Ziemba, 1965). When the starch granule paste is allowed to rest, without stirring before or after cooling, the tendency is for intramolecular bonds to be formed, forming a gel. The regions of such bonds on the gels increase in number during the resting period, making the lattice thinner and more compact by several degrees according to the number, size, and distribution of the micellar regions (Hodge and Osman, 1985). The process of heating a starch suspension in excess water causes an irreversible order/disorder-type transition, called gelatinization, which occurs in a temperature range characteristic of the botanical source of the starch. This phase transition can be characterized by an endotherm obtained by differential scanning calorimetry (DSC), a method that measures the breaking of the bonds, but mainly of the hydrogen bonds that stabilize the double helices inside the starch granules, when these are heated in water. DSC quantifies the temperature and energy (enthalpy) involved in the transition from a semicrystalline granule to an amorphous gel (Tester, 1997). Vamadevan et al. (2013) analyzed a native arrowroot starch through DSC and found a DSC of 17.68 J/g and initial, median, and end gelatinization temperatures at 70.4, 76.1, and 83.4 C, respectively. These data indicate longer IB-CLs, which facilitate the parallel packing of splayed double helices and the lengthening of double helices, likely increasing the DH. They concluded that the highest melting temperatures observed for arrowroot starch (type C) are not governed by polymorph type but primarily by the internal structure of the amylopectin, which dictates the optimal packing of the double helices within the crystalline lamellae. Latin America also produces alternative starches, such as that obtained from a plant regionally known in Colombia as achira

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(C. edulis). In Brazil, the starch from arrowroot has been replaced by cassava because it is more productive; however, several species, such as saffron, yam, sweet potato, tannia, ginger, and others, are raw materials with potential for starch production (Cereda 2002). Because its availability on the market is low, it is possible to keep authentic arrowroot starch at good prices, but this is also the reason for frequent frauds. Frauds also occur in other countries, with the use of cheaper starches simulating the most expensive ones, and create uncertainties in the market. In the case of starch mixtures visual differentiation is impossible, and often even laboratory analyses are inconclusive. Liu et al. (2013) report the occurrence of fraud in lotus root powder, a valued product, using the cheaper potato and sweet potato starches. To identify this kind of fraud the authors used Fourier transform mid-infrared spectroscopy combined with chemometrics techniques. The results allow the identification and quantification of starches added to the original product and distinguish between forged and nonforged starches, which do not differ in external validation. Despite the difference in the commercial value, the producer needs to overcome all these limiting factors to earn income from the production of arrowroot starch. One of the limiting factors is the starch extraction. Because arrowroot is cultivated and processed as a craft activity, by employing the machinery used for processing cassava flour its yield is reduced (Silveira et al., 2013). In addition, the craft starch extraction requires physical overload, extended static postures, lifting, and loading of manual loads, and repetitive manual labor, making the manual working conditions often unhealthy and not ergonomic (Barth et al., 2016). The process of continuous and large-scale extraction does not necessarily exclude the supply of raw material by small

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producers. According to Cereda and Vilpoux (2003), Thailand and China can be considered two global examples. Thailand supplies its industry with cassava roots, and in China, it is common for several small producers, with different starchy raw materials that change according to the season of harvest, to supply industries with an installed capacity of 400e800 tonnes of raw material per day. However, this model has not been applied in Latin America yet.

5.5 COMMERCIAL CULTIVATION OF ARROWROOT: WHAT WE HAVE AND WHAT WE NEED One of the reasons arrowroot, which already was widely cultivated in Brazil, has lost ground since the 1970s, almost to extinction, is its competition with other commercial starches such as those obtained from cassava, maize, oats, barley, and wheat (Silva et al., 2000). The method of planting arrowroot using rhizomes or parts of rhizomes is considered the first challenge, since it is necessary to use part of the material used for the starch extraction. This limitation does not apply to cassava, for which the vegetative material is the stem.

5.5.1 Challenges to Scale Up Production Only some starchy crops, such as arrowroot (M. arundinacea), yam (Dioscorea sp.), and Queensland arrowroot (C. edulis), are used as alternative raw materials for starch production, especially in China, where small farmers provide about 5.5e6.0 tonnes of starch per hectare, in line with local agricultural policies. However, these starches are still not appearing in marketing statistics because they are used only in the domestic market, especially in the preparation of food pastes (Cereda, 2001c). In addition to it being difficult to find real arrowroot starch on the market, it is rare to find anyone who grows the plant, which makes the cultivation of arrowroot a good deal. Precisely

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because of the fact that there is no large-scale production in Brazil, it is reported that the market price of arrowroot starch ranges from US$6.5 to US$8.5 per kilo of starch, which represents around US$8550 for a starch tonne. In the international market, arrowroot starch can reach prices even higher (450 g costs about US$22.19). With this potential, the State Secretariat of Bahia, Brazil, invested in the training of producers and in the distribution of seedlings with the intention of invigorating arrowroot cultivation (EBDA, 2013). In Brazil, starch production is composed almost exclusively of cassava and maize, a highly technological crop. Arrowroot cultivation has been restricted to small, increasingly rare areas. With this type of production, it is possible to plant in beds, with organic fertilization and manual cultivation, which includes the harvest. However, this production system is far from allowing industrial-scale processing, even on a small scale. The production potential by area and year varies greatly in the literature, making difficult any comparison. Corbishley and Miller (1984) stated that St. Vincent, in the Caribbean, at that time exported about 800 tonnes of arrowroot starch per year, while Cecil (1992) cited an exportation amount of 3e4 tonnes of starch per hectare. The association of arrowroot roots with mycorrhizal fungi is another technique that must be diffused to increase production by area. The studies of Coelho (2003) showed that about 80% of the roots of arrowroot are naturally mycorrhized, providing the rusticity of this crop. Regarding dry mass and starch content, it is possible to consider an average moisture content of 72%, with 28% of starch expressed in fresh mass (Pereira et al., 1999; Ferrari et al., 2005; Leonel and Cereda, 2002; Malinis and Pacardo, 2012). There is not much information on arrowroot, so the comparison with cassava is inevitable. Cassava starch (Manihot esculenta Cranz) is the main competitor of arrowroot starch and has commercial cultivation already. In Brazil, cassava cultivation is mechanized and the harvest is partly mechanized. The average

194

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yield of the Brazilian cassava production is 14 tonnes/ha, but able to reach more than 20 tonnes in the regions specialized in the production of starch, such as in the states of Paraná, Mato Grosso do Sul, and São Paulo (Vilpoux et al., 2017). Also native to South America, this raw material supplies about 70% of the Brazilian starch extraction industries and, like arrowroot, has an average root moisture of 64%e66%, storing about 31% (dry basis) starch (Cereda and Vilpoux, 2003), but according to the Centre for Advanced Studies in Applied Economics (CEPEA, 2017) its average price is only US$1.0 kg in the industries of Mato Grosso do Sul (Brazil). According to Silveira et al. (2013), arrowroot is cultivated with horticulture techniques. After harvesting, a portion of the rhizomes is destined for new planting areas and the other part for starch extraction (Martins, 1943). Under the cultivation conditions of the CentereWest region of Brazil, problems with diseases have not been reported so far; however, pests should be controlled. The caterpillars that cause defoliation are pests that occur in the vegetative phase of the crop and lead to great losses. The harvesting point has not yet been well defined by the research, but according to traditional knowledge, the harvest is conducted when the leaves enter senescence, being wilted and with a brown color, which then becomes straw-yellow and whitish (Leonel and Cereda, 2002). Monteiro and Peressin (2002) recommend harvest at 9e 12 months of cultivation. According to the literature, the best harvesting period is between May and September, when the plants fall onto the soil because of their tonus loss. In some places, the maximum period for harvesting is established at 14 months after planting. After this time the incidence of rhizome rot increases (Purseglove, 1985), which coincides with the recommendation of Ferrari et al. (2005) and what is justified by the starch quality. Monteiro and Peressim (2002) recommend the cultivation of arrowroot in the early rains, reinforced by Tomielis et al. (2015), who report that in the CentereWest

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region of Brazil the planting can be carried out until the month of January, when the rains are reduced. The recommended planting fertilizer for arrowroot uses a combination of highsolubility fertilizers. More than establishing the harvest period in days or seasons, it is more important to follow the plant physiology. The plant accumulates starch, and at the end of its cycle, it will present its highest content. Therefore, the harvest should coincide with the onset of drought or cold, when the plant cannot grow, but still has sunlight to accumulate the synthesized carbohydrates in some reserve organ (Ternes, 2002). New research is still necessary to reach a great expansion of commercial cultivation of arrowroot as a raw material for the extraction of starch, whether in small- or large-scale production. According to Malinis and Pacardo (2012), it is necessary to optimize the cultivation system, establish germplasm banks to improve the harvest yield for starch extraction, and valorize the extraction products with food fiber (Erdman and Erdman, 1984). Because production yield data are very sparse, even under the conditions of field research, the multidisciplinary team responsible for the project has installed field experiments in the CentereWest region of Brazil, in the city of Campo Grande, Mato Grosso do Sul (20 260 S, 54 380 W, 532 m). All the following information was obtained at this location, with rhizomes of the arrowroot variety known as Comum. To enable the cultivation of arrowroot on a scale big enough to supply a starch processing unit, it is necessary to start with the planting of the material, spacing, and cultural management. The main limitation for the expansion of the cultivated area of arrowroot is that the rhizome is, at the same time, the raw material used for planting of new areas and for starch extraction. If it is possible to valorize the starch extracted, this situation will be even more critical. Therefore, the production of planting material is still a bottleneck for the commercial production of arrowroot.

