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Whole grains: processing, product development, and nutritional aspects
 9780815382423, 0815382421

Table of contents :
Content: Wheat. Rice. Barley. Oats. Rye. Maize. Sorghum. Millet. Buckwheat. Quinoa. Amaranth. Trends in whole grain processing technology and product development. Food safety management of whole grains.

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Whole Grains

Whole Grains

Processing, Product Development, and Nutritional Aspects

Edited by

Shabir Ahmad Mir Annamalai Manickavasagan Manzoor Ahmad Shah

CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2019 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed on acid-free paper International Standard Book Number-13: 978-0-8153-8242-3 (Hardback) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www. copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com

Contents Preface .......................................................................................................................vii About the Editors ........................................................................................................ix Contributors ................................................................................................................xi 1. Amaranth ............................................................................................................ 1 Cuauhtémoc Reyes-Moreno, Edith-Oliva Cuevas-Rodríguez, and Perla-Citlali Reyes-Fernández 2. Barley ................................................................................................................. 25 Paras Sharma and T. Longvah 3. Brown Rice ........................................................................................................ 49 Shabir Ahmad Mir, Annamalai Manickavasagan, Sowriappan John Don Bosco, and Manzoor Ahmad Shah 4. Buckwheat ......................................................................................................... 71 S.S. Arya and Kakoli Pegu 5. Maize ................................................................................................................. 87 Saraid Mora Rochín, Ada Keila Milán Noris, and Jorge Milán Carrillo 6. Millets .............................................................................................................. 103 Sudha Rani Ramakrishnan, Kavitha Ravichandran, and Usha Antony 7. Oats .................................................................................................................. 129 Gabriela Y. Campos Espinosa, Mallory E. Walters, and Apollinaire Tsopmo 8. Quinoa ............................................................................................................. 151 S.S. Arya and Kakoli Pegu 9. Rye ................................................................................................................... 173 C.W. Wrigley 10. Sorghum .......................................................................................................... 197 B. Dayakar Rao, Sudha Devi, E. Kiranmai, and Vilas A. Tonapi 11. Wheat............................................................................................................... 235 Aashitosh A. Inamdar and Suresh D. Sakhare

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12. Trends in Whole Grain Processing Technology and Product Development .................................................................................................... 257 Ting Liu and Gary G. Hou 13. Food Safety Management of Whole Grains ................................................. 281 Marco Spaggiari, Chiara Dall’Asta, and Gianni Galaverna Index ........................................................................................................................ 299

Preface Whole grains or whole grain products should contain all the essential parts and naturally occurring nutrients of the entire grain seed in their original proportions. If the grain has been processed, such as by being ground, cracked, rolled, extruded, or cooked, the food product should contain the same relative proportions of principal anatomical components (endosperm, germ, and bran) that are found in the intact caryopsis. Compared to whole grains, refined grains do not contain all the components in the same proportion as that in the intact grains and are naturally less nutritious due to the loss of bran and germ during milling/processing. Consumers cannot enjoy the health benefits of whole grains unless they have been processed to be edible. Whole grain processing includes removing the unwanted materials and hulling to remove the inedible husk. Whole grains contain higher phytonutrient contents than their refined counterparts. Whole grains are a rich source of minerals, vitamins, dietary fiber, lignins, β-glucan, inulin, phytochemicals, phytin, and phytostereols. The bran is the multilayered outer skin of the grain that protects the germ and the endosperm from damage from sources such as disease, pests, sunlight, and water. The bran is a potent source of phytochemicals, minerals, vitamins, and fiber. Whole grains have received considerable attention due to the presence of nutrients and phytochemicals in the bran layer. Whole grains play an important role in healthy diets, due to their potential role in minimizing the risk factors for several diseases. Numerous epidemiological studies have shown the protective role of whole grain foods against chronic diseases, such as cardiovascular disease, type 2 diabetes, and colon cancer. The strong evidence shows that foods rich in whole grains have health-protective effects, and stimulated interest in developing new technologies to improve the nutrition profiles of cereal foods. Whole grain products have a good potential for consumer acceptance and are regarded as health-promoting functional foods. Nowadays, with the increasing consumer desire for health-promoting foods, whole grain products are emerging in the market. Huge numbers of whole grain products are available in the market globally, including bread, noodles, pasta, brown rice, oats, barley, multigrain products, and so on. Because different whole grains have different compositions and health benefits, technologies have been developed to allow the use of versatile grain raw materials to manufacture vast varieties of multigrain products and develop new product concepts. This book is the first of its kind focusing on the whole grain processing of individual grains. Each chapter discusses the processing, product developments, and nutritional aspects of individual grains, including amaranth, barley, brown rice, buckwheat, maize, millets, oats, quinoa, rye, sorghum, and wheat. In addition to this, current trends in processing technology and product development for whole grains are explained in detail in a separate chapter. The last chapter deals with the food safety management of whole grains. Contributions from experts in the field make this a key reference material for all aspects of research of whole grains. We believe this comprehensive collection will benefit students, scientists, and professionals in the area of whole grains. vii

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We are thankful to all the contributors for their cooperation and promptly submitting their chapters. We also express our special thanks to Stephen Zollo, senior editor at CRC Press, for his encouragement, support, and advice. The unending support provided by the staff of the editorial and production departments of CRC Press/ Taylor & Francis Group to bring about this book in its present form is whole heartedly acknowledged.

About the Editors

Shabir Ahmad Mir, PhD, obtained his PhD in food technology from Pondicherry University, Puducherry, India. At present, he is an assistant professor at the Government College for Women, Srinagar, India. He has received the Best Whole Grain PhD Thesis Award 2016 (South Asia) for outstanding research work by the Whole Grain Research Foundation. Dr. Mir has published numerous international papers, book chapters, and has edited two books. In addition to the close association with many scientific organizations in the area of food technology, he is an active reviewer for the journals Food Chemistry, Journal of Cereal Science, Journal of Food Science and Technology, Food Packaging and Shelf Life, and many other scientific journals of repute. Annamalai Manickavasagan, PhD, PEng, obtained his PhD in biosystems engineering from the University of Manitoba, Canada. At present, he is an associate professor at the University of Guelph, Canada. He has published more than 50 scientific papers in peer-reviewed journals and has edited five books. He has supervised more than 10 postgraduate students (MSc and PhD). He is the founder and president of the Whole Grains Research Foundation in India. Through this foundation, he promotes whole grains research in Asia. He has organized several conferences, symposiums, and workshops on whole grains. Manzoor Ahmad Shah, PhD, received his MSc (food technology) degree from Islamic University of Science & Technology, Awantipora, India, and his PhD (food technology) from Pondicherry University, Puducherry, India. At present, he is an assistant professor at the Government College for Women, Gandhi Nagar, Jammu, India. The author has been awarded with the gold medal for outstanding performance during his MSc degree program. Dr. Shah has more than 30 publications in internationally reputed journals and 15 book chapters. He is an active reviewer for the journals LWT – Food Science & Technology, Food Packaging and Shelf Life, Food Research International, and many other scientific journals of repute. He has attended several national and international conferences, workshops, and seminars.

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Contributors Usha Antony Centre for Food Technology Department of Biotechnology Anna University Chennai, India S.S. Arya Food Engineering and Technology Department Institute of Chemical Technology Mumbai, India Sowriappan John Don Bosco Department of Food Science and Technology Pondicherry University Puducherry, India Jorge Milán Carrillo Facultad de Ciencias Químico Biológicas Universidad Autónoma de Sinaloa Culiacán, México Edith-Oliva Cuevas-Rodríguez Facultad de Ciencias Químico Biológicas Universidad Autónoma de Sinaloa Culiacán, México Chiara Dall’Asta Department of Food and Drug University of Parma Parma, Italy Sudha Devi University of Agricultural Sciences Raichur, India Gabriela Y. Campos Espinosa Food Science and Nutrition Program Carleton University Ottawa, Ontario, Canada

Gianni Galaverna Department of Food and Drug University of Parma Parma, Italy Gary G. Hou SPC Group Seoul, Republic of Korea Aashitosh A. Inamdar Flour Milling, Baking and Confectionery Technology Department CSIR-Central Food Technological Research Institute Mysore, India E. Kiranmai ICAR-Indian Institute of Millets Research Hyderabad, India Ting Liu U.S. Wheat Associates/Beijing Office Beijing, China T. Longvah Food Chemistry Division ICMR-National Institute of Nutrition Hyderabad, India Annamalai Manickavasagan School of Engineering University of Guelph Guelph, Ontario, Canada Shabir Ahmad Mir Department of Food Science & Technology Government College for Women Srinagar, India xi

xii Ada Keila Milán Noris Facultad de Ciencias Químico Biológicas Universidad Autónoma de Sinaloa Culiacán, México Kakoli Pegu Food Engineering and Technology Department Institute of Chemical Technology Mumbai, India Sudha Rani Ramakrishnan Centre for Food Technology Department of Biotechnology Anna University Chennai, India B. Dayakar Rao ICAR-Indian Institute of Millets Research Hyderabad, India Kavitha Ravichandran Centre for Food Technology Department of Biotechnology Anna University Chennai, India Perla-Citlali Reyes-Fernández Facultad de Ciencias Químico Biológicas Universidad Autónoma de Sinaloa Culiacán, México Cuauhtémoc Reyes-Moreno Facultad de Ciencias Químico Biológicas Universidad Autónoma de Sinaloa Culiacán, México Saraid Mora Rochín Facultad de Ciencias Químico Biológicas Universidad Autónoma de Sinaloa Culiacán, México

Contributors Suresh D. Sakhare Flour Milling, Baking and Confectionery Technology Department CSIR-Central Food Technological Research Institute Mysore, India Manzoor Ahmad Shah Department of Food Science & Technology Government College for Women, Gandhi Nagar Jammu, India Paras Sharma Food Chemistry Division ICMR-National Institute of Nutrition Hyderabad, India Marco Spaggiari Department of Food and Drug University of Parma Parma, Italy Vilas A. Tonapi Indian Institute of Millets Research Hyderabad, India Apollinaire Tsopmo Food Science and Nutrition Program Institute of Biochemistry Carleton University Ottawa, Ontario, Canada Mallory E. Walters Food Science and Nutrition Program Carleton University Ottawa, Ontario, Canada C.W. Wrigley QAAFI University of Queensland Brisbane, Queensland, Australia

1 Amaranth Cuauhtémoc Reyes-Moreno, Edith-Oliva Cuevas-Rodríguez, and Perla-Citlali Reyes-Fernández CONTENTS 1.1 1.2

Introduction......................................................................................................... 2 General Aspects of Amaranth ............................................................................ 2 1.2.1 Cultivar Characteristics and Main Amaranth Varieties ......................... 2 1.3 Processing/Milling ............................................................................................. 3 1.3.1 Extrusion ................................................................................................. 3 1.3.2 Roasting................................................................................................... 5 1.3.3 Germination ............................................................................................ 6 1.3.4 Expansion or Popping ............................................................................. 7 1.3.5 Milling..................................................................................................... 7 1.4 Product Development and Potential Uses of Amaranth ..................................... 8 1.4.1 Biofortified Products ............................................................................... 8 1.4.2 Baked Goods ........................................................................................... 9 1.4.3 Gluten-Free Products .............................................................................. 9 1.4.4 Other Uses of Amaranth ....................................................................... 10 1.5 Nutritional Properties and Health Benefits of Amaranth ................................. 10 1.5.1 Macronutrients ...................................................................................... 10 1.5.1.1 Carbohydrates ......................................................................... 10 1.5.1.2 Lipids ...................................................................................... 11 1.5.1.3 Proteins ................................................................................... 12 1.5.2 Micronutrients ....................................................................................... 13 1.5.2.1 Vitamins and Minerals ........................................................... 13 1.5.3 Biocomponents ...................................................................................... 13 1.5.3.1 Phenolic Compounds .............................................................. 13 1.6 Nutraceutical Properties and Potential Health Benefits of Amaranth ............. 14 1.6.1 Antioxidants and Free Radical-Related Diseases ................................. 14 1.6.2 Antihypertensive and Anti-inflammatory Properties ........................... 14 1.6.3 Cholesterol-Lowering Effect ................................................................. 15 1.6.4 Fiber and Glycemic Index Control—Diabetic Patients ........................ 15 1.7 Conclusion ........................................................................................................ 15 References .................................................................................................................. 16

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1.1 Introduction The amaranth plant (Amaranthus spp.) is a crop that originated on the North American continent (Das 2012). Despite that amaranth grains were consumed by ancient pre-Columbian cultures, it was only in recent decades that the cultivation and consumption of amaranth has spread worldwide because of its extraordinary nutritional quality, genetic diversity, and agronomic potential (i.e., phenotypic plasticity, tolerance of drought, and other stress factors) (Rastogi and Shukla 2013). Currently, amaranth is cultivated in many countries of North and South America, Asia, and Africa, with China, India, Kenya, Mexico, Nepal, Peru, the United States, and Russia being the most significant amaranth-producing countries (Santiago et al. 2014). From the biological point of view, amaranth grain shares characteristics of both cereal and legume seeds, because its protein content and amino acid composition is somewhere between cereal and a legume, and could be nutritionally considered as a natural mixture of rice and beans (Caselato-Sousa and Amaya-Farfán 2012). Amaranth has been recognized as an exceptional grain due to its nutraceutical properties. Amaranth is rich in low-glycemic index (IG  ≤  55) carbohydrates (i.e., starch and fiber), with an overall IG of 35, a desirable parameter for type 2 diabetic and cardiovascular disease patients (Schneider et al. 2015). Amaranth oil is also rich in unsaturated fatty acids (squalene, Ω 6 fatty acids) and has higher oxidation stability compared to other commercial oils (Gamel et al. 2007). Numerous reports have described the presence of high quality proteins in amaranth and the multiple health benefits and pharmaceutical potential attributed to bioactive peptides and protein hydrolysates from amaranth crops e.g., antitumor (Silva-Sánchez et al. 2008; Barrio and Añón 2010), anticarcinogenic (Maldonado-Cervantes et  al. 2010), and antihypertensive (Milán-Carrillo et  al. 2012; Montoya-Rodríguez et  al. 2015) properties. In addition, amaranth is also of nutritional interest due to its vitamins and minerals (Rybicka and Gliszczynska-Swiglo 2017; Temesgen and Bultosa 2017) and other bioactive compounds with known antioxidant properties such as polyphenols, flavonoids, tannins, and betacyanins, among others (de la Rosa et al. 2009; Vollmer et al. 2017). All the above mentioned nutritional qualities of amaranth make this crop very attractive for the food industry. There are many processing methods that could be applied to amaranth seeds to enhance one nutritional aspect over the other, depending on the consumer needs or the target population. In this chapter such methods will be discussed as well as the potential uses of amaranth in the development of new products.

1.2 General Aspects of Amaranth 1.2.1 Cultivar Characteristics and Main Amaranth Varieties Amaranth is a dicotyledon, fast-growing crop resistant to different climatic conditions such as cold and drought, and it can grow in saline, alkaline, and acid soils. This crop is also less susceptible to pests and microorganisms compared to rice, maize, and beans (Singhal and Kulkarni 1988; Yu et al. 2004). It has been reported that, in low water conditions, amaranth has a higher CO2 fixating efficiency and can produce large volumes of biomass (Paredes-Lopez et  al. 2006; García-Pereyra et  al. 2009).

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Apart from their color, one of the most apparent external aspects of the amaranth grains is their size. The grain of amaranth is among the smallest edible grains, which is a reason why its production is often limited, despite its important agronomic and nutritional characteristics (Bressani 1995). It is estimated that there are around 87 species in the Amaranthaceae family, the majority of which are wild. Some species are cosmopolitan, being both introduced and naturalized plants, with a weed-like behavior such as Amaranthus hybridus, Amaranthus retroflexus, and Amaranthus powellii. Vegetable amaranth has two major species Amaranthus tricolor and Amaranthus viridis (Rastogi and Shukla 2013). Finally, among the cultivated grain species are Amaranthus caudatus, Amaranthus cruentus, Amaranthus edulis, and Amaranthus hypochondriacus. The grain was greatly appreciated by the advanced Mesoamerican civilizations of the New World as a basic food in their diets. In fact, those species are presumed as good as cereal grains in term of nutritional and chemical composition (Akin-Idowu et al. 2016). Amaranth is grown in limited areas, but has good potential as a cash crop, either for local or export market. Grain is cultivated in some regions around the world (Angentina, Bolivia, Chile, Ecuador, Mexico, Haiti, Peru, and Uruguay); the yields obtained generally range between 203 and 7,208 kg per hectare. Research needs to be done on both the basic aspects of this cultivation and the development of farming technologies for the areas currently in production as well as the area of future expansion (semi-arid and arid zones). Furthermore, it is necessary to develop techniques and improved materials, as well as advertising campaigns recommending the product and its value as a food.