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Two types of planting material are possible because Maranta’s sexual reproduction does not occur frequently, or when it occurs, it is insufficient to form seeds. The main planting material is the rhizome itself from previous crops, which sprouts and develops root and shoots, reproducing the plant that gave its origin (Fig. 5.7A). The rhizome with shoots can also be cut into smaller pieces, which serve as planting material. However, research results show that this type of planting material is more fragile than the entire rhizome. Fractionation requires treatment with fungicide and is even less efficient owing to the death of the shoots due to dehydration or contamination with fungi. Another type of planting material studied was the rooted stem (leaf sheath and leaves) (Fig. 5.7A), which on an experimental scale anticipated the plant development in approximately 30 days in relation to the development of a seedling originating from a rhizome (Fig. 5.7B). This technique is still in development, with the establishment of a protocol. In any case, the planting of rooted stems is the most promising option to replace the rhizome for cultivation and to improve the productivity for starch production. Under field conditions, plants originating from the stem presented 100% survival, while the plants originating from whole rhizomes or their pieces obtained a survival rate of only 73%. Tissue culture was also used in an attempt to avoid the use of rhizomes in the cultivation of arrowroot, but the material became contaminated with molds that were difficult to control (Guilherme et al., 2017). The planting methodology consisted of rows for allowing mechanized harvesting. This type of planting facilitates mechanized management and rhizome recovery. Arrowroot plants grow slowly for 90 days, regardless of the cultural practices used, increasing rapidly their growth in the following months until reaching the maximum development of the rhizomes between 270 and 300 days after planting. If they are not harvested, the rhizomes will sprout with the following rainfall season, beginning a new production cycle.

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Primarily, the whole rhizome, with an average weight of 60 g, was the best recommendation for planting arrowroot (Heredia-Zarate et al., 2005), but the results obtained by the team (Guilherme et al., 2017) show that the best results in field cultivation are with rhizome-seeds greater than or equal to 30 g, half of what was recommended. Also, the planting conditions were changed. The results obtained in field experiments recommend planting the rhizomes or their basal part (the thinner part of the larger rhizomes) arranged in a longitudinal position in pits 20 cm deep, spaced 30e40 cm, and with 80 cm between the rows. Around 3125 to 4170 seedlings per hectare are required in this planting arrangement, yielding an average of 10 rhizomes per plant, and with a maximum diameter of 103 mm. This type of rhizome-seed produced 300 g of rhizomes per plant in this scenario. This productivity was obtained in an area of academic experimentation. When arrowroot seedlings were granted to small organic farmers, about 80 km from the research site, it was possible to obtain a double production (600 g/plant) under the same conditions of rhizomeseed size and spacing arrangement. The result is still under analysis but the probability is that the plants were naturally (A)

(B)

Figure 5.7 (A) Rooted stem and (B) arrowroot rhizome with buds and roots. (From the authors.)

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mycorrhized (Coelho, 2003), since there is no use of chemical defenses in organic cultivation. The total production cost per hectare of arrowroot is US$673, due to the adaptation to the costs established for the cassava crop. Hence, taking these calculations into consideration, the production of rhizome-seeds would only be viable with values below US$2 (Guilherme et al., 2017). Considering the results obtained in these field surveys, it was possible to elaborate Table 5.2, which compares the two systems of planting described earlier, with rhizome-seeds and with rooted stems. As for the dry matter and starch contents, the mean values reported in the literature were 27.50% starch expressed in fresh mass and 27.50% in dry mass. The production of starch per hectare as displayed in Table 5.2 (1.87 tonnes/ha) is a lot smaller than that mentioned by Cereda (2001a), who found values of arrowroot starch produced by small Chinese farmers between 5.5 and 6.0 tonnes/ha, within data based on field verifications that can still be improved. The cultivation of arrowroot with rooted stems presents advantages in relation to the use of rhizome-seeds or their parts, thus deserving the attention of researchers. However, at the moment of harvest, the arrowroot plant is very dry, and no stems are available for the next cultivation cycle. Consequently, it will be necessary to carry out a specific planting to obtain at least 37,000 stems/ha. This can be evaluated considering the natural lateral shoots of the arrowroot of the variety Comum, which presents three or four stems per plant. The use of rooting regulators can be conducted to improve rooting.

5.5.2 Evidence of the Differentiated Quality of the Starch of Arrowroot (Maranta arundinacea L.) The production of nontraditional starches aims mainly at obtaining differentiated products, to be commercialized in a specific market, allowing then the rise of prices and decrease in

Planting with stem Number of pits per hectare (0.28 m2) Weight of rhizome-seeds in planting Expectation of production of rhizomes Harvesting rhizomes discounting the rhizome-seeds Production of dry mass per hectare (28.50%) Production of starch per hectare (27.50%) Loss of money by planting rhizomes Expected value of the external market starch at US$5/kg a

30 g
0.28 m2 35,715 1.01 tonnes/ha 7.80 tonnes/haa 6.79 tonnes/ha 1.94 tonnes/year 1.87 tonnes/year US$5.050/year US$10.200/year

1 stem/0.28 m2 35,715 Nothing 10.70 tonnes/ha 10.70 tonnes/ha 3.05 tonnes/year 2.94 tonnes/year Nothing US$16.050/year

Considering a survival rate of only 73% of the rhizome-seeds cultivated; the international value of the starch considered as US$5000/tonne. Adapted from Empresa Baiana de Desenvolvimento Agrícola, 2013. EBDA Busca resgatar cultura da araruta em Cruz das Almas. EBDA, Bahia; Source: From the authors.

Starch Valorization From Corm, Tuber, Rhizome, and Root Crops

Table 5.2 Projection of the results obtained by the cultivation of rhizome-seeds of 30 g and rooted stems, in a spacing arrangement of 0.8
0.35 m (0.28 m2), yielding 300 g of rhizome per plant with 71.5% humidity and 27.50% starch content expressed in fresh mass Options With rhizome With stem

199

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the dependence of the starch-producing companies on the same raw material. When these products are gluten free, they also provide an option for starches and cereal flours, which makes them recommended for people who have any kind of food intolerance (Cereda., 2002; Cereda and Vilpoux, 2003). The literature claims that the starch of arrowroot has special characteristics for fine confectionery, with applications in the European market (Mason, 2009; Cunha, 2016), presenting qualities considered unmatched and that confer lightness and high digestibility to all its derived products (Neves et al., 2005). According to Mason (2009), arrowroot starch is very special in Britain, chiefly because of its great digestibility. Its starch can be used in cooking, such as for making puddings by heating it in milk and blending with eight parts of wheat flour. There are also arrowroot biscuits, and the starch can also be used in jellies, cakes, and several infant food mixtures. However, sometimes the product labeled in the market as arrowroot starch may be in reality the starch obtained from cassava. Hence, if arrowroot starch is required in the production, its origin should be verified. The only problem is how to do so. The literature presents enough information to characterize arrowroot starch, but no hypothesis was found to explain its exceptional quality. In rhizome characterization and analysis of the starch of arrowroot (6.4), a diversity of results for the same analyses was highlighted by several authors, which presupposes the need for the standardization of methodologies, materials, and ways to express the results in a comparable manner. In summary, it is possible to say that arrowroot starch contains granules considered small, medium, and large (29.2e64.2 mm with an average size of 48.4 mm, length/grade of 1.20 with roundness 0.73, with amylose content of 24.8% and a gelatinization temperature of 74.8 C). It has a relatively high gelatinization temperature and resistance to mechanical shear. Therefore, it presents satisfactory texture for foods at high