1.3 Processing/Milling Amaranth has attracted a great deal of interest in recent decades due to its valuable nutritional, functional, and agricultural characteristics. Amaranth seeds can be cooked, popped, roasted, extruded, and combined with other grains to develop products with good nutritional, sensorial, and nutraceutical characteristics. However, the processing of amaranth grains requires innovative approaches due to its small seed size. In this section the main methods for processing amaranth will be discussed. A summary of the main products obtained after amaranth processing are described in Figure 1.1.

1.3.1 Extrusion The extrusion technology is a continuous process that combines mechanical and thermal processes to obtain plasticized and restructured products with new shapes and textures. This process involves the use of high temperature for a short time in which moistened, expansive and carbohydrate or protein food materials are plasticized and cooked in a tube. The combination of moisture, pressure, temperature, residence time, and mechanical shear results in molecular transformations and chemical reactions that allow product expansion (Hauck and Huber 1989; Castells et  al. 2005; Singh et al. 2007). The materials subjected to extrusion undergo chemical, structural, and nutritional transformations. These transformations include partial denaturation of proteins, lipid oxidation, degradation of vitamins and phytochemicals, formation

Expansion/ popping

Gluten-free products

Flours and baked goods

Roasting

Fresh germination grains Snacks and Flours sweets

Germination

FIGURE 1.1 Commercial uses of amaranth grain after processing.

Snacks

Extrusion

Processing

Amaranth grains

Proteins

Wet milling

Flours

Fractions

Dry milling

Milling

Starch

Fiber

Ball milling

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of flavors, increased bioavailability of minerals and solubility of dietary fiber, and partial gelatinization of starch. The quality of the products obtained by this process depends on the operating conditions (Milán-Carrillo et al. 2002; Maskan and Altan 2011; Zhao et al. 2011). For instance, in extruded snack products of amaranth flours, in which the process of extrusion was optimized by modifying processing temperature and feed moisture, the maximum scores (most expanded and with the best texture) were obtained when the snacks were processed at 15% moisture and 150°C, indicating highly acceptable product (Chávez-Jáuregui et al. 2000). Similarly, Bressani (1990) found that amaranth-extruded products improved the nutritional value compared to the raw grain, and did not require a subsequent treatment for their consumption. It is possible to obtain extruded amaranth flours with a wide range of solubility, which makes them very versatile to use for beverage elaboration. During the extrusion process, amaranth (Amaranthus caudatus) decreased its content of phytic acid, total phenolic compounds, and antioxidant capacity while improved in vitro protein and starch digestibility, thus demonstrating the potential of this technology for nutritional applications (Repo-Carrasco-Valencia et al. 2009). The nutrient might be lost due to extrusion utilizes high pressure (HP) (200, 400, and 600  Mpa) to which amaranth proteins are very sensitive. They suffer a high degree of denaturation accompanied by a decrease in protein solubility and protein dissociation and aggregation. On the other hand, Montoya-Rodríguez et al. (2015) reported that extrusion process of amaranth grain had a greater impact on the peptide profile, producing more peptides with a lower molecular weight and with biological activity. Extruded amaranth flours are a source of peptides with potential biological activity (inhibitors of the angiotensinconverting enzyme [ACE] and dipeptidyl peptidase [DPP-IV]) related to the prevention of chronic degenerative diseases. Understanding the effect of HP on the structural properties of amaranth proteins and their consequences in their functionality may be useful to better utilize these proteins as food ingredients or in the formulations of novel foods (Condés et al. 2012). The extrusion conditions optimized for amaranth (extrusion temperature = 127°C/screw speed = 130 rpm) resulted in an increase of its antioxidant capacity versus raw grain (5,046 vs. 4,403  μmol Trolox equivalents (TE)/100 g sample, (dry weight DW) (Milán-Carrillo et al. 2012). This behavior could be attributed to: (1) the rupture of bound phytochemicals and release of free phytochemicals; (2) the inhibition of enzymatic reactions of oxidation; or (3) the darkening of the extruded amaranth flour indicating the formation of Maillard reaction products with antioxidant properties (Bressani 1990; Milán-Carrillo et al. 2012).

1.3.2 Roasting Roasting is a typical high-temperature, short-time process. It retains nutrients and inactivates growth inhibitors and microorganisms by reducing the water content of the products, thus prolonging their shelf life (Srivastav et al. 1990; Su et al. 2011). The conventional roasting process is performed in an oven, using conduction, convection, or radiation at temperatures from 150°C to 350°C for periods that vary from 5 to 75 min depending on the grain size (Jogihalli et al. 2017). The roasting process is used not only to improve the sensorial characteristics (i.e., color, flavor, and aroma) of the food, but also to increase protein digestibility and the content of phenolic compounds, and thus the antioxidant capacity of the grains. When amaranth is subjected to roasting, it changes its physical and chemical qualities. The heat applied during this

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process can alter the configuration of the proteins making them more digestible, thus inducing a desirable effect. However, considerable losses have been reported of some amino acids, as well as of antinutritional factors (Bressani 1995; Pizzani et al. 2006). The roasting process of amaranth also increases its antioxidant capacity compared to unprocessed grains (7,053 vs. 4,403 μmol TE/100 g sample, dry weight) when conditions for such processes are optimized for greater antioxidant activity (Milán-Carrillo et al. 2012).

1.3.3 Germination Germination consists in the resumption of the metabolic activity and the active growth of the tissues of the embryo, resulting in the rupture of the seed cover and the emergence of a seedling (De Ruiz and Bressani 1990). In sequential order, germination involves rehydration, the use of reserved substances (proteins, carbohydrates, and lipids), and the formation of new structures such as membranes and cell walls, in addition to the synthesis of amino acids, nucleotides, organic acids, and sugars, to generate new cells and tissues during growth allowing the seedling to assume an autotroph mode of existence. The advantages of this process are: (1) product generation at any time of the year; (2) little economic investment; (3) high performance; and (4) generation of products of high biological value and digestibility, among others (King 1991; Solano et al. 2000; Barrón-Yánez et al. 2009). Several reports indicate that the germination process generates great nutritional changes in the seeds, improves the quality of proteins, decreases the lipid content (by lipases activity presence) but transforms the lipids remaining in polyunsaturated fatty acids, increases the bioavailability of minerals and vitamins, as well as decreases antinutritional factors (phytates, trypsin inhibitors). Changes in the chemical composition and nutritional value that occur during this process depend on the species and germination conditions used. Variations in the methods and conditions used during this treatment include: grain variety, harvest time, type and proportion of disinfectant agents, soak time, use of elicitors, temperature, and germination time (Gajewski et al. 2008; Barrón-Yánez et al. 2009; Mendoza-Sánchez et al. 2016; Tyszka-Czochara et al. 2016; Díaz-Sánchez et al. 2017; Paucar-Menacho et al. 2017). One of the important changes that occurs during germination in the amaranth seeds is the structural modification of proteins. It has been reported that albumins and globulins are first modified followed by glutelins (Aphalo et al. 2009). Germination decreased reserve carbohydrates (starch) in A. caudatus and A. cruentus (approximately 30% and 25%, respectively), increased total soluble sugars, and reduced the energy needs of the growing plant. During germination of A. caudatus and A. cruentus the enzyme activity of amylase increases, causing hydrolysis of starch to mono- and oligosaccharides, whereas the content of raffinose and stachyose decreases rapidly during the first 24 h of the process, and almost disappears after 48 h (Gamel et al. 2005). Some researchers reported that amaranth germination positively affects its antioxidant capacity. They attribute this phenomenon to the presence and intensity of light, time, and temperature of germination, and activation of endogenous enzymes such as hydrolases and polyphenol oxidases. In germinated species of A. hipocondryacus, A. cruentus, and A. caudatus, phenolics compounds such as p-coumaric, syringic, ferulic 4-O-caffeoylquinic, 4-O-feruloylquinic acids, and quercetin-3-O-rutinoside (rutin) have been identified. These data indicate that

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germination is an excellent process that can be used to obtain functional foods with high nutritional value and antioxidant capacity (López-Amorós et al. 2006; Paśko et al. 2008, 2009; Duenas et al. 2009; Alvarez-Jubete et al. 2010; Perales-Sánchez et al. 2014; Paucar-Menacho et al. 2017).

1.3.4 Expansion or Popping The use of whole grains as a strategy to increase the consumption of fiber, micronutrients, and phytochemicals present in the outer layer of the grain has gained a lot of attention in the food industry. Processing of amaranth grains requires innovative approaches due to its small seed size, and popping is one of them (Inoue et al. 2009). Popping is a traditional, simple, inexpensive, and rapid method in which the grain is exposed to high temperature for a short time, leading to the explosion of the grain. During the process, the kernel is heated until internal moisture expands and pops out through its outer shell. Superheated vapor is produced inside the grain, which cooks the grain and expands the endosperm, and escapes with great force through the micropores of the grain structure. The heated vapor in the kernel, produced at the time of popping, provides the driving force for expanding the kernel and thus rupturing the pericarp (Inoue et al. 2009; Solanki et al. 2018). The popping process results in changes in the nutritional profile of the grain, such as an increase in protein digestibility, predicted glycemic index, the content of rapidly digestible starch, and lifetime of the product, and inactivation of undesirable microorganisms and certain antinutrients (phytic acid) (Nath et al. 2007; Capriles et al. 2008). Furthermore, the process of popping develops flavors, texture, taste, and improves the acceptability of the final product to render amaranth seeds edible (Sreerama et al. 2008; Llopart and Drago 2016). In precooked amaranth flour obtained by popping, the sample presented very high suspension consistency with low or intermediate water solubility (González et al. 2002). Inoue et al. (2009) designed a prototype of continuous processing systems and concluded that amaranth seeds can be popped under suitable heating conditions.

1.3.5 Milling Amaranth nutrients are not uniformly distributed throughout the grain as with other cereals, but are mainly concentrated in bran and germ fractions of the grain. Due to the structure and morphology of amaranth seeds, it is possible to separate the different botanical parts of grains to obtain milling fractions with different nutritious and dietary specific purposes. For instance, rolling milling, a tradition used worldwide to fractionate cereals to produce milled streams, is a long and gradual grinding process that involves breaking the grains before a reduction passage. Break rolls with fluted surfaces gradually scrap the endosperm from the outer bran layer in a controlled manner (Sakhare et al. 2017). The rolling milling of amaranth generates fractions with unique nutritive compositions and distinct functional properties that can be used as ingredients in the formulation of different food products (Sakhare and Prabhasankar 2017). An alternative method to obtain important fractions of amaranth is the use of ball milling. This process achieves a particle size reduction, causing the rupture of the starch granule, loss in the gelatinization enthalpy, and increases solubility in the

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amaranth flours. Hence, by selecting appropriate operations conditions, ball milling can provide amaranth fractions with particular functional properties desirable for the food industry (Roa et al. 2015). Furthermore, the adaptation of Fourier TransformInfrared spectroscopy (FT-IR) to the ball milling results in a solvent free, sensitive, and non-destructive technology with the advantage of allowing to follow the molecular and structural changes caused by the process. This combined technology is useful to determine the relative proportion of grain components within amaranth milling fractions, as well as to investigate starch modifications provoked by abrasive ball milling and lipid deterioration due to oxidation (Roa et al. 2014; Roa et al. 2015).

1.4 Product Development and Potential Uses of Amaranth Recently, the use of pseudocereals in the food industry, such as amaranth, has increased because of its nutritional value, and processing and storing characteristics. Amaranth grains are considered as an excellent raw material to produce breakfast foods, extruded and expanded products (snacks), bread and baked goods (i.e., cookies, biscuits, candies, and pancakes), pasta and noodles, and soups (Rastogi and Shukla 2013; Burešová et al. 2017; Wu et al. 2017). Thus, it has a tremendous potential in food production. Daily consumption of pseudocereals may provide a variety of bioactive components that have demonstrated physiological benefits in humans, and they might help to reduce the risk of chronic diseases. Future directions in human nutrition involve the discovery and development of the so-called functional foods, whose functions exceed by far the basic nutritional ones. In this section, some of the commercial uses of amaranth will be discussed.

1.4.1 Biofortified Products Biofortification focuses on making plant foods more nutritious as the plants are growing, rather than having nutrients added to the foods when these are being processed. This can be done through plant breeding, transgenic techniques, or agronomic practices (Bouis and Saltzman 2017). With the modern advances in food sciences, biofortification of foods has been utilized as a strategy to introduce microelements in the metabolism of plants to enhance human health. In this regard, the use of elicitors, such as selenium, during germination of amaranth seeds has gained great interest in the food industry. Amaranth sprouts were reported likely to accumulate selenium during their growth (Wu et al. 2017), suggesting that this process might fortify human diet with selenium derivatives known to modulate various signal transduction pathways that influence cell signaling (Brozmanová et al. 2010). One such pathway modulated by selenium includes the NFK-β signaling pathway, which plays an important role in the modulation of inflammation. Wu et  al. (2017) concluded that selenium supplemented amaranth sprouts could be considered as a novel functional food, that could contribute to lower the risk of chronic inflammation-related diseases. Epidemiological data from China suggest that a daily intake of 750–850 μg of selenium sets the upper limit of a safe dose (Yang et al. 1983). Using elicitors during plant growing can be used as a strategy to supplement foods. However, further studies are required to recognize the mechanisms that occur during absorption and bioavailability in animal and human experiments.

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1.4.2 Baked Goods The incorporation of amaranth flours to develop baked goods has been increased in the last ten years. These products have high potential as vehicles of functional ingredients and thus, attractive new products. While protein-rich and gluten-free amaranth flours are used widely in the food industry, the use of amaranth flour or mixture of grains flours have a negative impact on the rheological characteristics (i.e., peak viscosity, cold paste viscosity, and breakdown viscosity) of breads, pastas, snacks, and noodles elaborated with them. The addition of amaranth flours (10%, 20%, or 30%) to basic flours of wheat (refined) or spelt (refined, whole grain) strengthened the dough, mainly by decreasing its extension, and in spelt, containing composite flours, also by increasing the resistance to extension (Mlakar et al. 2009). In these products their physical and sensory properties are frequently inferior to the gluten-based food products (Burešová et al. 2017; Wu et al. 2017). Thus, obtaining high-quality, glutenfree bread is a technological challenge. An alternative to resolve this problem is the use of a combination of ingredients, such as amaranth flour, or rice, or wheat flour/ starch blends to improve expansion, crumb firmness, and sensory evaluation, and thus the acceptability of composite breads (Capriles and Arêas 2014) (see glutenfree products). For instance, the use of amaranth flours at different concentrations (from 20% up to 60%, mixed with wheat flours) to produce cookies resulted in higher protein, fiber, and fat content products as compared with 100% wheat flour cookies (Sindhuja et  al. 2005; Chauhan et  al. 2016). While the addition of amaranth flour changed the rheological properties of the cookie dough, its color, taste, flavor, and surface appearance were optimal. In addition, by increasing the amaranth replacement ratio, the gelatinization temperature, water absorption, development time, and stability of the final product increased. Similarly, the physical characteristics of the amaranth-enriched cookies were affected in a positive way, exhibiting a decrease in bake loss, increased diameter, higher spread ratio, and reduced hardness. Thus, softer textural characteristics, desirable in cookies, were obtained.

1.4.3 Gluten-Free Products Amaranth has recently received special attention as a new ingredient for trendy products in the food industry because it is a gluten-free protein and a great alternative for celiac disease patients. Celiac disease is an autoimmune disease where the ingestion of gluten leads to damage in the small intestine. Thus, food products containing gluten must be eliminated from the diet of patients suffering from this disease. Amaranth grains alone or in combination with other cereals, legumes, or ingredients such as native cassava starch and corn starch have been used to elaborate gluten-free new products such as cookies, bread, snack bars, flours, and baby food (Capriles and Arêas 2014; Padalino et al. 2016). However, the development of products for this population has involved the use of technologies that allows to elaborate gluten-free products but at the same time, retaining the nutritional, functional, and sensory characteristics of the products developed. This has led to the use of other ingredients or a mixture of technologies. For instance, in corn-based snacks, the incorporation of amaranth and quinoa flour (around 50%) can maintain some key physical properties (e.g., high sectional expansion index, stiffness, and water content of extrudates) and the added nutritional value to conclude that amaranth and quinoa could have a tremendous potential

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for the development of gluten-free extruded snacks (Ramos Diaz et  al. 2017). For better functional characteristics, starch modifications are often done to improve the texture and cooking quality of starch, since the starch structural features contribute largely to physicochemical properties to each grain type and the content of protein and soluble fiber could delay gelatinization and retrogradation of starch in amaranth flours (Srichuwong et al. 2017). During elaboration of noodles from amaranth starch, the final products present less cooking loss while increase the cooking time. The alternative developed in the elaboration of noodles with amaranth starch (Amaranthus hypochondrias Durga) is combined with heat-moisture treatment because the noodles present a better taste and aroma compared to amaranth starch or corn starch used alone (Chandla et al. 2017a).

1.4.4 Other Uses of Amaranth A traditional use of popped amaranth in Mexico and other Latin American countries is to mix it with honey to make a cake-like snack. In Peru for example, the amaranth seeds are either popped and used to prepare flours or mixed directly with syrup to make a ball-shaped snack. In the United States, the amaranth seeds are used to make crackers and cookies, and for the preparation of baked goods, and sometimes the whole seeds of amaranth are used to prepare a porridge-like dish. In Nigeria, amaranth seeds are used to prepare porridge flour, or are added to other foods as a strategy to resolve malnutrition-related problems, such as protein-energy malnutrition and micronutrients deficiencies (Rastogi and Shukla 2013). Another important use of amaranth grains is as a substitute for wheat flour in the manufacturing of chicken nuggets. The inclusion of amaranth flour increases the content of minerals, fiber, fat, and protein of the nuggets. It also enhances the emulsion stability, cutting force, porosity, and oil absorption while preserving the overall acceptability of the product (Tamsen et al. 2018).

1.5 Nutritional Properties and Health Benefits of Amaranth 1.5.1 Macronutrients 1.5.1.1 Carbohydrates The amaranth seeds possess low quantities of monosaccharides and oligosaccharides, and a considerable content of polysaccharides, with starch as the major component of this fraction (50%–60%, DW). In Amaranthus cruentus, A. hypochondriacus, and A.  hybridus, small amounts of glucose (0.12%–0.67%) and fructose (0.05%–0.13%) have been detected. These values are significantly higher than those found in cereal grains such as wheat and maize. Oligosaccharides sucrose (0.41%–1.95%) predominates in amaranth, followed by raffinose, maltose, and stachyose (Añon et al. 2009).

1.5.1.1.1 Starch Amaranth is well known for its unique starch content, 4.7%–12.5% amylose, which is an important factor that affects the functional properties of the products made of this starch component (Chandla et  al. 2017b). Starch granules of amaranth have a

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smaller size, ranging from 1.182 to 1.431 μm, in comparison to the starch granules obtained from other commercial cereal starches (wheat, rice, corn, etc.). The smaller size of such granules in amaranth allow for good gelatinization at lower temperatures (~74°C), moderated peak viscosity, better elastic properties, great paste clarity, conservative structure, and A-type difractometric patterns with high crystallinity degrees (~39%). These properties are appreciated in the food industry (Bello-Pérez et al. 2006; Villarreal et al. 2013; Singh et al. 2014). Likewise, the starch granules of amaranth showed tightly packed, angular and polygonal shapes (Chandla et al. 2017b). Studies carried out using differential calorimetry have shown that the maximum deflection temperature corresponding to the endotherm associated with the starch gelatinization varies for different amaranth species between 56°C and 75°C and the heat put into play in this process between 1.2 and 3.4 kcal/g (Bello-Pérez et al. 1998; Añon et al. 2009; Bello-Perez and Paredes-López 2009).

1.5.1.1.2 Fiber Amaranth fiber composition is similar to vegetables and leguminous seeds. Singhal and Kulkarni (1988) reported crude fiber content from 4.9% to 13.5%, DW, for five types of amaranth from India. According to Schnetzler and Breene (1994) the total dietary fiber content on average is about 8% for clear amaranth seeds, whereas in black pigmented seeds it is up to 16%. For these materials, soluble dietary fiber contents are in the range from 30% to 40% and 18%, respectively. Tosi et  al. (2001) evaluated total, soluble, and insoluble dietary fiber content in whole A. cruentus flour and found contents of 14.2%, 8.1%, and 6.1%, respectively. These researchers applied various procedures (grinding, pneumatic classification, and sieving) and reported fractions of whole amaranth flour with total dietary fiber contents of 32.1%–70.8%. Bressani (1994), Pisařikova et al. (2007), and Perales-Sánchez et al. (2014) reported in whole grains of amaranth (A. hypochondriacus L), soluble, insoluble, and total dietary fiber content of 0.47%, 10.20%, and 10.67%, respectively.

1.5.1.2 Lipids The lipid content of most of the cultivated amaranth species range from 5.4% to 9.0%, higher than the lipid content found in cereal grains and lower than that found in soy. The lipid fraction of the amaranth grain is composed of triacylglycerides (80.3%–82.3%), diacylglycerides, monoacylglycerides, phospholipids (9.1%–10.2%), squalene (4.8%–4.9%), phytosterols, tocopherols, and tocotrienols (Gamel et al. 2007; Ogrodowska et al. 2014; ElGendy et al. 2017). Squalene is a triterpene of high economic value. It is a precursor in the synthesis of physiologically important steroids (hormone formation) and, due to its photoprotective effect (Rodas and Bressani 2009; Berghofer and Schoenlechner 2010) and its high oxidation stability (Berganza et al. 2003) it is an essential ingredient in cosmetics and pharmaceuticals. While squalene is usually extracted from fish oils and sharks it is possible to find levels up to 8.0% in amaranth seeds (Gamel et al. 2007; Czaplicki et al. 2012), a value considerably higher than other conventional oils (i.e., maize, soy, and cotton) (Marcone 2005; Paredes-Lopez et al. 2006) and close to the squalene content found in shark oil (Rodas and Bressani 2009). Thus, amaranth oil could be a potential new source of squalene. Interestingly, the hydroperoxide stability test showed that amaranth oil was more stable to oxidation than sunflower oil

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(Gamel  et  al. 2007). This report would be of great interest for the food industry, which could use amaranth grains to develop healthy products with a longer shelf life (Marcone 2005; Ogrodowska et al. 2014; ElGendy et al. 2017).

1.5.1.3 Proteins Amaranth grains possess relatively high levels of protein, ranging from 12.5% to 20%, a percentage slightly higher than that of traditional cereals (maize 8.9%–12.9%, wheat 9.1%–14.0%, oats 16.0%, rice 7.5%–8.7%) (Chávez-Jáuregui et al. 2000) (Table 1.1). The extraordinary nutritional properties of the amaranth grains not only lie in the content of proteins but their quality. They have an excellent balance of amino acids, contain high levels of lysine, and adequate amounts of tryptophan and sulphur-containing amino acids (Met and Cys). Several authors agree that the more abundant protein fractions in amaranth correspond to albumins, globulins, and glutelins with a minor fraction of prolamins (Marcone 2000; Schoenlechner et al. 2008). Several studies have demonstrated TABLE 1.1 Chemical Composition of Amaranth Grain Flour (g/100 of Amaranth Flour) Compound

Content (g/100g)

Carbohydrates Starch Crude fiberb,c Proteina Cystine Aspartic acid Threonine Serine Glutamic acid Proline Glycine Alanine Valine Methionine Isoleucine Leucine Tyrosine Phenylalanine Histidine Lysine Tryptophan Arginine

63.0–65.8 62.70 3.03–8.8 15.83 0.55 1.43 0.50 0.91 2.73 0.66 1.28 0.63 0.77 0.53 0.63 0.93 0.44 0.73 0.46 1.02 ND 1.47

a b c d e

Compound Lipidsb,c,d Triacylglycerold Fatty acidse Palmitic Oleic Linoleic Linolenic Squalened Phospholipidsd Tocopherolsd,e α-TOH β-TOH γ-TOH Ashb,c,d

Chávez-Jauregui and Silva (2000); Akin-Idowu et al. (2016); Rastogi and Shukla (2013); Gamel and Mesallam (2007); Ramos-Días et al. (2017); ND: Not Detected; TOH: Tocopherol.

Content (g/100g) 6.8–8.5 5.46–6.99 0.93 1.26 2.45 0.05 0.32–0.41 0.61–0.86 0.79 2.05 0.14 2.41–4.03

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that amaranth storage-proteins have good emulsifying, foaming, jellifying, and film foaming properties, as well as a good water retention capacity (Silva-Sánchez et  al. 2004; Bolontrade et al. 2013; Suarez and Añón 2018). While amaranth proteins have an average isoelectric point (PI) of 4.5, they present reduced solubility at pH close to neutrality, and under high ionic strength conditions, such characteristics represent a limitation for the use of these proteins in the food industry (Bolontrade et  al. 2013; Suarez and Añón 2018). Additionally, amaranth proteins have the capacity to form and stabilize emulsions (oil-in-water), thus, emulsions at high protein concentration are suitable to be used as transport of different bioactive components (Suarez and Añón 2018).

1.5.2 Micronutrients 1.5.2.1 Vitamins and Minerals Amaranth species contain riboflavin, niacin, ascorbic and folic acids, thiamine, and biotin, all of which are necessary in a proper diet. In the three cultured amaranth species, the riboflavin content is higher than that for cereal grains, while the contents of thiamine and niacin are at low levels compared to their content in cereals (two to three times higher) (Teutonico and Knorr 1985; De Ruiz and Bressani 1990). The content of vitamins varies between species. For A. cruentus and A. hypochondriacus, contents of thiamine, riboflavin, and niacin in a range of 0.008–0.07, 0.43–0.3, and 0.2–1.21 mg/100 g, respectively, have been reported (Singhal and Kulkarni 1988; De Ruiz and Bressani 1990). Amaranth grains are also recommended as a good source of minerals. The mineral content has low variability among amaranth species (2.6%–4.4%). Amaranth contains important macrominerals such as Ca, K, Mg, and Na, and microminerals like Cu, Fe, Mn, and Zn. These grains have higher quantities of Ca, P, and Fe than that found in traditional cereals (Rybicka and Gliszczynska-Swiglo 2017; Temesgen and Bultosa 2017).

1.5.3 Biocomponents 1.5.3.1 Phenolic Compounds A great variability of phenolic compounds has been reported in amaranth seeds. In different varieties of amaranth (Tulyehualco, Nutrisol, DGETA, and Gabriela) the phenolics acids: vanillic, 4-hydroxybenzoic, 4-syringic, and caffeoylisocitric acids (de la Rosa et al. 2009; Vollmer et al. 2017), the flavonoids: rutin (4.0–10.2 μg/g flour), nicotiflorine (4.8–7.2 μg/g flour), and isoquercitrin (0.3–0.5 μg/g flour) (de la Rosa et al. 2009), whereas in A. cruentus, cultivated in Kenya, a high content of condensed tannins (2.55 mg/100 g) has been observed (Suryavanshi et al. 2007; Kunyanga et al. 2011; Vollmer et al. 2017). Other compounds identified in A. cruentus are betacyanins, caffeoylisocitric acid (which is a source of several esterified phenolic acids), and chlorogenic acid. Betacyanins found in sprouts of A. cruentus have been reported to have anti-inflammatory effects on RAW 264.7 macrophages by preventing the TNFα induced translocation of NFκB to the nucleus followed by a decreased release of IL-6 from LPS activated cells (Tyszka-Czochara et al. 2016). One of the beneficial effects of amaranth consumption is associated with the presence of polyphenols in these grains. These compounds have been directly correlated with antioxidant capacity reported in these grains (Vollmer et al. 2017).

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1.6 Nutraceutical Properties and Potential Health Benefits of Amaranth 1.6.1 Antioxidants and Free Radical-Related Diseases The free radicals (FRs) are extremely reactive species. Because of their unpaired electron, FRs oxidize any neighboring molecule, altering its structure and turning it into other FRs, thus generating a chain reaction. To counteract the detrimental effect of FRs, living organisms have developed an elaborate antioxidant defense system that includes enzymes (superoxide dismutase, catalase, and glutathione peroxidase) and different endogenous and exogenous molecules. Within the latter group are those antioxidant compounds that are provided by the diet such as phenolic compounds, carotenoids, and vitamins (Vinson et al. 1998; Hannum 2004). Amaranth grains possess chemical compounds such as phenolics and carotenoids, which can contribute with the antioxidant capacity of the grain. Czerwinski et al. (2004) determined the antioxidant activity in methanolic extracts of A. hypochondriacus. Amaranth extracts showed an antioxidant activity of 23.2%–26.0% equivalents of β-carotene. These researchers also evaluated the relationships between the antioxidant capacity and the content of phenolics in amaranth and found that the best correlation existed between the antioxidant activity and total phenolics. Conforti et al. (2005) evaluated the antioxidant activity (phenolic content) in two varieties of A. caudatus (Oscar Blanco and Victor Red). The antioxidant activity was assessed using a lipid peroxidation assay. They did not find a significant statistical difference in the antioxidant activity of both species. On the other hand, the effect of amaranth grain consumption on the oxidative stress in plasma and tissues (heart, kidney, and pancreas) of mice were evaluated (Paśko et al. 2011). Animal subjects were supplied with fructose to induce oxidative stress; this was manifested through the increase in malondialdehyde and the decreased activity of enzymes with antioxidant capacity in plasma and tissues. The consumption of amaranth grains (310 and 155 g/kg in diet) restored the activity of some enzymes, decreased the malondialdehyde and increased antioxidant activity (assessed by Ferric Reducing Ability of Plasma [FRAP]) and the activity of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase. The results showed that, depending on the quantity of amaranth grain consumed, we can have a protective effect against the changes generated by oxidative stress by reducing lipid peroxidation and increasing the antioxidant enzyme activity in plasma and tissues.

1.6.2 Antihypertensive and Anti-inflammatory Properties Hypertension is a risk factor for developing cardiovascular diseases such as coronary heart disease, atrial fibrillation, and heart failure. Some proteins from grains such as soybeans, chickpeas, and amaranth contain peptide sequences with bioactive functions. Some of these include antihypertensive properties. Peptides obtained from amaranth (alcalase pH = 7.01, temperature = 52°C, enzyme concentration = 0.04 mU/mg of protein, and time = 6.16 h) showed a 93.5% of ACE (angiotensin converting enzyme) inhibition and a hydrolysis degree of 74.77%. Furthermore, after supplementing spontaneously hypertensive rats with the hydrolyzate, (which was bioavailable after 5–60 min, and the hypotensive effect started at 4 h) the effect was similar to captopril

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(control) (Ramírez-Torres et al. 2017). Likewise, amaranth sprout proteins presented a capacity to inhibit ACE similarly to other plant proteins (IC50 = 0.9 ± 0.6 mg/mL). This capacity increased after in vitro gastrointestinal digestion (IC50 = 0.26 ± 0.07 mg/ mL) (Aphalo et al. 2015).

1.6.3 Cholesterol-Lowering Effect Amaranth oil is a good source of squalene. Besides the antioxidant properties attributed to this triterpene, squalene is an inhibitor of hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase, an enzyme that participates in the endogenous synthesis of cholesterol. During cholesterol synthesis, the HMG-CoA reductase specifically catalyzes the conversion of HMG-CoA to mevalonate, a precursor of endogenous cholesterol. By inhibiting this enzyme, the amounts of mevalonate are reduced and therefore the hepatic and plasma cholesterol levels (Huang et al. 2009). Similarly, in a recent publication (Hien et al. 2017), it was found that squalene can induce the mRNA expression of liver X receptors (LXRs) and their target genes (ABCA1, ABCG1, ApoE). These genes control the reverse transport of cholesterol and thus, cholesterol homeostasis, therefore their transcript increase resulted in removal of cholesterol from the cells and overall inducing a hypocholesterolemic effect.