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temperature or when processed as a stabilizing agent for infant food and products processed at ultrahigh temperature (Madineni et al., 2012). The main problem is, these characteristics are common to most starches extracted from underground organs. Although the literature shows results for arrowroot starch and even its comparison with other starch sources, there are always differences due to the inherent variability of plant sources. To overcome this problem and to be able to make these comparisons, unpublished data on different starch sources are presented in Table 5.3. For this, all analyses were carried out in the same laboratory, using the same methodology and equipment. Trying to answer the main question of the research, comparisons will be made between arrowroot starch and other tropical starches for each parameter. Table 5.3 presents, then, the parameters that may influence the starch quality. Table 5.3 shows that the apparent amylose content of arrowroot starch is intermediate, between those of Queensland arrowroot and cassava, but also that it is not as extreme as the largest (C. edulis) or the lowest, found in cassava starch. The phosphorus content, as well as the number of reducing ends measured by the carboxyl (COOH), cannot differentiate arrowroot starch from the other starches. Although the phosphorus content is high compared with the starch extracted from cassava roots and sweet potato tubers, it does not differ from the starch contents extracted from other rhizomes (C. edulis and Colocasia esculenta). There is little information on the influence and origin of carboxyl groups on native starches. The factors that could explain the carboxyl content are lipids, with their fatty acids, and proteins, both at very low levels in all the starches analyzed in this experiment. The highest levels observed in Queensland arrowroot rhizomes may be related to the phenolic content present in this plant. The third is the occurrence of the oxidation reaction, which characterizes the hypochlorite- or hydrogen peroxide-modified starches, a hypothesis also distant for native starches.

202

Arrowroot Sweet potato Queensland arrowroot Cassava Taro Source: From the authors.

20.34 17.80 29.99

0.32 0.23 0.39

0.076 0.100 0.121

21.37 12.63 42.84

28.56 14.97 52.9

450 128 1725

22.00 9.00

0.18 0.39

0.080 0.085

11.00 8.20

13.0 3.19

120 4

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Table 5.3 Comparison of characteristics that might interfere with arrowroot starch quality and other starch sources Size of granules Apparent (mm) amylose Phosphorus COOH Area Raw material (% p/p starch) (g/kg) (% p/p) Small Bigger (mm2)

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The average diameter of the starch granules, as generally reported in the literature, does not consider the normal variation in the samples and the distribution among the different sizes. The results of Table 5.3 represent the means of the largest and smallest granules, as well as the area provided by the set of granules. This parameter is uncommon in the literature, although it is possible to obtain it with the same methodology. Taro starch granules are considered the smallest among all the potential raw materials tested, whereas the Queensland arrowroot granules are considered one of the largest. This information is demonstrated and proven in Table 5.3. In the case of arrowroot starch, larger granules were not found, but the character that differentiates it from the others is the average area provided by the surface of its granules (450 mm2), which is smaller than only the surface area of Queensland arrowroot granules (Fig. 5.8). This aspect may be an important differential because it cannot be explained by the means of the diameters of the smaller and larger granules but may result from a higher percentage of large granules, which provide a larger surface area than smaller granules.

Figure 5.8 Appearance and variation of arrowroot starch granules size analyzed in a 10-fold increased optic. (From the authors.)

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The results of Table 5.3 show that the contents of apparent amylose and phosphorus and the starch granules’ size do not differentiate arrowroot starch relative to other native starches, other than the surface of the granules, so Table 5.4 analyzes their pasting properties. Results in Table 5.4 show that the peak and end viscosity does not differentiate arrowroot starch from the other tropical starches, as it does with the low values for yam and taro. The low value for breakdown (The value 71,9 was corrected for 140 RVA) and the value for breakdown that is higher than that obtained for Queensland arrowroot starch (158.1 RVA) are both unique to arrowroot starch and agree with the literature on viscosity reduction, following recovery. The same happens with the tendency for retrogradation, in which the value obtained for arrowroot starch approaches that obtained for cassava starch. Finally, the paste temperature and the time for peak viscosity presentation do not differentiate the arrowroot starch from the starch of Queensland arrowroot. According to Madineni et al. (2012), this characteristic would differentiate arrowroot starch as a special raw material for use in food. Although the viscosity is expressed in different units, in pastes at 5% of the starch content (dry basis), the authors observed that at 74.8 C the peak viscosity is 1494 cP and when cooled to 50 C it rises to 2007 cP of viscosity. The relatively high gelatinization temperature of the starch must be associated with its mechanical shear strength after gelatinization and resembles the modified starches of the stabilized type. Still, the same authors report good stability in the freezeethaw cycle, with 1.6% of syneresis, so a low tendency of retrogradation is compatible with that of the waxy maize. It is also observed that the paste’s clarity remains around 16 T% in the gels prepared at 1% starch content (dry basis), close to the values obtained by the other tubers, as is the amylose content (24.8%). The low tendency for retrogradation of arrowroot starch does not match the formation of a foam structure after its gel is

Peak

Breakdown

Starch

Peak

Fall

Arrowroot Sweet potato Cassava Queensland arrowroot Taro Yam

570 520 482 1150 250 330

RVA, rapid visco analyser. Source: From the authors.

Final

Setback

Break

End

Retrogradation

375 341 250 710

430 433 330 800

570 458 410 792

195 404 80 8

5.9 6.0 5.3 5.8

61 65 63 67

158 200

177 158

158 200

19 42

9.0 10.8

76 83

Time to peak(min)

Pasta temp.(8C)

Starch Valorization From Corm, Tuber, Rhizome, and Root Crops

Table 5.4 Pasting properties of native starches evaluated at 2.5% of the starch content (w/v) and their comparison with the starch of arrowroot (mean of duplicates) Viscosity (RVA Brabender unity)

205

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Starches for Food Application

frozen. The retrogradation allows the formation of the single and double helices, forming a crystalline network as a function of junction zones between the amylopectin and the amylose molecules (Eliasson, 1996), promoting the production of a liquid in the process called syneresis (Lajolo and Menezes, 2006). During the retrogradation process, a foam structure (Morris, 1990) is formed, especially in the slow freezing situation with the formation of ice crystals (Ferrero et al., 1993a,b). This characteristic not only was observed but also led to the deposit of a patent on the exploitation of this characteristic, which is more common in gels of cereal starches. Fig. 5.9 illustrates the foam structure of arrowroot starch at different concentrations in water compared with polyurethane foam used in hydroponic cultivation. In the sequence, the tendency for the formation of a foam structure was compared by means of correlation analysis with other characteristics of tropical starches. The results highlighted the concentration of phosphorus and carboxyl as percussive variables and favored the formation of this foam structure. These two characteristics differentiated arrowroot starch from other starches. The length of fraction III of the amylopectin side chains was also identified as one of the factors favoring the formation of the foam structure of the gels both under freezing and under refrigeration only.

Figure 5.9 Supports for commercial hydroponic cultivation made with polyurethane foam, compared with the same support made with 15% (B.15%), 20% (B.20%), and 25% (B.25%) arrowroot starch in water, followed by cooking and freezing. EF, polyurethane foam; B.15%, B.20%, and B.25%, percentage of arrowroot starch in water suspension. (From the authors.)

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Table 5.5 shows the size and percentage of the arrowroot amylopectin side-chain fractions, compared with the same fraction in native cassava, sweet potato, taro, and yam starches. Table 5.5 shows that the size and frequency of the amylopectin fractions do not differentiate the arrowroot starch. However, among the values obtained for the other starches, the one for arrowroot presented the smallest size for fraction II and was among the smaller ones in fraction III. In relation to the frequency they are identified, the arrowroot starch profile is one of those in which fractions I and II were less frequent, but with fraction III among the most frequent. Even though it was not possible to explain the differential quality of arrowroot starch through the characteristics of its starch, the comparison showed some points that would be worth a further investigation. This is an important point because it would make it easier to commercialize the starch at higher prices. Still, the demand for the market requires constant production, with the product at table quality. Manual extraction cannot maintain a stable starch quality, but on the other hand, the smallest commercial units in Latin America process around 400e600 tonnes of raw material in a working day of 8 h. Therefore, while it is not possible to increase the scale of production in the field or to prove that its starch differs from other starch commodities, another possibility to take advantage of the potential of the plant and to valorize its product is the development smaller equipment within the concept of appropriate technology (Schumacher, 1973). This concept was used when the extraction of cassava starch was realized to produce fermented cassava starch in Brazil and Paraguay (Westby and Cereda, 1994) and in the Cauca Valley, Colombia (Rodriguez, 2003; Wheatley et al., 1997). The development of mediumscale starch extraction equipment, while maintaining a stable quality, could allow the survival of small producers, not only in Brazil but throughout South America.

208

Starches

Arrowroot Cassava Sweet potato Taro Queensland arrowroot Yam DP: Degree of polarization Source: From the authors.