1.6.4 Fiber and Glycemic Index Control—Diabetic Patients The importance of dietary fiber to health is related to different factors that include promoting gastrointestinal health and a regular intestinal transit, prevention of polyps and irritable bowel syndrome, and reduce constipation, among others. As discussed previously, amaranth seeds are a source of soluble and insoluble fiber. Dietary fiber is known to have a beneficial impact on health, due to the decrease in levels of serum cholesterol, low density lipoproteins (LDL) cholesterol, and triacylglycerides, and because it possesses a very low glycemic index, it can also improve insulin sensitivity. In addition to the fiber properties, it has been demonstrated that peptides released from amaranth proteins could have a negative effect against dipeptidyl peptidase IV (DPPIV), an enzyme that deactivates incretins, hormones involved in insulin secretion. Hence, the use of DPPIV inhibitors increases the time of action of incretins and insulin. Peptides from A. hypochondriacus released after simulated gastrointestinal digestion, showed an IC50 of 1.1 mg/mL in a dose-dependent manner. The methanolic extracts (concentration 25 mg/mL) of the varieties Oscar Blanco and Victor Red showed an antidiabetic activity of 50.5% and 28%, respectively. Other seeds, such as soybean, black bean, and wheat were also tested. However, the highest inhibition of DPPIV was observed with amaranth peptides (Velarde-Salcedo et al. 2013). This suggests that amaranth hydrolyzate could be used to improve insulin sensitivity and in the prevention of diabetes.

1.7 Conclusion Amaranth grains have been recognized as a complete food due to their excellent quality proteins and well-balanced amino acid composition and the high levels of dietary fiber, vitamins, minerals, and antioxidants. The amaranth proteins have essential

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bioactive peptides which may act as modulators of metabolism and possess other outstanding biological activities, such as anti-inflammatory, antihypertensive, and antidiabetic properties. Most of the phytochemicals in amaranth grains are the various polyphenols. These compounds possess additional health benefits, especially the antioxidant activity, which is critical in reducing the risk of oxidative stress-related chronic diseases. In addition, amaranth seeds are recommended as safe for people with gluten allergies and celiac disease. All these characteristics make amaranth grains not only a highly valued food but also a novel functional ingredient of specialty foods. Further research is needed to identify amaranth seeds’ bioactive compounds related to the observed effects and their mechanisms, validating the results in humans. With the advances of different molecular tools and expression of key amaranth genes and subsequent production of recombinant protein in diverse biological systems, amaranth proteins are the primary target of researchers addressing their nutritional and nutraceutical potential. New varieties rich in bioactive components, bioprocesses increasing such components, and their incorporation into functional foods are also critical areas for future research.

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2 Barley Paras Sharma and T. Longvah CONTENTS 2.1 2.2

Introduction....................................................................................................... 25 Processing of Barley ......................................................................................... 27 2.2.1 Dehulling and Pearling ......................................................................... 27 2.3 Product Development........................................................................................ 29 2.3.1 Rolling and Flaking .............................................................................. 29 2.3.2 Roasted or Puffed Barley ...................................................................... 30 2.3.3 Baked Foods .......................................................................................... 30 2.3.4 Extruded Foods ..................................................................................... 32 2.3.5 Pasta and Noodles ................................................................................. 32 2.4 Nutritional Aspects ........................................................................................... 32 2.4.1 Nutritional Composition........................................................................ 32 2.4.2 Bioactive Constituents ........................................................................... 35 2.4.2.1 Beta Glucan ............................................................................ 35 2.4.2.2 Phenolic Compounds .............................................................. 36 2.4.2.3 Flavonoids............................................................................... 36 2.4.2.4 Arabinoxylan .......................................................................... 37 2.5 Health Benefits.................................................................................................. 38 2.6 Conclusion ........................................................................................................ 39 References .................................................................................................................. 39

2.1 Introduction Whole grains have been a part of the human diet since the beginning of agriculture around 10,000 years ago and for the first 3,500–4,000 years, human diet consisted only of whole grains. Later on, particularly in last century, refined grains became a part of the human diet due to the development of machines and mills involved in grain refining processes. The shifting of food consumption patterns from whole grains to refined grains showed significant adverse health effects, which are visible in the form of noncommunicable diseases (NCDs) including diabetes, heart disease, and other chronic diseases. Therefore, in the last few years, interest has grown around the consumption of whole grains, and it is a well-established fact that consumption of whole grains has pronounced positive health effects.

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Barley (Hordeum vulgare L.) is among the most important cereals, cultivated to a large extent worldwide and is ranked fourth in cereal production. In the year 2015–2016, barley production equaled 147 million tonnes worldwide (FAO, 2017). It was among the first domesticated food crop, originating in the Israel–Jordan region (Sharma & Kothari, 2017) from its wild relative Hordeum spontaneum. Barley crops can survive under versatile environmental and soil conditions including high and low temperatures, as well as alkaline and acidic soil conditions (Newman & Newman, 2008; Sharma & Gujral, 2010). Barley has been an important food crop for several regions across the globe including the Middle East, North Africa, and Northern and Eastern Europe (England, Denmark, Russia, Poland, Iran, Morocco, Ethiopia, and Finland) and in Asia (Japan, India, Tibet, and Korea) (Harlan, 1979; Zohary & Hofp, 1988; Newman & Newman, 2006; Sharma & Gujral 2010a). Before the origin of wheat, barley was consumed as a major staple cereal, but gradually it was replaced by wheat, and barley utilization diversified towards malting, brewing, and animal feed (Bonoli et al., 2004; Baik & Ullrich, 2008). Barley is classified into different types, depending upon growing condition (spring or winter), spikelets (two-row or six-row), chemical composition (high lysine type, high amylose type, high amylopectin starch type), presence of hull (hulled barley) and absence of hull (hull-less or naked barley), and on the basis of color (colored or normal) (Wiebe & Reid, 1961; Baik & Ullrich, 2008). Both hulled and hull-less barley contains a fibrous hull, but in hull-less barley the husk is loosely adhered to the grain and easily removed during threshing, and morphologically the grain is almost similar to wheat. In contrast to hull-less barley, hulled barley contains a fibrous hull strongly adhered to the grain and remains intact even after threshing. Hull-less barley is thought to be suitable for food purposes, while hulled is widely used for malting and brewing purposes. Hulled barley can be used as food, but an additional processing step called “dehulling” is required before use (Sharma & Gujral, 2010b, 2011, 2013; Sharma et al., 2011). Colored barley is pigmented and has a wide range of colors, such as black, green, blue-green, and purple, due to the presence of anthocyanin pigment and is reported to have very high levels of polyphenols and antioxidant potential (Kim et al., 2007). Barley is considered a “healthy” grain because it contains a high amount of β-glucan, water and fat-soluble vitamins like B-complex, tocopherol, and tocotrienols (Chatterjee et al., 1977; Baik & Ullrich, 2008). It also contains the highest levels of polyphenols among the cereals. The concentration of phenolic compound in barley is very high in the outer layers of the grain, and found in free and bound forms. The major phenolics identified in barley are benzoic and cinnamic acid derivatives, flavonols, quinines, proanthocyanidins, chalcones, flavones, flavanones, and amino phenolic compounds (Goupy et  al., 1997; Sharma & Gujral, 2010a). These polyphenols function as reducing agents, free radical scavengers, singlet oxygen quenchers, and potential complexer of prooxidants, and therefore, can reduce the risk of various diseases. Barley has a high level (up to 6% average) of β-glucan, which is a water-soluble polysaccharide considered soluble dietary fiber. It is a linear chain of β-glucopyranosyl; about 70% is linked (1→4) and about 30% is linked (1→3). The (1→3) linkages occur singly and are separated by a sequence of generally two or three (1→4) linkages (Izydorczyk & Dexter, 2008; Sharma & Gujral, 2014a, 2014b, 2014c). Barley β-glucan has been shown to have health benefits for heart patients by reducing blood pressure (Behall et al., 2006), lowering serum cholesterol

Barley

27

FIGURE 2.1 Structure of barley grain. (From NIIR Board of Consultants & Engineers, 2006.)

and visceral fats, and is effective against certain types of cell proliferation. The U.S. Food and Drug Administration (FDA) has permitted that whole grain barley and barley-containing products can carry a claim that they reduce the risk of coronary heart disease, and recommended daily consumption of β-glucan of at least 0.75 g per serving, or total 3 g, to prevent certain diseases including coronary heart disease. Therefore, foods that contain the recommended amount of β-glucan per serving are considered healthy foods. Similar health claims were also approved for oats and barley β-glucan in Canada and the European Union (European Food Safety Authority, 2011). However, per capita barley consumption has drastically decreased from 4  kg/year in 1961 to 0.97  kg/year in 2013, while production of barley has increased in last half century. The data shows that most of the produced barley is being utilized by malting and the feed industry. The structure of hulled barley is shown in Figure 2.1. Barley contains a number of beneficial compounds and high nutritive value and therefore, it should be utilized in foods and its consumption should be encouraged to take health benefits from its numerous bioactive compounds. This chapter sheds a light on the nutritional profile and bioactive constituents of barley, and its utilization in different food products.

2.2 Processing of Barley The harvested barley grain may contain various amounts of contaminants including other grains, weed seeds, and foreign materials, such as stones, straw, chaff, and dust, that will affect the processing and quality. Generally, the cleaning of barley grain can be achieved with equipments commonly used for other grains, such as magnets, aspirators, gravity tables, destoners, and screens.

2.2.1 Dehulling and Pearling The hull consists of 10%–15% of the barley grain and dehulling is the process in which the hulled portion of barley is removed using a pearling or blocking machine. Covered barley, in which the hull tightly adheres to the kernel, and hull-less barley, with the hull not entirely removed from the kernels during threshing, need to he dehulled

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before further processing for human consumption. Dehulling is usually accomplished in pearling machines or in compressed air dehullers that use a stream of pressurized air to apply a mechanical shock to a sample of barley grains, which knocks the hulls off the kernels. Hulls are subsequently removed by aspiration. Recently, hulled barley has also been dehulled using a rice polisher (Sharma & Gujral, 2010a). Hull-less barley contains a loosely bound hull that is easily removed during the threshing of grains similar to wheat (Baik et al., 2008). Dehulled barley may be further subjected to a pearling process that removes the bran, germ, and hull, which may remain after dehulling. Depending upon the degree of milling, bright white barley that has a more appealing surface can be produced. The dehulling and pearling processes also significantly change the barley composition. Apart from physical changes, the pearling process improves the β-glucan and starch content, but reduces dietary fiber, protein, and lipid content in the grain (Bhatty, 1998; Peterson et al., 2008). Dehulled and pearled barley can be further ground to produce whole and pearled barley flour using different mills such as a hammer mill or a pin mill. Roller milling of barley is also possible to produce different streams of flours (Bhatty, 1993; Sharma & Gujarl, 2010a). Barley grits and flakes can be produced from whole and polished grains. Cleaner, free flowing, and fine-particle size flour can be produced using a roller mill, which is not possible by using other mills. This method is not commercially available but it is standardized at the laboratory scale (Bhatty, 1993; Kiryluk et al., 2000; Sharma & Gujral, 2010a; Izydorczyk et al., 2014b). Interestingly, roller-milling equipment that is used for wheat can be utilized for barley to produce special grade flour rich in starch, β-glucan, tocols, and biological active compounds. Unlike wheat bran, barley bran is brittle and thus easily fragmented into small particles that are difficult to separate from the starchy endosperm, and therefore, what is produced is high in ash content, off-white in color, and has black spots. In addition, another problem associated with barley roller milling is flake formation from endosperms instead of fragmenting into small particles after passing through the rollers during milling, which leads to slow sifting and low flour yield. This is possibly due to the high content of polysaccharides, including β-glucan and arabinoxylan, in barley. Besides these limitations, efforts have been made to produce white barley flour using roller milling that includes modification of roller milling procedures such as altering screen size, adjustment of roller distance (Izydorczyk et  al., 2003; Flores et al., 2005), and adjusting the moisture content (tempering) to increase flour yield, purity, and better color (Bhatty, 1997; Izydorczyk et al., 2003). Sharma and Gujral (2010b) roller milled different barley cultivars after dehulling and reported the extraction rates varied between 51.1% and 62% while Bhatty (1999) reported the flour yield up to 60%. Izydorczyk et al. (2003) reported extraction rates ranging from 51.1% to 63.1% for roller milled barley cultivars. It is speculated that the extraction rate of barley flour upon roller milling is influenced by several factors including moisture content, grain hardness, polysaccharide content, and barley type (waxy starch/ high amylose starch/regular starch) (Bhatty, 1997; Klamczynski & Czuchajowska, 1999). Pearling of barley and tempering of grain to a slightly higher moisture content (up to 16%) significantly improved the flour color but drastically decreased the extraction rate (Bhatty, 1997). Stone milling has certain advantages over roller milling, such as easy handling, relatively lower maintenance costs, and one step grinding. Stone milling is also used for production of fiber-rich fractions (FRF) by feeding the grain through the stone

Barley

29

mill three times and then sieving, followed by three passages across the shorts duster (Izydorczyk et al., 2014a). Pin milling is also used for the production of whole barley flour or barley FRF. The grinding of grains in a pin mill is achieved by impacting grain particles with a series of strong steel pins. The grain particles are fragmented in small pieces as they move towards the outlet. Alteration in feed rate and motor speed could be used to control the grinding action of the pin mill. Using these grinding regulating parameters, Izydorczyk et al. (2008) used the pin mill at two different rotor speeds to obtain barley FRF. These fractions were then refined using additional steps of pin milling and sieving.

2.3 Product Development Mostly a large proportion of produced barley is utilized for malting/brewing and feed purposes across the globe. Certain reasons limit the food uses of barley, including lack of gluten protein, high polyphenol oxidase (PPO) activity, gumminess and blunt mouth feel, and fibrous hulls. Barley has been a staple food in a few countries, (Newman & Newman, 2006). Flour from roasted barley, which is called sattu in India and tsampa in Tibet, has been a major source of dietary fiber for the people of those countries (Tashi et al., 2002; Mridula et al., 2007; Sharma et al., 2011). Whole barley grain has also been utilized for making roasted barley and puffed barley (Mariotti et al., 2006; Sharma et al., 2011; Sharma & Gujral, 2014a, 2014b). However, consumers from several countries are not aware about such whole barley-based foods but do consume pot and pearled barley, which is often used for preparation of barley soup (Ames & Rhymer, 2008). Interest in barley-based foods has grown rapidly in recent decades due to accelerated research in barley food product development. New foodspecific barley varieties have been introduced, as well as new milling techniques that ease the milling process without contaminating barley flour with hulls. The newly developed technology also offers the barley-based foods with higher consumer acceptability and palatability. These efforts also resolve the technological problems associated with the gluten-free nature of barley, by blending the barley flour with wheat flour, as well by the addition of certain binders and gums for development of leavened baked food products. On the other hand, food products such as extruded food, cookies, and chapatti have been developed successfully. Nowadays, a wide range of barley-based foods is available, such as breakfast cereals, snack foods, pasta, bakery products, beverages, etc. These food products could be used as alternatives to wheat-based food products (Sharma & Gujral, 2014a, 2014b).

2.3.1 Rolling and Flaking Rolling and flaking is one of the methods of barley processing that is similar to rice flaking or rolling. Pearled barley is relatively easy to cook, but nutritional value and bioactive constituents are high in whole grain barley. But there are several problems associated with whole barley consumption including high cooking time, slow rate of water imbibition, and gummy mouth feel. Therefore, rolling and flaking is a very effective process to overcome these technological and sensory predicaments. Barley grain is rolled to crack in order to improve the surface area and enhance the water uptake, which consequently reduces the cooking time (Baik, 2014). This process

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involves dehulling of grains followed by tempering or soaking for 30–40 h to increase the moisture levels of the grains to a desired level, then steaming (105°C–120°C) and rolling using revolving heavy rollers, followed by drying.

2.3.2 Roasted or Puffed Barley Both hulled and hull-less whole barley grains can be puffed similar to rice. Roasting of barley can be carried out at 250°C–280°C in hot sand or in a microwave as well (Sharma & Gujral, 2011). Roasting improves the texture, color, and flavors, and increases digestibility, enhances crispiness, increases volume, and reduces the antinutrients (Hoke et al., 2007). Roasted barley can be consumed directly, or flour obtained from roasted barley can be used for preparation of different barley-based foods by incorporating it with other cereal flour.

2.3.3 Baked Foods A number of baked foods including cakes, cookies, chapattis (flatbread), bread, and pancakes have been prepared from whole grain barley flour as well flour obtained from pearled barley (Gill et al., 2002a; Gujral & Gaur, 2005; Holtekjolen et al., 2008; Newman & Newman, 2008; Frost et al., 2011; Sharma & Gujral, 2014a, 2014b; Moza & Gujral, 2017; Sharma et al., 2017). Lack of gluten protein is a major technological problem associated with barley, therefore it is difficult to prepare leavened food products from barley alone (Newman & Newman, 2008). However, efforts have been made to replace barley flour with wheat flour up to a certain level (30%–40%) for preparation of acceptable quality bread (Morita et al., 1998; Jacobs et al., 2008). Barley has not been widely utilized for cookie-making and only limited studies are available. Cookie-making from barley is relatively easier than leavened baked products because gluten protein is not essential in the cookie-making process. Sharma and Gujral (2014a) replaced barley flour with wheat flour at levels of 25%–100% and observed that the overall acceptability of the cookies decreased with the increased level of barley flour incorporated; however, the cookies made from 100% barley flour remained acceptable, receiving a hedonic sensory score of 7.1 by the panel (Figure 2.2). Frost et al. (2011) reported that cookies prepared from incorporation of

FIGURE 2.2 Effect of incorporation of whole barley flour in wheat flour on quality of cookies. Control (100% wheat flour), WBF-25% (wheat-barley flour blend with 25% barley flour), WBF-50% (wheat-barley flour blend with 50% barley flour), WBF-75% (wheat-barley flour blend with 75% barley flour), and WBF-100% (100% barley flour). (From Sharma, P., Processing and utilization of barley Hordeum vulgare L. in human foods for its β-glucan content, PhD thesis, 2012.)

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barley flour at a level of 70% were acceptable to the consumer. Barley bran along with wheat flour has also been used for biscuit-making. Sudha et al. (2007) reported that 20% incorporation of barley bran in wheat flour did not affect the sensory quality of biscuits but further increase in the level of barley bran decreased the acceptability of biscuits. Flatbreads and tortillas are historically popular in different parts of the world including the Middle East, Eastern African, and Northern Europe. Barley flour could be utilized for flatbread-making to increase the level of β-glucan and dietary fiber content (Baik, 2014). Similar to cookie-making, limited studies have also been carried out to utilize whole barley flour for flatbread-making (or chapatti-making). Turkish flatbread was prepared by incorporating 40% barley flour; however, a slight decrease in sensory score was noticed (Basman & Koksel, 1999). Incorporating whole barley flour up to 28% in whole wheat flour did not affect sensory acceptability of chapattis (Figure 2.3). However, chapattis prepared from wheat-barley blends containing 56% whole barley flour into wheat flour were moderately acceptable due to gummy taste of barley flour and non-wheatish aroma and flavor (Sharma, 2012). Further incorporation of barley flour to wheat flour at levels of 84% decreased the sensory score drastically and chapattis were unacceptable due to irregular shape by dilution of gluten, gummy mouth feel, barley characteristics flavor/aroma, and lighter color (Sharma & Gujral, 2014b). Knuckles et al. (1997) reported that 20% incorporation of barley flour in wheat flour produced bread with acceptable sensory attributes; however, increasing the level of barley flour up to 40% decreased the sensory quality of bread. Ereifej et al. (2006) reported that Balady bread prepared by incorporating barley flour at level up to 30% produced bread with acceptable sensory quality; however, further incorporation of barley flour decreased the sensory characteristics of bread. Extensibility of chapatti prepared from barley-wheat blends was maintained when 20% barley flour was added, while increasing the levels of barley flour exhibited decrease in extensibility and dough-handling characteristics (Gujral & Pathak, 2002).

FIGURE 2.3 Effect of incorporation of barley flour on chapattis. Control (100% wheat flour), BF-28% (wheat-barley flour blend with 28% barley flour), BF-56% (wheat-barley flour blend with 56% barley flour), and BF-84% (wheat-barley flour blend with 84% barley flour). (From Sharma, P., Processing and utilization of barley Hordeum vulgare L. in human foods for its β-glucan content, PhD thesis, 2012.)

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2.3.4 Extruded Foods Extrusion cooking is a very popular method of food processing across the globe due to its many advantages such as fast processing, versatility, and low cost. Also, the products made by extrusion cooking have a long shelf life due to low moisture content (Santillan-Moreno et al., 2011). This process is also useful for development of food with high fibers (Camire & King, 1991). Grits from whole barley have been used to develop extruded food products, and feed moisture and extrusion temperature significantly affect the sensory and textural attributes of the extrudates (Vasanthan et al., 2000; Thymi et al., 2005). Wang et al. (1993) developed the extrudates using barley in combination with wheat and rye. Snack food has been prepared using barley-tomato pomace, which had good sensory acceptability (Alten et  al., 2008). High sensory acceptability has been observed for extruded food products prepared from barley-rice in 50:50 ratios as compared to 100% barley extrudates (Berglund et al., 1994).

2.3.5 Pasta and Noodles Pasta is a wheat-based food product that is prepared from semolina of durum wheat; however, efforts have been made to develop pasta from wheat-barley blends. The major concern with barley-based pasta includes high gruel loss during cooking, low strength, dark color, and lower elasticity, which are due to dilution of gluten protein in the blends. Pasta containing 20% barley has been successfully prepared without affecting sensory properties; however, the color of the pasta was slightly dark as compared to the control (Knuckles et al., 1997). Barley fraction rich in β-glucan has been incorporated up to 50% in wheat semolina for pasta-making, and the quality parameters of the pasta were acceptable, though the color of the pasta was darker (Marconi et  al., 2000). PeParaio and CoMenDaDor et  al. (2008) produced pasta containing barley flour up to 30% with acceptable sensory properties. Noodles are also an important food consumed widely in various parts of world, such as East Asian countries. Barley flour incorporation in wheat flour has similar concerns as for pasta. Barley has very high polyphenol oxidase activity (PPO) (Sharma & Gujral, 2010a), which leads to dark color of barley-based foods. Many researchers have incorporated barley flour successfully without affecting the sensory characteristics of the noodles (Baik & Czuchajowska, 1997; Hatcher et al., 2005; Lagasse et al., 2006). Barley flour up to 40% can be easily incorporated in wheat flour for Asian noodle-making (Baik, 2014).

2.4 Nutritional Aspects 2.4.1 Nutritional Composition Barley is considered a nutritious cereal due to its unique and balanced nutrient compositions. However, composition of any plant food is affected by several key factors, including environmental condition where they grow, soil composition, agriculture practices, genotype, and nutrient supply (Torp et  al., 1981; Henry, 1986; Peterson & Qureshi, 1993). Starch is the major portion of the barley kernel, which ranges between 58% and 64% with a large variation of amylose content between 20% and 30%. However, waxy barley contains very low levels of amylose (1%–5%) while high

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amylose barley has amylose as high as 45%–48%. Interestingly, waxy barley contains slightly lower (5%–8%) levels of total starch but high levels of simple sugars including glucose, fructose, and sucrose, and fiber components including β-glucan (Xue et al., 1997). Simple sugars are also present in barley grain, although these are found in low concentration (Henry, 1988). Monosaccharides such as glucose and fructose are found in mature barley at low levels usually quinoa > amaranth. Among the pseudocereals, buckwheat has the highest final viscosity, which is an important indicator of the strength of the gel formed upon cooling, and better pasting property, which may be due to smaller particle size of starch and higher amylose content (3.5%–19.6% for quinoa, 8% for amaranth, and 47% for buckwheat starch) (Alvarez-Jubete et al., 2009). Loaf volumes were increased for buckwheat bread (1.63 mL/g) in comparison with the control (1.3 mL/g). Also, it has a darker color and softer crumbs than the control, and the increase in crumb hardness was only significant after 120 h of storage time. No significant difference in the acceptability of the pseudocereal baked bread in comparison to the control was observed. Chinese steam bread is a staple food in Northern China. Hydrothermally processed tartary buckwheat flour showed a decrease in rutin loss and bitterness in Chinese

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steam breads, Deactivation of rutinosidase in buckwheat flour is important because during processing, rutin is converted to quercetin but the bioavailability of quercetin is poor compared to rutin (Wang et al., 2017).

4.3.1.3 Use of Fermented Buckwheat Flour in Muffins and Biscuits Unfermented buckwheat flour has poor baking performance and sensory attributes. It is believed that fermented buckwheat flour can be an alternative ingredient for improving the functional properties of bakery products. Research has been done on developing gluten-free muffins using the fermented buckwheat flour (F. esculentum Moench) and resulted in a significant increase in antioxidant activity, activity against the protein glycation advanced glycation end-products (AGEs) formation, lysine content, FAST index, and browning index compared to the muffins made with unfermented buckwheat flour, or fermented and unfermented corn flour (Zieliński et al., 2017). Buckwheat is a good source of lactic acid bacteria, which have the potential to produce compounds like alcohols, carbonyl substances, organic acids, and other substances that influence the taste and flavor of fermented products. In a study, 14 strains of lactic acid bacteria were used for the development of buckwheat water biscuits and the control was a common unfermented buckwheat flour water biscuit. A nicer, glossier, and smoother surface of the biscuits was obtained from the fermented buckwheat flour than from the unfermented one, and water biscuits made of buckwheat flour fermented by Lactobacillus plantarum gave the highest content of soluble proteins.

4.3.2 Other Miscellaneous Uses of Buckwheat Flour Other uses of buckwheat flour include: buckwheat honey, a low viscosity reddish-brown product with a strong animal aroma and rich in flavonoid and phenolic content with higher antioxidant capacity than other honey; buckwheat tea, a popular health beverage in Asian and European countries, is made of common and tartary buckwheat leaves and flowers and is rich in flavonoids, especially rutin and other compounds, such as quercetin and flavone C-glucosides; buckwheat tarhana, a traditional fermented cereal food (soup), prepared by mixing wheat products, yoghurt, some vegetables, and spices, and in which the addition of buckwheat has improved the nutritional contents in terms of fat, protein, ash, and lysine content (Giménez-Bastida et al., 2015). Some traditional buckwheat dishes and bakery products include: soba-kiri (noodles)  in Japan, ma-er-duo (cat earlobe) and chaomai-ke (buckwheat shell) in China, crepes in France, muk in Korea, Zlevanka in Europe, blini in Russia, and pizoccheeri in Italy (Ikeda, 2002).

4.4 Nutritional and Chemical Composition of Buckwheat 4.4.1 Nutritional Properties Flint-stone milling of common buckwheat yields 55.4% flour, 24.2% bran, and 17.4% husks, with 3.0% milling losses. Flint-stone milling of tartary buckwheat yields 55.6% flour, 24.4% bran, 15.7% husks, with 4.3% milling losses (Bonafaccia et al., 2003). Buckwheat groats contain a total carbohydrates of 67.8%–70.1%, of which starch

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content was 54.5%, and is a good source of resistant starch (Wijngaard and Arendt, 2006), protein (12.11%–14.47%), lipids (3.25%–3.3%), and ash (1.7%–2.33%) based on dry matter (Amudha Senthil, 2015; Deng et al., 2015). The bran of both common and tartary buckwheat is a dietary source of Zn and Se (Bonafaccia et al., 2003).

4.4.1.1 Carbohydrates Buckwheat is a good source of resistant starch and amylose with total carbohydrates of about 70%. An important compound is found in buckwheat seed called fagopyritols, which is a derivative of D-chiro-inositol. It can be used as a dietary supplement, as it is readily hydrolyzed by α-galactosidase, releasing D-chiro-inositol, and lowers plasma glucose in subjects with noninsulin-dependent diabetes mellitus (Steadman et  al., 2000). The fagopyritols content of common buckwheat and that of tartary buckwheat are 70% and 21% of total soluble carbohydrates, respectively.

4.4.1.2 Proteins Proteins of buckwheat are composed of different amino acids and are listed in Table 4.1 and contain about 40.77 mg/100 g (dry matter) of essential amino acids with the most abundant being glutamic acid followed by arginine, aspartic acid, and serine TABLE 4.1 List of Amino Acids in the Bran and Flour of Common and Tartary Buckwheat g/100 g Protein Buckwheat (Fagopyrum esculentum)

Buckwheat (Fagopyrum tataricum)

Amino Acids

Bran

Flour

Bran

Flour

Threonine Isoleucine Leucine Lysine Methionine Cystine Phenylalanine Tyrosine Valine Arginine Histidine Alanine Aspartic acid Glutamic acid Glycine Proline Serine

3.55 3.77 6.51 5.47 1.09 2.06 4.54 2.71 5.13 10.5 2.66 4.35 10.3 18.8 6.11 4.04 5.17

3.71 3.93 6.92 5.84 1.41 2.73 4.62 2.70 5.23 9.91 2.47 4.63 10.2 17.6 6.09 4.45 5.84

3.47 3.96 6.35 5.88 1.33 2.61 4.46 2.85 5.19 11.00 2.73 4.31 10.1 18.4 6.01 4.08 5.20

3.72 4.23 7.11 6.18 1.42 2.66 4.71 2.87 5.19 9.63 2.62 4.69 10.3 17.1 5.92 4.52 5.19

Source: Bonafaccia, G. et al., Food Chem., 83, 1–5, 2003; Food Chem., 80, 9–15, 2003; Wei, Y. et al., Food/Nahrung, 47, 114–116, 2003.

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(Bonafaccia et al., 2003a, 2003b; Amudha Senthil, 2015). These are rich in lysine and arginine, which are limiting in true cereals whereas methionine and threonine are limited in buckwheat proteins. The major protein fractions of the buckwheat grain are water-soluble and salt-soluble albumins (21%) and globulins (12–13 subunits with molecular weights of 16–66 kDa) (Christa and Soral-Śmietana, 2008).

4.4.1.3 Lipids Buckwheat grain has about 3.25%–3.3% lipids with 2.5% free and about 1.3% bound lipids (dry matter) (Christa and Soral-Śmietana, 2008; Amudha Senthil, 2015). Triacylglycerides are the main components of lipids containing ten saturated fatty acids (FAs) (23.3% total FAs), and nine unsaturated fatty acids (76.7% total FAs) were identified with oleic acid (35.95% total FAs) as the most abundant fatty acid followed by linoleic acid (35.5% total FAs) and palmitic acid (16.99% total FAs) (Amudha Senthil, 2015).

4.4.1.4 Buckwheat Allergies With the increase in the consumption of buckwheat, increasing symptoms of allergies have been observed. Buckwheat allergy can cause severe reactions that are similar to those caused by soybean or peanut, and the reaction is an IgE-mediated immediate type reaction (Wijngaard and Arendt, 2006). Two major allergens isolated from buckwheat are the 16-kDa allergen, associated with strong pepsin resistance and IHR (immediate hypersensitivity reactions) including anaphylaxis in common buckwheat, and the 16-kDa allergen, associated with strong thermal stability and IgE binding activity in tartary buckwheat (Zheng et al., 2018).

4.4.2 Biologically Active Compounds in Buckwheat In comparison with quinoa, amaranth, and wheat, buckwheat-seed methanolic extracts have shown to have higher phenolic content (323.4mg GAE/100g), and antioxidant activity decreased in the order: buckwheat > quinoa > wheat > amaranth (Alvarez-Jubete et al., 2010). Concentration of total flavonoid is different in different parts of the buckwheat grain (i.e., seeds contain about 18.8  mg and hulls contain 74  mg per 100  g of dry weight) and the compounds isolated and identified in seeds are rutin and isovitexin, and hulls have rutin, orientin, vitexin, quercetin, isovitexin, and isoorientin (DietrychSzostak and Oleszek, 1999). Flavonoid and phenolic compounds found in the hull, bran, and flour of tartary buckwheat are rutin, p-hydroxybenzoic acid, ferulic acid, protocatechuic acid, p-coumaric acid, gallic acid, vallic and caffeic acid, syringic and chlorogenic acid (Guo et al., 2012), and in common buckwheat the compounds are protocatechuic acid, vanilic acid, syringic acid, ferulic acid, sinapic acid, rutin, and quercetin (Li et al., 2010). Rutin is the main flavonoid compound in both common and tartary buckwheat, and dehulled seeds of tartary contain traces of quercitrin and quercetin, which is absent in common buckwheat seeds. The antioxidant activity of common buckwheat (15.3–16.4 μmol-Trolox g−1 DW) is due to the presence of rutin (12.2–13.6 mg 100g−1 DW), epicatechin (15.6–20.2 mg 100g−1 DW), and epicatecingallate (1.3–2.4 mg 100g−1 DW), and

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the antioxidant activity of tartary buckwheat is mainly due to rutin (1808.7–1853.8 mg 100g−1  DW) and quercitrin (81.2–95.4 mg 100 g−1  DW), with an antioxidant activity of (52.9–57.4 μmol-Trolox g−1  DW) (Morishita et al., 2007). The tartary buckwheat grains also contain kaempferol-3-O-rutinoside (0.48–313.38 mg/100 g of flavonoid) and quercetin 3-O-rutinoside3′-O-β-glucopyranoside (0.23–248.76 mg/100 g of flavonoid) (Li et al., 2010). Phenolic and flavonoid content of both types of buckwheat in aerial parts were determined and found that the highest total phenolic content was in common buckwheat flowers collected at flowering and seed formation states (204 mg RE/g DW), and highest rutin content was observed in leaves (5.1%–8.2% DW) and flowers (7.2%–7.7% DW) collected from common and tartary buckwheat at early flowering (Zieliñska et al., 2012).