II

29 37 32 30 34 32

III

15 15 16 16 19 14

Fraction I

5 6 8 3 7 8

Fraction II

17 26 16 11 16 18

Fraction III

78 68 76 86 77 74

Starches for Food Application

Table 5.5 Size and percentage of the amylopectin side-chain fractions in the native starches evaluated, in comparison with the starch of arrowroot Size (DP) of fraction % of the fraction

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209

The use of small equipment boosted the production of fermented cassava starch because the small-scale producers were able to extract cassava starch and conduct the fermentation process. The modified starch derived displays a higher price than native cassava starch because it presents expansion properties without chemical or biological baking powder (yeasts) (Cereda and Brito, 2017). This type of starch is popular among almost all the South American countries and its price reflects the more accurate preparation methods in small processors. Precisely, this crescent and more rigorous consumer pressed the larger cassava starch extraction companies to become interested in the natural modified starch called fermented starch. To meet this new consumer Initially, they sold native cassava starch to producers of fermented cassava starch and then, started to produce and sell the modified product themselves. The lack of specific machinery that facilitates processing and commercialization (Silveira et al., 2013) is the last point to be addressed in this chapter.

5.6 ARROWROOT EXTRACTION USING SMALLSCALE EQUIPMENT The arrangement of operation units for the extraction of starch from rhizomes is peeling, washing, disintegration, extraction, purification, and drying (Cereda, 2002; Leonel and Cereda, 2002). According to Cereda (2002), most of the alternative starches follow the same sequence used in the commercial extraction of cassava starch. In Brazil, tests performed in this type of industry with an installed capacity of 400 tonnes of raw material per day using sweet potatoes and arrowroot presented satisfactory results both in extraction and in quality (Leonel et al., 1998). Although not widely reported, there are several literature reports on the design of medium and small equipment for the extraction of starch. Sheriff and Balagopalan (1999) developed a

210

Starches for Food Application

multiuse grater for starch extraction, with a capacity of 75e125 kg raw material per hour and evaluated the performance of the machine on different tuber crops. Sajeev and Balagopalan (2005) studied a starch extraction grater for yam, cassava, and potato. The capacity of the machine ranged from 120 to 200 kg raw material per hour, depending on the crop. In small applications, it is possible to choose between several types of equipment but the choice should consider the most suitable options to make the process less painful to the operators, preferably with cheap and easy maintenance at their own workplace. This technology is called appropriate or soft technology and, in general, the steps of grating, sieving, decanting, and drying of the starch are the most selected. For raw materials with a high moisture content, such as rhizomes, roots, corms, and tubers, the most important disintegration operation used is the grating/grinding (Sajeev et al., 2012), which destroys the plant cell walls and exposes the starch granules inside them (Leonel and Cereda, 2002). This proposal was adopted among the researchers who participated in a multidisciplinary project to propose and test a set of three machines that can work in series to extract starch from arrowroot (Fig. 5.10). The set consists of an adapted hammer mill, a rotating sieve, and a drier. The twist above the shaft promotes the movement of the disintegrated mass in the interior with consequent continuous separation of the starch suspension into water, which passes through the screens of the sieve and is collected in the collection chute, while the residual fibrous material is retained inside the sieve and moves along the central shaft and leaves from the opposite end. The set has the capacity to process up to 1500 kg of arrowroot per day, which corresponds to 350 kg of starch at 14% moisture content per day. This set of equipment was rated at a price of US$500 and presents the possibility of being used for the extraction of other types of starches (Branco, 2017).

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Arrowroot contains about 1.5% crude fiber, close to that of cassava (2.0%) and sweet potato (1.4%). This characteristic is a very important factor in the process of starch extraction. The processing of raw materials with higher fiber content requires adjustments in milling and extraction, stages in which the cells are broken up for the release of the granules and the washing of the material. If the bagasse is used as a source of dietary fiber, it could greatly contribute to the viability of processing, since it would generate other revenue for the industry (Leonel et al., 2005). Characterization results of this fiber highlighted the high level of phenolics, which nutritionally differentiates this by-product from the extraction of arrowroot starch.

5.7 THE FUTURE: FINAL CONSIDERATIONS The considerations resulting from the efforts of a multidisciplinary team to boost or at least stabilize arrowroot (M. arundinacea L.) cultivation resulted in recommendations. Regarding the increase in production in the field, the authors highlight the following points: • Planting material remains the greatest difficulty found in increasing arrowroot production, whether on a small producer scale or in larger areas. • Efforts should be concentrated on making the production of seedlings from rooted stems practical. • The production of mycorrhized seedlings, which could double the productivity to more than 20 tonnes/ha, would be an easier solution to implement. In view of the quality of arrowroot starch, the authors highlight the following points: • The analysis of the pasting properties highlight the low values of drop and break viscosity, which were the only ones that were differential for arrowroot starch gel. They also emphasize the low setback tendency. These results agree

212

Starches for Food Application

Figure 5.10 Design of the complete equipment for extracting the starch from arrowroot. 1, Adapted hammer mill; 2, fresh pulp rail; 3, starch milk rail; 4, rotating screen; 5, bagasse rail. (From the authors.)

with laboratory evidence that the pasting properties would be intermediate between the starches obtained from corn and cassava, respectively; • Results for size and frequency of amylopectin fractions do not differentiate arrowroot starch. Its amylopectin sidechain size is characterized by being one of smaller ones in fraction II, and among the smallest ones in fraction III. In relation to the frequency in which they are identified, the profile is one of starches in which fractions I and II are the least frequent, with fraction III among the most frequent. • The relatively high area provided by the set of starch granules may be a factor to be investigated to explain arrowroot starch quality. • The percussive and favorable variables for the formation of a foam structure were the concentrations of phosphorus and carboxyl groups, two characteristics that differentiated the starch of arrowroot. The resistance to syneresis during

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freezing can be explained by the formation of this foam structure, which keeps the liquid trapped, but which in turn is not compatible with the low tendency for retrogradation, pointing out that another type of character not described in the literature may explain the quality of the arrowroot starch gel. Analysis conducted by the authors shows that the amylopectin side-chain length of the arrowroot starch (fraction III) also does not differentiate it from the other raw materials, other than cassava starch and taro, nor does it explain the strong tendency to form the foam structure in the gel under freezing. In general, the authors highlight the following points: The fact that arrowroot starch is not sufficient in the market keeps the authentic arrowroot starch at good prices and favors fraud by the use of cheaper starches for its substitution, creating uncertainties in the market. This problem may be solved by increasing production in the field, but fraud may be suppressed using methods that allow the identification of added starches and thereby punishing inflators. It is necessary to act on the highlighted problems with the concept of multidisciplinarity. The mechanization of arrowroot cultivation and processing should be stimulated at the level of appropriate technology. High prices for arrowroot starch should be discouraged, since higher prices encourage the use of cassava starch or modified starches to compensate. Despite the challenge, scaling up and securing valorized markets may help stabilize arrowroot production.

ACKNOWLEDGMENTS We thank the EMBRAPA CENARGEN for kindly granting the varieties of Maranta arundinacea for the research conducted by the multidisciplinary researcher team. We are grateful to CAPES, for financial support in the form of resources and postgraduate scholarships from the years 2010e14

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(Process PNPD 2010, 2761/2010) and to CNPq, the National Council for Scientific and Technological, and to the Dom Bosco Catholic University for all scholarship granted. We thank Dr. Josimara Nolasco Rondon, for all the support in the obtainment of planting material from internodes and stems of arrowroot plants and Dr. Auricleia Sarmento de Paiva for collaboration with the field data release. We acknowledge Master Post-Graduate student Ingrid Batista Pinto and Nathalia Pereira Ribeiro and the following undergraduate students in the scientific initiation stage: Aline Abes, Jeniffer Narcisa de Oliveira, Jefferson Lucas Salvador da Silva, Filomena Maria Rosa Barbosa Lucas, and Guilherme A. Abrantes Sousa.

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FURTHER READING Cereda, M.P., 2003. Produção de fécula a partir do biri (Canna edulis). In: Vilpoux, O. (Ed.), Tecnologia, uso e potencialidades de tuberosas amiláceas latino-americanas, vol. 2. Fundação Cargill, São Paulo, pp. 191e199. Tester, R.F., Karkalas, J., Qi, X., 2004. Starch - composition, fine structure and architecture. Journal of Cereal Science 39, 151e165. https:// doi.org/10.1016/j.jcs.2003.12.001. Tester, R.F., Qi, X., Karkalas, J., 2006. Hydrolysis of native starches with amylases. Animal Feed Science and Technology 130 (1e2), 39e54. https://doi.org/10.1016/j.anifeedsci.2006.01.016.

CHAPTER 6

Physical Modifications of Starch Marcio Schmiele1, Ulliana Marques Sampaio2, Paula Thamara Goecking Gomes1, Maria Teresa Pedrosa Silva Clerici2 1

Federal University of Jequitinhonha and Mucuri Valleys, Institute of Science and Technology, Diamantina, Minas Gerais, Brazil; 2University of Campinas, School of Food Engineering, Campinas, São Paulo, Brazil

Contents 6.1 Introduction 6.2 Conventional Gelatinization Processes 6.2.1 Conventional Cooking 6.2.2 Cooking With the Limitation of Water 6.3 Microwave Cooking 6.4 HeateMoisture Treatment 6.5 Cold-Water Swelling 6.6 Annealing 6.7 High Hydrostatic Pressure 6.8 Milling 6.9 High-Speed Shear 6.10 Ultrasonic Modification 6.11 Cold Plasma 6.12 Other Physical Modification Methods 6.12.1 Radio Frequency 6.12.2 Pulsed Electric Fields 6.12.3 FreezeeThaw Process 6.12.4 g-Ray and Electron Beam Irradiation 6.12.5 Combination of Physical Methods 6.12.6 Production of Starch Nanoparticles 6.13 Future Perspectives References

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6.1 INTRODUCTION The use of starch in food products has increased, especially in the reformulated products, to improve the technological properties or allow the reduction or absence of some ingredients, since starch has little impact on flavor, color, odor, or texture of the product, and in addition presenting an important application as a body agent. Knowledge about new kinds of physically modified starch has met the demands of the new consumer, who looks for safe ingredients for consumption, obtained by environmentally friendly methods and that contribute to the trend of the clean label. Bemiller (1997) reported the reasons for increased investment in the development of physically modified starches. According to that author, few new chemical reagents or derivatives will be approved for use in chemical modification methods. In addition, the levels of chemical reagents in formulations should be reduced, for the protection of both consumers and the environment, safety at work, and savings in production costs. The main industrial reasons for modifying starches are based on their physicochemical properties and, from a nutritional point of view, the modifications have changed, since wellestablished processes for the production of rapidly digestible starches (RDSs) are giving rise to new methods of obtaining slowly digested starches (SDSs) and resistant starches (RSs). The main reasons for starch modification include the following: • Raw starch is insoluble in cold water and can decant if kept in tanks without constant stirring. In addition, suspensions with high starch concentrations function as a nonNewtonian fluid, presenting dilating properties, which makes it difficult to pump through the pipes. This behavior is explained by Royer et al. (2016), who showed that these

Physical Modifications of Starch

225

frictional contact forces and their hydrodynamic contributions fit accurately to the viscosity measured in a wide shear stress and particle size range. New uses for raw starch suspensions have been proposed, such as their use in bulletproof vests, due to the high capacity to absorb the impact energy and still be flexible during a movement like walking or running. • When heated, starchewater mixtures do not form perfect pastes, which have high viscosity and cohesiveness, and exhibit retrogradation and syneresis after cooling. In the case of freezeethaw (FT) cycles, there is a weakening of the spongelike paste. This chapter presents the methods of physical modification of starch, reporting on the conventional methods and pointing out new technologies, some still at experimental levels.

6.2 CONVENTIONAL GELATINIZATION PROCESSES Pregelatinized starches are cold-water soluble and have the ability to form a cold-water paste (Colonna et al., 1984), and can be used in several formulations for thickening or water retention without heating, including puddings, instant milk mixes, and breakfast foods, and as an extender in the meat industry and in fruit pie fillings, as they can increase the aroma retention (Powell, 1965). In food, starch must be gelatinized to be digested by the amylolytic enzymes of the human digestive system and make it a source of energy. It can be subjected to home cooking or industrial food processing for the preparation of starchy foods, which has led to an increase in formulations containing dry and precooked starches, aiming at rapid or instant preparation.

6.2.1 Conventional Cooking Conventional starch gelatinization methods are based on cooking under continuous stirring above the starch

226

Starches for Food Application

gelatinization temperature in a water:starch ratio of 3:1 or more for more than 20 min, since there will be an increase in the volume of the granule until breaking and exudation of the molecular components, which will affect the viscosity of the starch paste formed. Cooking temperature, water content, agitation, and cooking time can vary according to the concentration and source of starch, gelatinization temperature, stirring speed, water volume used, time, and evaluation methods, and whether the starch is pure, in the form of flour, or a formulated product. Several classic publications, such as Powell (1965), Leach (1965), and Greenwood (1976), have reported the characteristics of the process in more detail. The gelatinized starch may be used hot, after cooling, or after drying as a pregelatinized starch powder. In the industrial cooking process, heating equipment such as turbo-mixers, autoclaves, and heating tanks may be used, and the water removal can be performed using a spray-drier; by freeze-drying, drumdrying, or flash-drying; or using a drying oven, among other methods. The major challenges of these processes include high energy expenditure, time, temperature, degree of agitation, and control of the gelatinization and retrogradation of the starch paste. When starch is subjected to drying, the slurry of starch may exhibit a low solids content (Leach, 1965; Greenwood, 1976). The heat treatment of starch may be carried out for purposes other than gelatinization and changes in cold viscosity. Studies have focused on starch retrogradation and the increase in regions resistant to enzymatic digestion. Some studies include the following: • Many authors used high autoclaving temperature and long storing time, varying the cooling time and cooling cycles to obtain RS. The authors showed that the factors that most affected the production of RS by autoclaving were temperature, moisture, number of cooking/cooling cycles,

Physical Modifications of Starch

227

and type of starch (Sievert and Pomeranz, 1989, 1990; Mangala et al., 1999; Teixeira et al., 1998). • Tian et al. (2012) studied the dual-retrogradation treatment (gelatinizationeretrogradation and gelatinizatione retrogradation) for preparing SDS products from rice starch. The authors found 56% SDS in the 36-h interval between the gelatinization processes, which was higher than the starch obtained by single retrogradation, with 39.3% SDS. According to those authors, the dual-retrogradation treatment can increase the SDS yield, which is linearly related to the melting temperature range.

6.2.2 Cooking With the Limitation of Water The main processes for high manufacturing efficiency of gelatinized and dried starch include drying rollers and using atomizers or thermoplastic extrusion. Although drying rollers are simple and commonly used, they have high product cost, difficult operation, constant maintenance, and adjustment of the rolls (Greenwood, 1976), in addition to affecting the quality of the final product, which may be heterogeneous. The use of atomizers is economically limited, since cooked starch pastes have high viscosity, and the atomization systems operate at low solids contents (Chiang and Johnson, 1977). The most used process is thermoplastic extrusion, considered a versatile process, with high production capacity and adjustable for all starch sources. Historically, single-screw cooking extruders were developed in the 1940s to make puffed snacks from cereal flours or grits. An expanding demand for precooked cereals and starches required machines with larger capacity, so extruders with a nominal capacity of 5 tons per hour were developed in the 1960s, with numerous news applications: snacks, infant feeding, pet foods, etc. In the 1970s, products containing more than one component, such as egg rolls and ravioli, for coextrusion were developed. Then, the use of two extruders in series, the first for

228

Starches for Food Application

cooking and the second for forming and structuring, resulted in several products. At the end of the 1970s, the twin-screw extruders for food processing were adopted, expanding the range of application (Mercier et al., 1989). Thermoplastic extruders present temperature variations in the heating zones, and the single-screw type has a lower initial investment cost and maintenance compared with the twinscrew extruders (Serna-Saldivar, 2008). Regardless of the type of extruder, the equipment is basically composed of a preconditioning system, feeding system, screw or worm, barrel, die, and cutting mechanism. Inside the extruder, there are three different zones performing a series of specific functions, with different temperatures during the process: the first is responsible for mixing and transporting the raw material, the second confers high shear and cooking rate, and the third confers high pressure and has a higher temperature in relation to the other zones. The matrix at the end of the barrel provides back pressure and the mass expands to the final shape. Finally, the cutting system is located just after the die and cuts the material into pieces (El-Dash, 1981; Mercier et al., 1989; Riaz, 2000; Steel et al., 2012). During the thermoplastic extrusion, starch is converted into a viscoelastic fluid, which is forced out by the die, leading to a rapid expansion due to the difference in internal pressure between the equipment and the medium, with instantaneous water evaporation (El-Dash, 1981; Harper and Clark, 1979). The fluid must then undergo the drying and spraying process (Chiang and Johnson, 1977). This technology involves several variables; thus the changes in both the composition of the raw material and the process will directly influence the quality of the final product. Many studies on the extrusion process have used the response surface methodology to make changes in the process. As reported by Yacu (1990), several independent variables can affect the process, including the composition of the ingredients, particle size,