4.4.2.1 Rutin in Buckwheat Quercetin is known for its antioxidant activity and occurs naturally as glycoside in the form of rutin, a 3-O-beta-rhamnoglucoside form of quercetin (Yang et al., 2008). Rutin is a naturally occurring flavonoid in many foods, especially buckwheat, apricots, cherries, grapes, grapefruit, plums, and oranges. The chemical structure of rutin is shown in Figure 4.4. In the structure of quercetin, the double bond between carbons 2 and 3, and the hydroxyl group and the carbonyl group in the third ring on position C-3 and C-4, respectively, of the third ring are the key for flavonoids to exhibit antioxidant activity (Jiang et al., 2007; Yang et al., 2008). Also, hydroxyl groups on the first and second rings increase their antioxidant activities, and rutin and quercetin possess these structural features. The presence of significant antioxidant activity in rutin can have pharmacological applications (antimicrobial, antifungal, and antiallergic agents) (Gupta et al., 2014). An imbalance between reactive oxygen species (ROS) and antioxidant (compounds that act against the damaging effects of ROS) leads to

FIGURE 4.4 Structure of rutin. (From Jiang et al., Food Res. Int., 40, 356–364, 2007.)

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cellular damage by oxidative stress, which is linked to cancer, aging, atherosclerosis, ischemic injury, inflammation, and neurodegenerative diseases (Gupta et al., 2014). According to the findings of Zieliñska and Zieliñski (2009), in common buckwheat groats, the level of rutin is about 0.20 mg g−1  dry matter (mainly located in the hull) and that of tartary buckwheat groats is 80.94 mg g−1  dry matter (mainly located in the bran). Tartary buckwheat bran extracts showed the highest average total phenol content (TPC) (24.87  mg GAE g−1  DW), while common buckwheat hulls showed the highest reducing power and 2,2-diphenyl-1-picryl-hydrazylhydrate (DPPH) free radical scavenging activity with averages of EC50 84.54  g mL−1  and IC50 11.54  g mL−1, respectively, and common buckwheat flour showed the lowest TPC, reducing the power and radical scavenging activity (Li et al., 2013).

4.5 Health Benefits For about 1,000 years, buckwheat has been used in the treatment of many diseases as an effective medicinal herb in Chinese traditional therapy (Tömösközi and Langó 2017). Today, because of its beneficial nutritional properties and bioactive compounds, it is used as a raw material and additive in functional foods. Potr and Laskowski (2011) and Gao et al. (2016) have found that the starch granules of buckwheat are 10 times smaller than the starch granules of wheat and have a high amylose content (39.0%) and resistant starch with higher gelatinization temperature and enthalpy of gelatinization transition. Thus buckwheat starch has the potential for producing functional foods with retrograded starch and with a low glycemic index. Liu et al. (2017) have found that use of buckwheat flour in preparation of Chinese steamed bread have led to a reduced glycemic response. Also, the prebiotic properties are shown in the presence of resistant starch, which is not digested, and dietary fiber, which is available for fermentation by microflora. An increased proliferation of mesophilic and lactic acid bacteria, and a decrease of enterobacteria and pathogenic bacteria in female Wistar Hannover rats was found with a buckwheat diet (Préstamo et al., 2003). A compound called fagopyritols, a mono-, di-, and trigalactosyl derivatives of D-chiro-inositol found in buckwheat seeds, is an active substance that may be used in the treatment of diabetes and polycystic ovarian syndrome (Christa and Soral-Śmietana, 2008). Buckwheat is considered a well-balanced protein source, as it contains all 9 essential amino acids (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine), and also has low biological values above 90%. Lysine, an essential amino acid, is limited in cereal grains, thus buckwheat has a 0.56 g to 0.68 g (per 100 g of amino acid) lysine content, making it a complete protein source (Krumina-Zemture et al., 2016). The presence of a high ratio of unsaturated fatty acids, dietary fiber, protein content, and flavonoid and phenolic contents in buckwheat leads to many beneficial health effects. Some of the clinical trials and its beneficial health effects on animal models are listed in Table 4.2.

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Buckwheat TABLE 4.2 Health Benefits of Buckwheat Substances/Compounds

Action/Health Benefits

Plasma Cholesterol/Hypo-cholesterolemic Effects Buckwheat bran Reduction in total triglycerides (TG) and total cholesterol (TC), inhibition of lipid peroxidation in rat serum, increased antiatherosclerosis index, and reduce atherogenic index of plasma Buckwheat protein product Protein in buckwheat suppresses plasma cholesterol and gallstone formation (Tomotake et al., 2001) and the effect is mediated by higher fecal excretion of neutral sterols and that lower digestibility of protein Suggested that rutin was not responsible for lowering plasma cholesterol Prebiotic Dietary fiber and resistant Increased proliferation of mesophilic starch in cooked and lactic acid bacteria and decrease buckwheat of enterobacteria and less pathogenic bacteria in rats fed with buckwheat diet Immunology Buckwheat flour in Reduced impairment to intestine cause porridge, soup, and milk by celiac disease No toxicity (prolamines) for the celiac patient and no anti-protein antibodies formation in the grain Flavonoid (quercitrin) in Inhibition ofproliferation of buckwheat flour LPS-stimulated HaCaT keratinocytes and Th17 cell response regulated by the JAK/STAT signaling pathway, lowered the expression of cytokines related to psoriasis Antidiabetic Resistant starch and Reduced glycemic response amylose in buckwheat flour Anti-inflammatory Flavonoid and phenolic Inhibition of nitric oxide production content in fermented and preventing DNA damagebuckwheat induced disease and inflammation

References Wang et al. (2009)

Kayashita et al. (1997); Tomotake et al. (2001); Yang et al. (2014); Wang et al. (2017)

Préstamo et al. (2003)

De Francischi et al. (1994)

Chen et al. (2017)

Liu et al. (2017)

Huang et al. (2017) (Continued)

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TABLE 4.2 (Continued) Health Benefits of Buckwheat Substances/Compounds

Action/Health Benefits

References

Apoptosis Quercetin in seed and bran of buckwheat

Quercetin significantly led to arrest of the G2/M phase accompanied by an increase of apoptotic cell death after 48 h of incubation and a decrease of generation of reactive oxygen species in cells

Li et al. (2014)

4.6 Conclusion and Future Trends Buckwheat is rich in protein and dietary fiber, and its absence of prolamines (toxins) makes it a suitable ingredient for the development of functional food. It also has advantages in developing gluten-free products as it contains a high amount of amylose and resistant starch, thus reducing the glycemic index. Also, its proteins suppress plasma cholesterol and gallstone formation. Compounds present in bran raise the activity of serum glutathione peroxidase, which might reduce the total triglycerides and total cholesterol, thus inhibiting lipid peroxidation. The flavonoid and phenolic contents in buckwheat shows anti-inflammatory and antioxidant activity by preventing DNA damage that induces disease and psoriasis. Thus, buckwheat rich in biologically active compounds like rutin, quercetin, and epicatechin can be an alternative crop for the development of functional food products, which may reduce the prevalence of diabetes and celiac disease across the world. It can also act as an ingredient for commercial production of traditional food like crepes, soba-kiri, tarhana, etc. Fermented buckwheat is also another option for production of functional beverages as it is a good source of lactic acid bacteria.

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5 Maize Saraid Mora Rochín, Ada Keila Milán Noris, and Jorge Milán Carrillo CONTENTS 5.1 5.2

Introduction ...................................................................................................... 87 Processing Methods ......................................................................................... 89 5.2.1 Wet and Dry Milling ........................................................................... 89 5.2.2 Nixtamalization ................................................................................... 89 5.2.3 Extrusion..............................................................................................90 5.2.3.1 Lime-Cooking Extrusion .....................................................90 5.2.4 Other Processes ...................................................................................90 5.3 Product Development .......................................................................................90 5.4 Nutritional Values and Health Benefits............................................................ 92 5.5 Conclusion ........................................................................................................97 References ..................................................................................................................97

5.1 Introduction Cereals are the most important food for human nutrition. Wheat, maize, rice, and barley are the world’s four major agricultural cereal grains, with the first three comprising at least 75% of the world’s grain production (Hung, 2016). Cereals are grown on approximately 60% of the cultivated land in the world (Koehler and Wieser, 2013), and therefore provide 56% of the food energy and 50% of the protein consumed on Earth (Stoskopf, 1985). Maize (Zea mays L.), also known as corn, is a main cereal crop with agricultural and economic importance. In recent years, many researchers have developed novel strategies to enhance crop yield and resistance towards multiple biotic and abiotic stresses (Park et al., 2015). The history of maize domestication dates back to 8,700 years ago, in the area of present-day Mexico (van Heerwaarden et al., 2011; Piperno et al., 2009; Matsuoka et al., 2002). Subsequently, the progressive spread of the cultivated crop into the tropical regions and throughout the world in the following thousands of years (Lago et al., 2015) allowed hundreds of landraces and accessions to be adapted into different environments through human cultivation (Shen and Petolino, 2006). In the maize hybridization, several factors play an important role, such as temperature, photoperiod, humidity percentage, and altitude of the environment, which allowed the development and the differentiation of varieties and landraces. In addition, the farmers’ kernel selection, based on different quality features and cultivation, preserve the landraces as open 87

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pollinated populations creating a collection of maize plants with high heterozygosity and heterogeneity. This symbolized a very important source of variability and of alleles with high adaptation capacity to the local environments (Lago et al., 2015). However, in the last century, maize hybrids (as white grain) were widely grown in Mexico, the United States, and some European countries, displacing the traditional varieties. The new varieties from white maize (hybrids or genetically modified, such as transgenic maize) guaranteed nutritional improvement and superior productivity. According to botanical classification, maize kernel belongs to the monocot family Poaceae, and has similar agriculture to other cereals. This warm-season cereal is an annual plant and grows in tropical lowlands throughout the year in temperate climates during the frost-free season. Usually it is sown in springtime and matures in mid-summer. It requires more irrigation and has lower yields than winter cereals (Koehler and Wieser, 2013). Maize produces dry, one-seeded fruits, called a “kernel” or “grain,” in the form of a caryopsis, in which the fruit coat (pericarp) is strongly bound to the seed coat (testa). The kernel size and weight vary widely from big maize grains (≈ 350 mg) to small grains (≈ 9 mg). The anatomy of grain is uniform between varieties: fruit and seed coats (bran) enclose the germ and the endosperm, the latter consisting of the starchy endosperm and the aleurone cells (Koehler and Wieser, 2013). The grain structures and chemical composition caused notable differences among species and accessions. All these differences strongly affect the quality of products made from maize grains. A maize kernel is composed of endosperm (82%–83%), germ (10%–11%), pericarp (5%–6%), and tip cap (0.8%–1.0%). The pericarp is the outermost layer, which contains the crude fiber, mainly constituted of hemicellulose, cellulose, and lignin fragments. The hemicellulose fragment represents the highest concentration in the crude fiber. Pericarp thickness is different in each maize variety and extends to the base of the kernel joining the tip cap. Also, the pericarp and tip cap possess a negligible amount to total kernel lipids. The endosperm (approximately 82%–83% of grain kernel) is composed of a large number of cells; each packed with starch granules embedded in a continuous matrix of protein. The cell walls consist of non-starch polysaccharides (β-glucans and arabinoxylan), proteins, and phenolic acids. Maize grain has two types of endosperm: floury endosperm (loosely packed starch granules surrounding the central fissure) and horny endosperm (tightly packed, smaller starch granules towards the periphery) (Singh et al., 2011). Protein bodies are composed mostly of a prolamine-rich protein fraction known as zein, which is deficient in lysine. At least four major fractions have been identified within the zein storage protein: α-zein (21–25 kDa), β-zein (17–18 kDa), γ-zein (27–28 kDa), and δ-zein (9–10 kDa). However, the individual zein vary in composition and concentration based on the maize genotype (Esen, 1987). Starch is the main component of a maize kernel and varies with genotypes and agriculture practices. The amylose content of corn starches from five cultivars varied from 24.74 to 30.32 g/100 g (Mir et al., 2017). The size of a starch granule in maize grain ranges between 1–7 μm (small granule) and 15–20 μm (large granule). Maize starches exhibit a typical A-type pattern, in which double helices comprising the crystallites are densely packed. Sugary maize starch has lower crystallinity, while waxy maize starch has greater crystallinity as compared to normal maize starches. The sugary maize starch has lower gelatinization temperature and enthalpy. The maize starch with long-branch chain length amylopectin and higher crystallinity has higher gelatinization temperature and enthalpy (Singh et al., 2014).

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5.2 Processing Methods 5.2.1 Wet and Dry Milling Industrial processing of maize is categorized in two main processes: wet and dry milling. Wet milling is used to separate the constituents of maize (starch, oil, protein, and fiber). The maize is soaked (steeped) in water with sulphur dioxide to soften the kernel. Then, softened kernels are ground and the components separated to yield germ fractions that contain the oil, to further isolate the oil. Some of the product generated by wet milling includes cornstarch, sweeteners, ethanol, and alcoholic beverages (Johnson and May, 2003). Dry milling of maize is used to generate products for human consumption or fuel (ethanol production), and remaining products for animal feed (Hammond and Jez, 2011). This milling is performed on cleaned whole maize or previously degermed maize. The degermination process eliminates the germ with a high content of oil and generates more shelf-stable flours (Gwirtz and Garcia-Casal, 2014). The maize is ground with millstones and the product is called corn meal. Also, flour from germinated maize grains has many food applications in the United States, such as ready to eat (RTE), breakfast foods, snacks, pancakes, doughnuts, muffins, breads, and batters, and also as binders in processed meats and other foods (Hammond and Jez, 2011).

5.2.2 Nixtamalization The traditional nixtamalization process was developed by the Mesoamerican cultures. This process involves a thermo-alkaline treatment, where maize kernels are cooked and steeped in an oversaturated calcium hydroxide solution (Gutiérrez et  al., 2007; Bello-Pérez et  al., 2015). A specific characteristic of the traditional nixtamalization process is the long soaking time (12–16  h) and generates large liquid-waste discharges (3–10 L of contaminated effluents/kg of maize) (CortésGomez et al., 2006; Eckhoff et al., 2010). Traditional nixtamalization also carries a high-energy cost due to the low efficiency of heat transfer. All these factors have important economic and commercial implications (Aguayo-Rojas et  al., 2012). During the alkaline cooking, there is a calcium concentration gradient through the pericarp structure of the maize kernel. This promotes physicochemical changes in the germ and endosperm, and in the internal anatomical structures of maize kernel. These changes modify the kernel structure and the rheological properties as a result of a heat and mass transference phenomenon (Gutiérrez-Cortez et al., 2010). Moreover, the total removal of the pericarp during the nixtamalization process causes nixtamalized products to require additives to improve their mechanical properties; for example, flexibility and texture of tortillas (Martínez et al., 2001; Gutiérrez-Cortez et al., 2010). However, the pericarp is one of the most important sources of dietary fiber required for proper human digestion of cereals (SernaSaldívar, 1996). For this reason, it is important to keep in mind that processing of maize requires finding optimized conditions to avoid the partial loss of the pericarp and other anatomical parts, as well as the leaching of the other biomolecules, such as protein, vitamins, minerals, and phenolic compounds, to the cooking liquid.

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5.2.3 Extrusion Extrusion cooking is one of the most important food processing methods. This process has been used since the mid-1930s for the production of breakfast cereals, ready to eat snack foods, and other textured foods. Furthermore, the extrusion-cooking process has become the main processing technology for cereals and feed industries, and it is rapidly evolving from an art into science and technology (Riaz et al., 2009). This food processing technology is preferred over others as it is a high temperature short time (HTST) process, which maintains important nutrients, reduces anti-nutritional components of foods (trypsin inhibitors, tannins, and phytates), disinfects the final product, and conserves normal colors and flavors of the food (Guy, 2001; Gbenyi et al., 2016).

5.2.3.1 Lime-Cooking Extrusion Lime-cooking extrusion produces instant flours suitable for tortillas with similar characteristics to their counterparts produced using the traditional nixtamalization process (Milán-Carrillo et al., 2006). Prior to the extrusion process, maize grains are prepared in order to obtain nixtamalized/extruded flours for tortilla-making. Briefly, maize grains are ground to obtain grits that pass through a 10 US mesh (2 mm) screen, and mixed with lime (0.21 g of Ca[OH]2/100 g of maize), then conditioned with distilled water until the moisture content reaches 28% (w/w), and is then stored for 12 h at 4°C (Milán-Carrillo et al., 2006). Lime-cooking extrusion offers the advantage of not generating wastewater or cooking liquid (nejayote) (Aguayo-Rojas et al., 2012), and the products generated can be considered whole grain foods since the process avoids the leaching of nutrients during the soaking step in the traditional process.

5.2.4 Other Processes The maize flour, cornstarch or nixtamalized flours are usually processed further into different products. The processes employed are drying, boiling, baking, or frying to produce different products (Gwirtz and Garcia-Casal, 2014). Moreover, the production of some traditional maize food involves the process of fermentation from corn flour, nixtamalized flour, or whole grains (Hammond and Jez, 2011).

5.3 Product Development Since ancient times, maize has been a staple food worldwide and the main ingredient in Latin American cuisine. The maize kernel is consumed at different maturity stages, such as baby corn (as a vegetable), immature maize, and mature maize (Serepoua et al., 2015). Moreover, its demand is increasing because of its use for biofuel production (Singh et  al., 2014). Also maize wet-milling allows for the fragmentation into starch and corn oil, and for the production of sweeteners (Johnson and May, 2003). Mexico has a great dependence on maize and close to 75% of its consumption is in the form of tortillas, which constitute the staple of the Mexican population (GutiérrezCortez et al., 2010). Besides tortillas, there are many traditional foods that are made

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with nixtamalized dough or flour, such as tacos, tostadas, enchiladas, etc. The dough can be mixed with other ingredients and wrapped in corn/banana leaves and steamed to obtain tamales. Also, nixtamalized dough can be wrapped in banana leaves and fermented for 1–14 days and mixed with cocoa and milk to create a beverage called Pozol (Rooney and Serna-Saldivar, 2003). Nowadays, demand of nixtamalized products of blue maize has increased due to its distinctive flavor and color with potential health benefits, and is consumed as totopos (Urias-Peraldí et al., 2013; Mora-Rochín et al., 2016). Table 5.1 shows the various maize products consumed globally. A very popular maize food in South America (Venezuela and Columbia) is arepa. This is prepared with precooked refined flour and further fried or baked (Gwirtz and Garcia-Casal, 2014). Several fermented foods from African countries are usually produced (Table 5.1) as ogi, which are prepared by soaking the maize kernels for 1–3 days to soften, then ground, dehulled, and degermed, then repeatedly washed. The endosperm is fermented for 2–3 days. The slurry is boiled to produce ogi or uji, depending on the African region (Gwirtz and Garcia-Casal, 2014; Ekpa et al., 2018). TABLE 5.1 Various Maize Products Consumed Globally Category Whole grains

Snacks Bread Unfermented Porridges Fermented Unfermented Beverages Nonalcoholic

Alcoholic

Steamed food

Regional Food Type (Country) Pozole (Mexico), hominy (US), adalu, egbo (Nigeria), githeri, muthokoi (Kenya), aboda (Benin), ayibli, nkyekyerewa, adibabli (Ghana), kandy, mandake (Tanzania), mangai, matakura (Zimbabwe), lisontfwana, tinhlumayanemphuphu (Swaziland), setampo (Lesotho), umngqusho, samp (South Africa), corn tchap (Cameroon), roasted and boiled maize (Africa) Popcorn, corn on the cob (worldwide), totopos, tostadas (Central and North America), donkwa (Nigeria) Muufo (Somalia), tortillas, tacos (Central and North America), arepas, empanadas (Venezuela, Colombia), roti (India), corn bread (worldwide) Ogi (Nigeria), uji, ugali (East Africa), mahewu (South Africa) Atole, pinole (Mexico, Central America), Mingau, canjicamunguca, pamonha (Brazil) Kunnu zaki (Nigeria), akpan (Benin), mahewu (South Africa), munkoyo (Zambia, Zaire), togwa (Tanzania), kunnu zaki (Nigeria), kirario (Kenya), borde (Ethiopia), pozol (Mexico), chichamorada (South and Central America) Chicha, corn beer (South and Central America), umqombothi, kafir beer (South Africa), obiolo, pito (Nigeria), busaa, chang’aa, busas (Kenya), pombe, chibuku (Zambia), cheka, talla (Ethiopia), chikokivana, kachasu, doro (Zimbanwe), malawa, kidongo (Uganda), tesguino (Mexico), burokuto (Nigeria), opaque beer, munkoyo (Zambia) Tamales (Latin America), couscous (Africa, Brazil), corn dumplings (Africa)

Source: Hammond, B.G., and Jez, J.M., Food Chem. Toxicol., 49, 711–721, 2011; Rooney, L.W., and Serna-Saldivar, S.O., Food use of whole corn and dry-milled fractions, in: While, P.J., and Johnson, L.A. (Eds.), Corn Chemistry and Technology, 2nd ed., American Association of Cereal Chemists, St. Paul, MN, pp. 495–535 (Chapter 13), 2003; Ekpa, O. et  al., Global Food Security, 17, 48–56, 2018.

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5.4 Nutritional Values and Health Benefits Maize grain (~11%–14% moisture content) contains a high content of carbohydrates. Besides carbohydrates, proteins, and lipids, the maize grains are a good source of vitamins and minerals with nutritional relevance (Koehler and Wieser, 2013). Table 5.2 shows the average nutritional composition of a maize kernel. The starch is the main carbohydrate in maize (56%–74%) and is contained in the endosperm, and the fiber (2%–13%) is present in the bran. Carbohydrates such as starch and dietary fiber (insoluble and soluble) have an important effect on human health. The rate of digestion and absorption of carbohydrates can be a determinant for the metabolic control of some chronic noninfectious diseases (Jenkins et  al., 2002). Many reports have indicated the role of dietary fiber in lowering postprandial serum glucose, and the main mechanism was regarded as the viscosity of different components of dietary fibers in impeding diffusion of glucose and postponing absorption and digestion of carbohydrates (Ou et  al., 2001). For this reason, there has been a growing interest in the consumption of maize and their products, which are considered a good source of starch and dietary fiber (BelloPérez et al., 2014). In México, the maize is highly consumed in the form of tortillas and other products (snacks, tostadas, tamales) made with nixtamalized flours. The traditional nixtamalization process for maize generates an important amount of glycemic carbohydrates (Bello-Pérez et  al., 2014). However, it is interesting to note that digestive enzymes do not hydrolyze completely all the starch content in tortillas, and other amounts of TABLE 5.2 Nutritional Composition of Maize Grain (Average Values) Parameter Moisture Protein (N × 6.25) Lipids Bioavailable carbohydrates Fiber Minerals

Content (g/100 g) 11.3 8.8 3.8 65 9.8 1.3 (mg/100 g)

Folic acid Total tocopherols Thiamine (Vitamin B1) Riboflavin (Vitamin B2) Nicotinamide Panthothenic acid Piridoxine (Vitamin B6)

0.03 6.6 0.36 0.2 1.5. 0.65 0.40

Source: Belitz, H. D. et al., Cereals and cereal products, in: Belitz H. D. et  al. (Eds.), Food Chemistry, Springer-Verlag, Berlin, Germany, 2009; Koehler, P., and Wieser, H., Chemistry of cereal grains, in: Handbook on Sourdough Biotechnology, Springer, New York, pp. 11–45, 2013.

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starch are slowly hydrolyzed (Aparicio-Saguilan et al., 2013; Bello-Pérez et al., 2014). The tortilla storage caused by the retrogradation of starch decreased starch digestion by increasing the resistant starch part. Studies have shown that tortillas have a high glycemic index, but slowly digestible starches (Lee et al., 2013). Moreover, tortillas and others products elaborated with nixtamalized maize are important sources of total dietary fiber content (higher insoluble dietary fiber than soluble dietary fiber), indicating that these products are a good source of insoluble dietary fiber or indigestible carbohydrates. Interestingly, a high insoluble dietary fiber is important because of its bulking properties and the more rapid transit through the stomach and intestine (Ou et al., 2001; Bello-Pérez et al., 2014). Maize products (canned, frozen, and boiled sweet corn) have a lower glycemic index (GI) than white rice and wheat flour bread. Waxy maize starch is more rapidly digested and has a higher GI than high-amylose starches (Singh et  al., 2014). Moreover, the long storage times of maize grain could change some nutritional aspects such as solubility and digestibility of proteins and increased free fatty acids, and these may form complexes with amylose or amylopectin short chains, modifying the nutritional properties and the physical characteristics of the final products (TadeuParaginski et al., 2014). Maize has an average protein content of 8%–11%, and is well known for the low quality of protein. Most of the protein in a mature maize kernel is present in the endosperm and the germ fraction. The endosperm protein is low in quality, in comparison with the germ protein. However, because the endosperm constitutes the bulk of the grain, contributing as much as 80% of the total kernel protein, any major improvements for quality protein must target the endosperm. In normal maize, the main fraction is formed by zein, which lacks two important essential amino acids, lysine and tryptophan (Milán-Carrillo et al., 2006). The high proportion of this particular fraction is the primary cause of low protein quality in maize (Vasal, 2000). Since the mid-1960s, several methods have been developed to increase the protein quality in maize. One of these approaches was to produce transgenic maize with the expression of the protein of amaranth (amaranthin); the kernel of the transgenic maize has increments in total protein (+32%) and the essential amino acids such as lysine (+18%), isoleucine (+36%), and tryptophan (+22%) (Ayala-Rodríguez et  al., 2009). Also, researchers from the International maize and wheat improvement center (CIMMYT) produced quality protein maize (QPM). The effects of the two mutant alleles, Opaque-2 and Floury-2, alter the amino acid profile and composition of the endosperm maize protein, which increased twofold the levels of lysine and tryptophan. The CIMMYT has used these mutants, and others, in the development of QPM germplasm, producing maize with good agronomic performance and market acceptability (Vasal, 2000). Tortillas are a staple food in the Mexican diet, and in a high portion of the population, they are the main source of energy and nutrients. Although there are nutritional losses during the traditional process, nixtamalized products such as tortillas maintain average values in their proximal composition (Table 5.3). In contrast, lime-cooking products are considered whole grain foods because of the nutritional composition. Also, whole grain consumption has been associated with the reduction in the risk of cardiovascular disease (CVD), type 2 diabetes, and some cancers (Serna-Saldivar, 2010).

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Content (%, db) TN TE

Protein Lipid Minerals Bioavailable carbohydrates Total dietary fiber Total starch Resistant starch

10.9 6.54 1.63 80.0 10.1 62.6 1.7

13.1 4.8 1.7 67.5 12.9 61.9 1.3

Thiamin Riboflavin Niacin Folic acid

(mg/100 g) 0.06 0.08 2.46 0.017

– – – –

Source: Burton, K.E. et  al., Cereal Chem., 85, 70–75, 2008; Gutiérrez-Dorado, R. et  al., Cereal Chem., 85, 808–816, 2008; Ayala-Rodríguez, A.E. et  al., Food Chem., 114, 50–56, 2009; Reyes-Moreno, C. et al., J. Cereal Sci., 58, 465–471, 2013; Bello-Pérez, L.A. et al., Cereal Chem., 92, 265–270, 2015. TN: Tortilla nixtamalized; TE: Tortilla extruded; (–): Not detected.

Bioactive compounds, such as phenolic acids and flavonoids, in our diet may provide potential health benefits (Manach et al., 2005; Hung, 2016). These health benefits from the intake of natural bioactive compounds have been attributed to their antioxidant capacity, which can protect against degenerative diseases such as some types of cancers, diabetes, and cardiovascular diseases (Heim et al., 2002; Williams and Spencer, 2012; Dasgupta and Klein, 2014; Hung, 2016; Xiao et al., 2016). White and pigmented maize, like fruits and vegetables, contain various bioactive constituents that are a good source of natural antioxidants with strong free radical scavenging activity, which are associated with health promotion and disease prevention properties. These compounds include carotenoids, anthocyanins, and phenolic compounds that vary among maize genotype. Table 5.4 depicts the content of bioactive compounds and antioxidant activity in different maize genotypes. Phenolic acids and flavonoids are the most common types of phenolic compounds found in whole maize kernels and may be present in different forms, such as soluble free and conjugated or insoluble bound form (Mora-Rochín et al., 2010; Zilic et al., 2012; Sarepoua et al., 2015; Gaxiola-Cuevas et al., 2017). The bound form contributes more than 80% of the phenolic content, and this fraction is responsible for the antioxidant capacity in maize grain (Adom and Liu, 2002). Also, maize showed a higher antioxidant activity (157.68  μmol/g) compared to wheat (68.74  μmol/g), oats (43.60  μmol/g), and rice (39.76  μmol/g) (Adom and Liu, 2002). Phenolic acids are derivatives of benzoic and cinnamic acids, found in cereals (Dykes and Rooney, 2007). The most common hydroxycinnamic acids are caffeic,

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Antioxidant Activityd

Genotype

Free

Bound

Total

Anthocyaninsb

Carotenoidsc

Hydrophilic

Lipophilic

White Yellow Red Blue

37.9 19.8 36.3 33.8

121.1 106.5 116.1 113.2

159.0 126.3 152.4 147.0

0.92 0.96 0.81 27.5

– 4.75 2.04 –

23,450 21,900 24,900 22,500

– 26,070 23,250 –

Source: Aguayo-Rojas, J. et  al., Plant Foods Hum. Nutr., 67, 178–185, 2012; Corrales-Bañuelos, A.B. et al., J. Cereal Sci., 69, 64–70, 2016. a mg Equivalents of Galic Acid (EGA)/100 g, dw; b mg Equivalents of Cyanidin-3-glucoside/100 g, dw; c mg Equivalents of Lutein/100 g, dw; d  μmol Equivalents of Trolox/100 g, dw; (–) Not detected. Genotype accessions of different maize: White (Bolita); Yellow (Tuxpeño); Red (Tabloncillo and Chapalote); Blue (Elotero de Sinaloa).

p-coumaric, and ferulic acids, which frequently are found in maize as simple esters with quinic acid or glucose (Hung, 2016). The main phenolic compound found in maize grain is ferulic acid and is concentrated in the pericarp in bound form or esterified to the heteroxylanes that make up the hemicelluloses of the cell wall. This bioactive compound represents more than 80% of the total phenolic content in the bound form and provides more than 90% of the total antioxidant activity. Ferulic acid can readily form a resonance stabilized phenoxyl radical, which accounts for its potent antioxidant potential (Adom y Liu, 2002; De la Parra et al., 2007; Gaxiola-Cuevas et al., 2017). Thermal processing has a meaningful role in the release of free ferulic acid that is responsible for an increase on antioxidant activity in maize products. Some processes such as nixtamalization, tortilla baking, and tortilla chip frying increase the amount of free and soluble conjugated ferulic acid (De la Parra et  al., 2007; Mora-Rochín et  al., 2010; Gaxiola-Cuevas et  al., 2017). Recently, ferulic acid has been used as a supplement that claims to slow the aging process (Singh et al., 2011). Anthocyanins are a type of flavonoids and water-soluble glycosides of polyhydroxy and polymethoxyderivates of 2-phenylbenzopyrylium or flavylium salts that are potent natural antioxidants due to their ability to trap free radicals. These bioactive compounds are responsible for the red, purple, and blue colors of many fruits, vegetables, and some maize genotypes. The pigments are derived from the simple or acylated anthocyanin located in the aleurone cell or pericarp of the maize endosperm, which affect the color of the kernel. These pigments can be separated for multiple uses, such as into anthocyanin-rich fractions to be used as functional colorants or functional food ingredients, due to their beneficial health effects (Giusti and Wrolstad, 2003; Betran et al., 2000; Zilic et al., 2012; Rodríguez-Méndez et al., 2013). In a blue maize kernel, the anthocyanins present are cyanidin and malvidin, whereas in a red maize kernel there are pelargonidin, cyanidin, and malvidin. The anthocyanin biosynthesis pathway in maize is influenced by at least two regulatory genes, R1/B1  and C1/Pl1  family, in which the presence a least one of each family