Physical Modifications of Starch

229

feeding, screw and die configuration, processing temperature, pressure, and residence time of the food in the extruder. The analyzed responses are called dependent variables and include the expansion, sensory characteristics, paste and thermal properties, water absorption index (WAI) and water solubility index (WSI) of the extruded starch, fiber content, and glycemic index, among others. Starch will be gelatinized during the extrusion process at high temperature and high pressure, with a moisture content of 15%e30%, which can also degrade to dextrinized starch. Thus, the WSI and the WAI will be indicative of the process conditions, since high temperature and pressure conditions and low moisture can lead to the formation of dextrinized starch, which increases WSI and reduces WAI (Mercier and Feillet, 1975; Yacu, 1990). The gelatinization mechanisms were studied by Gopalakrishna and Jaluria (1991) in simulation studies on a singlescrew extruder, and they found that the changes in moisture levels provide an estimate of the extent of cooking, owing to the moisture loss, in addition to the formation of starch hydrogen bonds with water. This phenomenon leads to the gelatinization and dextrinization of starch, initially by the decrease in free space along the thread of the extruder, leading to an increase in temperature and viscosity, thus promoting heating. The versatility of twin-screw extrusion cooking, which can operate in both low and high moisture and with various ranges of temperature, pressure, shear, and speed and numerous thread configurations, allows its use in the thermomechanical gelatinization and liquefaction of cereal starches and grains for the subsequent production of various starch-based syrups and ethanol (Linko, 1991). The simultaneous use of the extrusion process and a chemical reagent to obtain modified starch has been studied for more than 30 years, such as in the production of phosphate starch

230

Starches for Food Application

(Chang and Lii, 1992) and alcohol (Chang and El-Dash, 2003). These processes were advantageous because of the lower use of chemical reagents and the decrease in the volume of effluents, especially when the chemicals were safe. In addition, the reaction occurred in a short time, with processing at a lower moisture content and reduced drying time and temperature of the modified starch. The stability of modified starches in the extrusion process was studied by Jaekel et al. (2015). The authors used hydroxypropylated crosslinked starch to study the behavior of starch against thermoplastic extrusion. Traditionally, the crosslinked starch is obtained by presenting a greater resistance to the shear force under acidic conditions (low pH). The authors found a change in the technological properties of starch, resulting in a decrease in gelatinization temperature, peak viscosity, breakdown, setback, pasting temperature, and swelling power. In addition, an increase in the solubility of the extruded starch and the degree of gelatinization was observed. Schmiele et al. (2016) filed a patent using thermoplastic extrusion for the production of RS type V. RS V is usually obtained by the debranching of amylopectin with isoamylase and pullulanase and subsequent complexation with saturated fatty acids (Hasjim et al., 2010, 2013). However, biotechnological processes with the use of enzymes are still a costly technology. In this context, thermoplastic extrusion presents an advantageous technology to replace the use of enzymes, because of the higher shear rate during the process, leading to the dextrinization of starch, releasing linear molecules of lower molecular weight, which can complex with the fatty acids present in the sample. In addition, it is a process that does not present effluent generation (Steel et al., 2012). Masatcioglu et al. (2017) studied the effect of thermoplastic extrusion on the production of RS type III using high amylose maize starch as the raw material and the corotational twin-screw extruder. The authors concluded that the moisture

Physical Modifications of Starch

231

conditioning at 60% combined with two extrusion cycles at 60e140
C along the heating zones resulted in a 10% increase in RS, and the high amylose starch presented 44% of resistant starch. Table 6.1 shows the isolated or combined use of starch, the use of reagents, and the new tendency to produce RSs by thermoplastic extrusion.

6.3 MICROWAVE COOKING The use of microwave cooking has increased in foods with a variety of purposes, including drying, enzymatic inactivation, moisture control in cookies, and pregelatinization of starch, because of its rapid cooking (Chang et al., 2010). The authors reported several studies showing that the gels formed by heating starch slurries by using microwave energy had significantly different properties compared with those heated by using conduction heat. The lack of granule swelling and the resulting soft gel are two key observations that highlight the differences in the two modes of heating. The significant differences in the other molecular properties, including enzyme susceptibility and amylopectin recrystallization, suggest a different mechanism of gelatinization during microwave heating. Palav and Seetharaman (2007) studied maize starch subjected to microwave heating and thermal conduction, with variations in moisture. The authors found differences in pasting properties, texture, and enzyme susceptibility, and explained that gelatinization differs from the conventional method, since during microwave heating the starch granules lose their birefringence much earlier than the gelatinization temperature, due to the vibrational motion of the polar water molecules, with fast granule rupture and formation of film polymers coating the granule surface. This event results in a soft gel even in the absence of a continuous network of amylose chains.

Corotating twin screw

130/20 and 50

Sago and tapioca starch Potato starch

Single screw Single screw

160/20, 30, and 40 120/20

High-amylose and normal maize flour

Corotating twin screw

150/19

Cassava starch

Single screw

70e130/18e26

Decrease in peak viscosity, water absorption, and RS content and increase in water solubility index and antioxidant capacity Good floatability for mahseer aquafeed Increase in hardness without affecting expansion index for fish aquafeed Extruded high-amylose starch showed lower hydrolysis extent and slower hydrolysis rate than normal maize flour Intense pregelatinization of hydroxypropylated crosslinked cassava starch, reducing peak viscosity and increasing the degree of gelatinization

Sarawong et al. (2014)

Umar et al. (2013) RodriguezMiranda et al. (2012) Zhang et al. (2016) Jaekel et al. (2015)

Starches for Food Application

Green banana flour

232

Table 6.1 Physical modification by extrusion of starches and application to foods and feedstuff Die temperature Type of (8C)/moisture Raw material extruder conditioning (%) Main results References

Pea and lentil starches

Corotating twin screw

90/35

Starches isolated from unripe banana (Musa paradisiaca L.) and mango (Mangifera indica L.)

Single screw

90e150/15e40

Modified starch applied in noodles, promotes firmer and less sticky and less bright in color end product The RS formation in the extruder for banana starch was affected positively by temperature and inversely by moisture; moisture did not affect significantly RS formation in mango starch

Wang et al. (2014) Bello-Pérez et al. (2006)

RS, resistant starch.

Physical Modifications of Starch

233

234

Starches for Food Application

The use of microwave energy to obtain starches modified by annealing (ANN) and heatemoisture treatment (HMT) has been studied (Gupta and Kumar, 2003) and it can also be used to produce chemically modified starches (Shogren and Biswas, 2006), with energy savings, shorter time, and reduced use of solvents and reagents. Gonçalves et al. (2009) evaluated the effect of heat treatment at low moisture (25%e35%) in sweet potato root starch using a conventional oven (90
C/16 h) and microwave oven (35e90
C/1 h). The conventional oven modified the starch properties, increasing the amylose content, with further reduction of the granule expansion factor and more pronounced modifications in the viscosity profiles and pasting properties compared with the microwave oven treatment. In Chapter 7, Kong presents more details on the use of the microwave with a greater diversity of applications.

6.4 HEATeMOISTURE TREATMENT Modified starch can be obtained by HMT processing at temperatures above the glass transition temperature (80e140
C) of starch, combining low moisture (10%e35%) and different periods of time (from 15 min to 16 h) (Biliaderis, 2009). The HMT process presents varying results according to the process variables and the starch source, for example: • The lower the moisture used, the greater the changes in the surface of the starch granule, which may result in increased susceptibility to new chemical, physical, or enzymatic modifications (Gunaratne and Hoover, 2002). • Tuber and root starches are more sensitive to changes than cereal starches, as reported by Zavareze and Dias (2011) in a comparative study. Several authors (Gunaratne and Hoover, 2002; Vermeylen et al., 2006) reported that starch modification by HMT promoted changes in the crystallinity pattern of type B starches,

Physical Modifications of Starch

235

resulting in type A crystals (evaluated by X-ray diffraction), which was not observed for the other starches. As reported by Genkina et al. (2004), type B starches have a hexagonal thermodynamic structure with about 36 water molecules inside every cell, while type A has a monoclinic structure with about 6 water molecules inside the helices. Olayinka et al. (2008) reported that HMT starch gels showed a decrease in peak viscosity, breakdown, and setback compared with native starch gels. Zavareze and Dias (2011) summarized the starch modifications by HMT, including the reduction of swelling and solubility and the production of gels with less firmness and greater opacity, probably due to the reorganization of the crystalline structure of the starch granule, the interaction between the amylose and the amylopectin chains through hydrogen bonds in synergism with other bonds, and the amyloseelipid interactions. HMT starch has been widely used for infant foods and food products subjected to FT cycles (Collado and Corke, 1999).

6.5 COLD-WATER SWELLING According to Bemiller and Huber (2015), starch modification by cold-water swelling (CWS) can be carried out using three main methods: (1) process 1, in which corn starch is heated in 75%e90% ethanol to 150e175
C (300e345
F) for 0.5e2.0 h; (2) process 2, in which a starch slurry is very quickly heated in a special spray-drying nozzle and the droplets containing gelatinized granules are dried in a spray-drier; and (3) process 3, in which a starch is treated with an alkaline, aqueous alcohol solution at 25e35
C, as reported by Eastman and Moore (1984), Pitchon et al. (1991), and Jane and Seib (1991). The initial CWS starch modification methods reported by Chiu and Solarek (2009) and Singh and Singh (2003) were as follows: • Starch was placed in a mixture of water and an organic solvent, generally ethyl alcohol, in a proportion of 70%e80%, and heated in the range of 157e177
C for 2e5 min (Chiu and Solarek, 2009).

236

Starches for Food Application

• Starch was kept at room temperature in an alkaline alcohol solution (water, alcohol, strong base). The alkaline solution may be composed of sodium hydroxide or potassium hydroxide at a concentration of about 2e3 mol/L (Singh and Singh, 2003). Methods that concurrently use thermal and chemical gelatinization may be considered as mixed methods. Both methods for obtaining the modified starch require treatments above the atmospheric pressure. In view of this, a method was created at atmospheric pressure, wherein the starch granules are dispersed in water solution with polyhydric alcohol and heated in the range of 145e155
C for about 15 min, which causes rearrangement of the granule structure, providing a cold solubility of 70%e95% (Chiu and Solarek, 2009). The final properties of the modified starch depend on several factors, including the plant source, the alcohol concentration, the pH, and the reaction time. The starch modification is obtained by decreasing the dielectric constant of the medium, promoting the rupture of the crystalline structure of the starch, without disintegration of the starch granules. Thus, the starch suspension will exhibit substantial changes in physicochemical, morphological, thermal, and rheological properties, including an increase in hot viscosity and in cold viscosity, higher processing tolerance, and smoother-textured gels. In contrast, there is a decrease in amylose content. In addition, the modified starch granules have indentations and cracks, with changes in the granule morphology (Singh and Singh, 2003). The starch modified by CWS has several advantages, including the dispersion in hot or cold water without formation of agglomerates, since it should have a cold viscosity, with the capacity to absorb water and gel at room temperature. It presents instant dispersion, heat tolerance, rapid development of viscosity, and smooth and short texture, and is used in foods of fast preparation.

Physical Modifications of Starch

237

6.6 ANNEALING ANN is a physical reorganization of starch granules, which promotes both an increase in the gelatinization temperature and enthalpy and a decrease in the temperature range at which this endothermic phenomenon occurs. The heat required for gelatinization of starch is inversely proportional to the area of the starch crystalline region; thus, it is a technique with greater viability for starches with larger amorphous regions. The modified starch can exhibit a decrease in swelling power and solubility (Tester and Debon, 2000; Biliaderis, 2009). For ANN, it is necessary to heat the starch at a temperature higher than the glass transition temperature and lower than the gelatinization temperature, that is, in the range of 40e55
C, in the presence of moisture (about four times the starch weight of water) for 12 h or more. During the process, there is a reorganization of the semicrystalline structure of the starch, resulting in greater stability of the granules as a function of the lower free energy on the molecule and the interactions between the starch chains (Biliaderis, 2009; Zavareze and Dias, 2011). Tester et al. (2000) found that ANN can occur at up to 15
C below the gelatinization temperature, but the closer the gelatinization temperature, the more efficient the process. The higher interactions between the starch chains and the changes in the granule surface have been studied in relation to the digestibility of modified starches, as well as the formation of starches resistant to enzymatic digestion. After ANN, starch presents greater resistance to digestibility as a result of the rearrangement of its crystalline structure, presenting higher levels of SDS and RS, and lower levels of RDS (Chung et al., 2009; Zavareze and Dias, 2011). Many authors, such as Lee and Osman (1991), Gomes et al. (2005), Liu et al. (2009), and Chiu and Solarek (2009), believe in a partial ANN during the milling and extraction of starch (e.g., obtaining maize starch) in an aqueous medium. Once a

238

Starches for Food Application

slurry is formed in water with subsequent removal of the liquid phase, amylose can be leached, thereby altering the starch composition. Table 6.2 shows a summary of studies on ANN and HMT modifications with different applications and changes in the technological characteristics.

6.7 HIGH HYDROSTATIC PRESSURE High hydrostatic pressure (HHP) has been used to promote changes in amylaceous sources through a combination of high pressures, dwell time, the botanical source of starch, crystallinity, and solids ratio (Kawai et al., 2007). Water enters the starch granule as a function of the high pressure (100e1000 MPa), promoting the partial or total loss of birefringence, changing the granule shape and size, as reported by Leite et al. (2017) for pea starch. The process promotes starch gelatinization, with low granule swelling, low viscosity, and alterations in its physicochemical structure, such as the breaking of noncovalent bonds, mainly hydrogen bonds, which is responsible for the stabilization of the starch structure. Pea starch presents type C polymorphism, characterized by the overlap of types A and B polymorphisms; thus, greater changes are observed in the morphological structures and physicochemical characteristics due to the lower stability of B-type starch to the processing conditions (Pei-Ling et al., 2010). For processing, the product is vacuum packed together with a determined amount of water or a mixture of water and alcohol and inserted into a cylindrical steel vessel, and pressure is generated indirectly, varying from 400 to 700 MPa, with temperatures between 20 and 80
C (Norton and Sun, 2008; Yang et al., 2017). Table 6.3 shows many applications of HHP for different starch sources.

Table 6.2 Physical modification using annealing or heatemoisture treatment of starches Method (solids Type of concentration; Starch modification temperature; time) Results

ANN

20%, w/v; 30e50
C; 24 h

Buckwheat

ANN

25%, w/v; 50
C; 24 h

Potato

HMT

76%e88%, w/w; 110
C; 1 h

Increase in gelatinization temperature for all starches Wheat starch treated at 50
C showed disruption of granule morphology Yam and potato starch showed higher peak viscosity Increase in amylose content, relative crystallinity, resistant starch content Decrease in smooth surfaces, in vitro hydrolysis peak viscosity, and retrogradation Polymorphic change in X-ray B-type pattern to a mixture of A þ B types or totally A type Higher moisture treatment results in increase in relative crystallinity and gelatinization temperature; decrease in swelling power

Wang et al. (2017)

Liu et al. (2015)

Bartz et al. (2017)

239

Continued

Physical Modifications of Starch

Potato, yam, and wheat

References

ANN

50%, w/v; 50
C; 1e24 h

Canna

ANN

10%, w/v; 50
C; 0e7 h

Acorn

HMT

80%, w/w; 110
C; 24 h

Wheat

ANN

10%e50%, w/v; 40 and 50
C; 0.5e48 h

Acorn

ANN

30%, w/v; 50
C; 20 h

Slight changes in crystal structure Higher action in the amorphous regions of starch granules due the mobility and flexibility Increase in resistant starch level Swelling of amorphous regions and less compact structure observed by smallangle X-ray scattering analysis Increase in starch solubility and gelatinization temperature Decrease in swelling power, amylose leaching, relative crystallinity, peak viscosity, and retrogradation Higher moisture and time and lower temperature resulted in increase in starch stability while in storage and decrease in retrogradation degree Increase in solubility and gelatinization temperature Decrease in relative crystallinity, swelling power, peak viscosity, and retrogradation

Zhu et al. (2018)

Lan et al. (2016) Molavi et al. (2018) Yu et al. (2016) Molavi et al. (2018)

Starches for Food Application

Pueraria lobata (Willd.) Ohwi

240

Table 6.2 Physical modification using annealing or heatemoisture treatment of starchesdcont'd Method (solids Type of concentration; Starch modification temperature; time) Results References

Buckwheat

HMT

65%e80%, w/w; 110
C; 16 h

Red adzuki bean

HMT

70%, w/w; 120
C; 4e12 h

Breadfruit

HMT

65%e85%, w/w; 120
C; 4 h

Liu et al. (2015)

Gong et al. (2017) Tan et al. (2017)

Physical Modifications of Starch

ANN, annealing; HMT, heatemoisture treatment.

Increase in amylose content, relative crystallinity, thermal stability, and pasting temperature Decrease in swelling power and solubility Granules with less smooth surfaces Increase in starch hydrolysis and gelatinization temperature Decrease in resistant starch content, peak viscosity, and retrogradation Change in X-ray pattern from B type to A type Increase in amylose content, thermal stability, and pasting temperatures Decrease in viscosities and relative crystallinity

241

242

Starches for Food Application

6.8 MILLING Milling can be used to alter the morphology, crystallinity, solubility, and swelling power of starch granules. Even though this process is classified as a nonthermal modification, the changes promoted in the starch are consequences of the mechanical and thermal energy generated during milling, with an increase in temperature at the points of impact (Bemiller and Huber, 2015), as the starch undergoes the actions of various forces such as compression, impact, shear, and attrition (Karkalas et al., 1992). The formation of damaged starch may be influenced by the following factors: • Time • Morrison and Tester (1994) found a loss of shorter-range crystalline order and double helix content in amylopectin in ball-milled wheat starches. • Tester (1997) reported that native and waxy rice starch presented a damage of 30.3% and 36.0%, respectively, after 10 min of milling, with a damage increase of 73.6% and 76.5% by increasing the process time to 90 min. An increase in damaged starch was also observed in native maize starches (from 14.9% to 68.1%), waxy maize starch (from 23.8% to 85.3%), potato starch (from 38.2% to 94.3%), and pea starch (from 13.0% to 71.7%) subjected to similar processing conditions. The increase in damaged starch increased solubility and swelling, depending on the starch origin and process conditions. • Chen et al. (2003) found that the ball milling time of rice starch causes the reduction and disappearance of birefringence, X-ray diffraction peaks, and the endothermic event characteristic of gelatinization. • Amylose-to-amylopectin ratio • Amylopectin is more susceptible to depolymerization than amylose (Bemiller and Huber, 2015). When

Table 6.3 Physical modification by high hydrostatic pressure of starches or starchy flours and application to foods and feedstuff HHP conditions (pressure, Starch Concentration temperature, time) Results References

30%e50%, w/w

300e600 MPa, 22e25
C, 30 min

Normal and waxy rice starch

25%, w/w

600 MPa, 30
C, 30 min

Waxy wheat starch

10%, w/v

300e600 MPa, 20
C, 30 min

Waxy, normal, and high-amylose corn

40%, w/w

100e600 MPa, 25e35
C, 30 min

Decrease in swelling power, gelatinization temperature, and enthalpy Increase in granule size Higher area of imperfect crystallites in relation to perfect crystallites and increase in slow digestibility Decrease in glucose release Increase in slow starch digestibility Decrease in relative crystallinity and peak viscosity Gradually decrease in gelatinization enthalpy with higher pressure levels With higher amylose content a lower lamella thickness and higher granule swelling was observed; crystallinity Xray pattern types B and V were more resistant to HHP treatment in relation

Pei-Ling et al. (2012) Tian et al. (2014) Hu et al. (2017)

Yang et al. (2016)

243

Continued

Physical Modifications of Starch

Waxy corn

25%, w/v

400 and 600 MPa, 21
C, 3 and 6 cycles of 10 min each 100e600 MPa, room temperature, 5 min

Quinoa

10%, w/v

Pea

4%, w/w

300e600 MPa, 25
C, 15 min

Mung bean

20%, w/w

120e600 MPa, 25
C, 30 min

Colussi et al. (2018) Li and Zhu (2018) Leite et al. (2017)

Jiang et al. (2015)

Starches for Food Application

Potato

to A type; changes in starch morphology and lamella and greater crystalline structures HHP associated with retrogradation provides a lower in vitro starch hydrolysis, slower glucose release, and lower glycemic index Increase in particle size Increase in swelling power and solubility at 55
C, but a decrease at 75
C for these parameters Total gelatinization at 600 MPa Cold gelatinization due the loss of birefringence Total gelatinization at 500 and 600 MPa Increase in retrogradation Increase in viscosity up to 480 MPa, followed a decrease in viscosity at

244

Table 6.3 Physical modification by high hydrostatic pressure of starches or starchy flours and application to foods and feedstuffdcont'd HHP conditions (pressure, Starch Concentration temperature, time) Results References

Sorghum

20%, w/v

120e600 MPa, room temperature, 20 min

Red adzuki bean

20%, w/w

150e600 MPa, 25
C, 15 min

Liu et al. (2016)

Li et al. (2015) Physical Modifications of Starch

245

HHP, high hydrostatic pressure.

600 MPa, forming a weak gel and a high correlation between shear stress and shear rate data Crystalline pattern changed from A to B type at 600 MPa, rough surface of granules Decrease in oil absorption capacity, swelling power, viscosity, relative crystallinity, rapid starch digestibility Increase in apparent amylose content, slow starch digestibility, and resistant starch levels Partial destruction of crystalline structure Increase in granule hydration At low pressure, the internal structure of starch granules was damaged first, and at higher pressures, the proportion of damaged starch decreased Damaged starch granules could form intragranulesdbonded forces under higher hydrostatic pressure level, complete gelatinization

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comparing maize waxy starch with native starch, the former presented a higher rate of damaged granules, with the rheological properties being more affected, including the reduction of the apparent viscosity (Han et al., 2002). • Water • The addition of water in the system may have a plasticizing effect, reducing the breakage of starch granules. Shi et al. (2015) evaluated the physicochemical changes of maize starch with the addition of water (20%e30%) in ball milling. The starch granules remained largely intact, with oval-shaped or flat patterns. However, the broken granules formed larger particles in the presence of water. With respect to the pasting properties, an increase in paste temperature was observed, with a reduction in viscosity peak. The increase in paste temperature, in this case, may be due to the higher consumption of heat energy to solubilize the amorphous region, delaying the swelling of the granules. • In relation to the quality of starch produced by milling, Han et al. (2002) found that although it was possible to obtain damaged starches with lower molar mass in relation to the control, these starches were heterogeneous in quality and the process time was up to 60 min, indicating an increase in energy expenditure during the process. • Dhital et al. (2011) studied commercial potato, maize, and two varieties of high-amylose corn starch subjected to cryo-milling, and aimed to clarify whether the starch modification by milling can be considered mixed (thermal and physical) and whether the simultaneous action of heat and mechanical work can change the physicochemical properties of the damaged starch. The authors verified that the modified starch presented similar behaviors in relation to digestibility and other functional properties

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of starch subjected to ball milling (Morrison et al., 1994), suggesting that changes in the properties of ball-milled starch are predominately mechanically induced rather than thermal. Diop et al. (2012) studied the maize starch modifications by ball milling in ethanol medium. The authors observed that the increase in ethanol concentration increased the granule’s susceptibility to physical damage, due to the poor interaction between amylose and amylopectin chains. At low starch concentrations, the starch granules became more dispersed in the liquid, increasing the mobility in the system, allowing greater exposure of the particles during milling. In addition, ethanol can act as a damper, reducing the energy in the mill; however, at lower ethanol concentrations, the compacted sediment will reduce the process efficiency. Dai et al. (2018) studied the physical and chemical modification of starch by combining the use of sulfuric acid and milling to produce corn waxy starch nanoparticles, and found a 19.3% yield, according to the process variables.

6.9 HIGH-SPEED SHEAR Shahbazi et al. (2018) studied maize starch dispersions physically modified through a high-speed shear homogenizer with various shear-induced rates (56/s (367 G-force), 210/s (5690 G-force) and 400/s (20664G-force), respectively). The shear treatment produced a hydrogel with improved texture parameters and softer structure, and films with higher water resistance, tensile strength, and water barrier properties compared with the native starch.

6.10 ULTRASONIC MODIFICATION The ultrasound (US) technique in food technology is considered environmentally friendly and may be an alternative to

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various conventional processes, such as extraction, filtration, cooking, and depolymerization of polymers, such as starch. Its advantages include productivity and good yield, in addition to reducing the use of chemical reagents and heat, with shorter process time (Chemat et al., 2011), improving the quality of the products and reducing pathogens (Patist and Bates, 2008). US consists of mechanical waves of high frequency (>20 kHz) that have the ability to traverse the medium (air, liquid, or solid), propagating in sinusoidal waves. The sound waves propagating in the medium will generate a vibration, which will lead to the displacement of the particles, where an increase in pressure resulted in a decrease in density. Therefore, mechanical energy is the only type of energy imparted into the medium. The changes in the chemical and physical properties of the material are due to the cavitation phenomenon, which is dependent on the process parameters, such as frequency and power (Mcclements, 1995; Bermúdez-Aguirre et al., 2011). The US technique can be classified according to frequency and power as (1) high-intensity US / processed at low frequency (20e100 kHz) and high power (>10 W/cm2) and (2) low-intensityehigh-frequency US / processed at high frequency (20e200 MHz) and low power (