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and their interaction allows the initiation of the nearly 20 structural genes necessary for anthocyanin coloration production for the tissue specific coloration of plant and seed tissues (Lago et al., 2015). Mora-Rochin et al. (2016) studied anthocyanins in fifteen blue maize accessions and reported that the most abundant anthocyanins are the acyl type, as cyaniding-3-(6″-succinylglucoside) (Cy-Suc-Glu) and cyaniding-3(6″-disuccinylglucoside) (Cy-diSuc-Glu), representing for 52.1% and 15.6% of the total anthocyanins. Other major anthocyanins found were cyaniding-3-glucoside (Cy-3Glu), pelargonidin-3-glucoside (Pg-3-Glu), pelargonidin-3-(6″-malonylglucoside) (Pg-Mal-Glu), and cyaniding-3-(6″-malonylglucoside) (Cy-Mal-Glu). Moreover, the chemical structure of the anthocyanin determines its stability, color intensity, and potential biological activity. Anthocyanin stability has been attributed to intramolecular and/or intermolecular copigmentation and self-association reactions. The monomeric anthocyanins are affected by factors such as hydration, alkaline pH, high temperature, and light exposure. Therefore, sources of acylated anthocyanins may provide the desirable stability for food applications (Dangles et al., 1993; Giusti and Wrolstad, 2003). Carotenoids are other important bioactive compounds present in maize and are related to yellow pigmentation. These biomolecules are hydrophobic C40 isoprenoids and are synthesized in amyloplasts (Lago et al., 2015). Commonly, carotenoids are classified in two classes: (1) carotenes or carotenoid hydrocarbons, composed of only carbon and hydrogen as β-carotene and lycopene; and (2) xanthophylls or oxygenated carotenoids, which contain a hydroxyl functional group as lutein and zeaxanthin (Prabhashankar-Arathi et  al., 2015). The most important carotenoids in the human diet are β-carotene, α-carotene, lycopene, lutein, zeaxanthin, and β-cryptoxanthin (Khachik, 2006). In some developing countries, white maize is mainly used in human diet, but it is known that Vitamin A, derived from carotenoids (absent in white maize), is essential for human health, leading to a worldwide vitamin A deficiency (Lago et al., 2015). Furthermore, in yellow maize, carotenoids biosynthesis that has been related to more than 30 loci and main types of mutations are the ys, which reduce or deplete carotenoids, giving white or pale yellow endosperm (Chander et al., 2008). Lutein and zeaxanthin are the major carotenoids in yellow maize. Also, α and β-cryptoxanthin and α- and β-carotene have been reported in minor concentration. Corrales-Bañuelos et al. (2016) evaluated 8 Mexican pigmented types of maize (yellow and red), in which lutein and zeaxanthin were the main carotenoids, accounting for ~85% of total carotenoids. Moreover, a correlation among the antioxidant activity of lipophilic fraction and carotenoid content was found (Table 5.4). The presence of lutein in other sources has been related to antitumorpromoting activity and suppression of tumor growth in mice (Park et al., 1998), and the prevention of age-related macular degeneration, which causes early blindness (Prabhashankar-Arathi et al., 2015). The processing effect on carotenoid content is difficult to evaluate because some carotenoid molecules are transformed to other isomers or degraded. The carotenoids are affected by high temperature, light, air, and pH changes; however, lutein has demonstrated better heat stability. White maize has lower antioxidant activity due to lower amounts of anthocyanins and carotenoids. The utilization of yellow and pigmented maize instead of white maize can provide nutritionally better products. However, in many industrially manufactured products, white corn is preferred (e.g., nixtamalized products) (Singh et  al., 2011, CorralesBañuelos et al., 2016).

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5.5 Conclusion Maize contributes an important part of human diet worldwide. In developing countries, maize is the main source of energy and nutrients, thus maize is a good candidate for nutrient fortification programs. Despite the good protein quality genotypes, maize breeding programs have mainly focused on the development of high-yielding varieties, leading to a progressive destruction of genetic diversity, including the one responsible for the kernel pigment variation and an important source of bioactive compounds. The evidence provided herein supports that pigmented maize contains high levels of bioactive compounds compared with other cereals and could be considered for the commercial production of maize-based foods.

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Pineda-Hidalgo, K. V., Méndez-Marroquín, K. P., Vega-Alvarez, E., Chávez-Ontiveros, J., Sánchez-Peña, P., Garzón-Tiznado, J. A., Vega-García, M. O., López-Valenzuela, J. A. 2013. Microsatellite-based genetic diversity among accessions of maize landraces from Sinaloa in México. Hereditas 150:53–59. Prabhashankar-Arathi, B., Raghavendra-Rao, P., Sowmya, Vijay, K., Baskaran, V., Lakshminarayana, R. 2015. Metabolomics of carotenoids: The challenges and prospect. Trends in Food Science and Technology 45:105–117. Reyes-Moreno, C., Ayala-Rodríguez, A. E., Milán-Carrillo, J., Mora-Rochín, S., LópezValenzuela, J. A., Valdez-Ortiz, A., Paredes-López, O., Gutiérrez-Dorado, R. 2013. Production of nixtamalized flour and tortillas from amarantin transgenic maize limecooked in a thermoplastic extruder. Journal of Cereal Science 58:465–471. Riaz, M. N., Asif, M., Ali, R. 2009. Stability of vitamins during extrusion. Critical Reviews in Food Science and Nutrition 49:361–368. Rodríguez-Méndez, L. I., Figueroa-Cárdenas, J. D., Ramos-Gómez, M., Méndez-Lagunas, L. T. 2013. Nutraceutical properties of flour and tortillas made with an ecological nixtamalization process. Journal of Food Science 78:C1529–C1534. Rooney, L. W., and Serna-Saldivar, S. O. 2003. Food use of whole corn and dry-milled fractions. In: While, P. J., and Johnson, L. A. (Eds.), Corn Chemistry and Technology, 2n ed. American Association of Cereal Chemists, St. Paul, MN, pp. 495–535 (Chapter 13). Sánchez, J. J., and Goodman, M. M. 1992. Relationships among Mexican races of maize. Economic Botany 46:72–85. Sánchez, J. J., Goodman, M. M., Stuber, C. W. 2000. Isozymatic and morphological diversity in the races of maize of México. Economic Botany 54:43–59. Sánchez-Madrigal, M. A., Quintero-Ramos, A., Martínez-Bustos, F., Meléndez-Pizarro, C. O., Ruiz-Gutiérrez, M. G., Camacho-Dávila, A., Torres-Chávez, P. I., RamírezWong, B. 2015. Effect of different calcium sources on the bioactive compounds stability of extruded and nixtamalized blue maize flours. Journal of Food Science and Technology 52:2701–2710. Sarepoua, E., Tangwongchai, Suriharn, B., Lertrat, K. 2015. Influence of variety and harvest maturity on phytochemical content in corn silk. Food Chemistry169:424–429. Serna-Saldívar, S. O. 1996. Química, Almacenamiento e Industrialización de los cereals, 1st ed. AGT, México. Serna-Saldívar, S. O. 2010. Cereal Grains: Properties, Processing and Nutritional Attributes. CRC Press (Taylor & Francis Group), Boca Raton, FL. Shen, L. Y., and Petolino, J. F. 2006. Pigmented maize seed via tissue-specific expression of anthocyanin pathway gene transcription factors. Molecular Breeding 18:57–67. Singh, N., Kaur, A., Shevkani, K. 2014. Maize: grain structure, composition, milling, and starch characteristics. In: Chaudhary, D. P. (Ed.), Maize: Nutrition Dynamics and Novel Uses. Springer, New Delhi, India, pp. 65–76. Singh, N., Singh, S., Shevkani, K. 2011. Bioactive constituents, and unleavened bread. In: Preedy, V. R., Watson, R. R., and Patel, V. B. (Eds.), Flour and Breads and Their Fortification in Health and Disease Prevention. Elsevier, London, UK, pp. 89–99. Stoskopf, N. C. 1985. Cereal Grain Crops. Reston Publishing, Reston, VA. Tadeu-Paraginski, R., Levien-Vanier, N., Moomand, K., de Oliveira, M., da RosaZavareze, E., Marques e Silva, R., Dietrich-Ferreira, C., Cardoso-Elias, M. 2014. Characteristics of starch isolated from maize as a function of grain storage temperature. Carbohydrate Polymers 102:88–94.

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6 Millets Sudha Rani Ramakrishnan, Kavitha Ravichandran, and Usha Antony CONTENTS 6.1 6.2

Introduction .................................................................................................... 103 Millet Processing ........................................................................................... 105 6.2.1 Milling ............................................................................................... 105 6.2.2 Popping and Puffing .......................................................................... 106 6.2.3 Grits and Flour .................................................................................. 107 6.2.4 Germination....................................................................................... 107 6.2.5 Fermentation ...................................................................................... 108 6.2.6 Extrusion............................................................................................ 110 6.3 Traditional and Novel Millet Products........................................................... 111 6.3.1 Ethnic Fermented Foods of Asia ....................................................... 113 6.3.1.1 Jnard .................................................................................. 113 6.3.1.2 Koozh ................................................................................. 113 6.3.2 Ethnic Fermented Foods of Africa .................................................... 114 6.3.2.1 Borde .................................................................................. 114 6.3.3 Ethnic Alcoholic Beverages of Asia.................................................. 115 6.3.3.1 Kodo Ko Jaanr ................................................................... 115 6.3.3.2 Madua ................................................................................ 115 6.3.3.3 Themsing ............................................................................ 116 6.3.3.4 Rakshi................................................................................. 117 6.3.4 Novel Millet Products........................................................................ 117 6.4 Nutritional and Health Benefits ..................................................................... 119 6.4.1 Other Functional/Bioactive Components .......................................... 120 6.5 Conclusion ...................................................................................................... 122 References ................................................................................................................ 122

6.1 Introduction Millets are seeds of grasses that belong to Poaceae family of the monocotyledon group. Compared to other major cereals, the grains are very small in size, with their thousand kernel weight being 2–7  g and volume 1.4–5.0  mL, while their density ranges from 1.34 to 1.42 g/mL. They are spherical or oval in shape and often possess colored seed coats.

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Millets are known as the first domesticated cereals that were cultivated for at least 10,000 years in East Asia. For centuries, millets have served as an important staple in parts of Asia and Africa and are widely grown around the world as cereal and grain crops for both food and feed use. Millets are sixth place in world cereal production. World production is estimated to be 29,870,058 tonnes (“India leads the world in millet production,” 2017). India has the highest demand for millet seeds and is the largest millet producer globally (40%), followed by Nigeria, Niger, and China. Millets are important crops in the semiarid tropical regions and have several ecoadvantages: most drought resistant of all cereal grains; can survive in areas with 300 mm or less rainfall per year; are adaptable to diverse climatic conditions; tolerate varying levels of soil fertility; and have short growing periods. Most millets also have excellent storage properties and can be kept for up to 4–5 years even in simple storage facilities, such as traditional granaries, and seeds are protected from insect attack by the hard hull covering the endosperm (“The millet seed,” https://www.usaemergencysupply.com). There are more than 6,000  millet varieties around the world, and their colors show wide variation ranging from white to pale yellow or red, and can even be gray. Pearl millet (Pennisetum glaucum) is the most cultivated millet, grown predominantly in India and parts of Africa. Other major millet seed varieties are finger millet (Eleusine coracana), proso millet (Panicum miliaceum), and foxtail millet (Setaria italica). Other minor millets include little millet (Panicum sumatrense), kodo millet (Paspalum scrobiculatum), Indian barnyard millet (Echinochloa frumentacea), and barnyard millet (Echinochloa crusgalli). Figure 6.1 shows some of the millets grown in different countries. The six different species of millets cultivated by farmers in India are: little millet (Panicum sumatrense Roth ex Roem. & Schult.), proso millet (Panicum miliaceum L.), Italian millet (Setaria italica (L.) P. Beauv.), kodo millet (Paspalum scrobiculatum L.), Indian barnyard millet (Echinochloa frumentacea L.), and finger millet (Eleusine coracana (L.) Gaertn.) (Newmaster et al., 2013).

FIGURE 6.1 Types of millets crops.

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The per capita consumption of millets is the highest in the countries of Western Africa. In the Sahel region countries of Gambia, Burkina Faso, and Chad, 35% of the total cereal consumption contained millet. In Niger and Namibia, 60% of the cereal consumption involves millets, while the cereal accounts for 40% of the cereal intake in Mali and Senegal (“India leads the world in millet production,” 2017). This chapter highlights the traditional and more recent methods of processing these miniscule grains and their nutrient contribution and health benefits, which remain underutilized. The potential of millets in the context of climate change, land use, agronomic inputs required, sustainability, and the double burden of undernutrition and chronic degenerative diseases are indeed great and the additional efforts required in this direction need to be underscored.

6.2 Millet Processing Processing methods are necessary for improving the nutritional availability and storage stability of flour as well as the products. Therefore, for encouraging the commercial utilization of millet grains in food formulations and to achieve better food security, it is necessary to use appropriate processing methods. Millets, like other cereals, are covered with hulls, which need to be removed. Processing of millets involves partial separation of germ, endosperm, and pericarp or bran. Although traditional methods are widely used, they seem to be laborious, monotonous, and mostly done by hand. Traditional processing methods include decortication, malting, fermentation, roasting, flaking, and grinding to improve their edible, nutritional, and sensory properties. Modern processing methods for millets are still in development when compared to wheat and rice processing (Dayakar Rao et al., 2017).

6.2.1 Milling The structure of a finger millet grain shows that the utricle consists of a five-layered testa, called the pericarp (P) that varies from red to purple in color, the endosperm, and the embryo (EM) (Figure 6.2). The aleurone layer (A) is beneath the testa and one cell layer thick. The starchy endosperm containing amyloplasts (AM) has distinct peripheral, corneous, and floury areas. Starch granules are primarily compound with some simple granules in the corneous area. Starch granules’ size increases towards the center of the endosperm, while the protein content decreases. The outer layer of the testa and the cell walls of the endosperm strongly fluoresce under fluorescence microscopy, indicating phenolic compounds (Figure 6.2). The small germ (EM) is inset into a shallow depression; a short ridge protrudes from the utricle around the perimeter of the germ (Antony, 1997). Data on the microstructure of other millets is negligible. Due to their miniscule size, traditional milling of millets has been through hand pounding to remove the seed coat. More recently, milling machines have been developed. Milling of pearl millet and finger millet is difficult because of their small kernel with a firmly embedded germ attached to a hard endosperm and the tightly bound seed coat. These are usually consumed/processed whole without the removal of the seed coat. In other millets, such as foxtail millet and barnyard millet, where the seed coat is hard and thick, milling is done to remove the seed coats and often polished in

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FIGURE 6.2 Microstructure of finger millet. P—Pericarp; EM—Embryo; A—Aleurone layer; AM—Amyloplast. (From Antony, U., Nutritional and microbial profile of fermented finger millet [Eleusine coracana] and foxtail millet [Setaria italica], PhD thesis, Indian Institute of Technology Madras, 1997.)

the specially designed milling equipment. Coarse and fine milling is carried out in hammer and roller mills, respectively (Rai et al., 2008). The average yield is 61% grits from whole grains with 1.2% fat content. In rural areas, milling is mostly hand-operated (Saleh et  al., 2013). Central Food Research Institute (CFTRI) in Mysore, India, commercialized a new technique that involves moist treatment of grains followed by drying to obtain 10%–12% moisture, and then dehulling to the preferred degree of pulverization. Improvement in milling characteristics is due to the high proportion of floury endosperm by the above technique. Free fatty acids below 10% are maintained in the flour during a storage period of up to 4 months (Rai et al., 2008). Milling reduces the polyphenols and phytic acid levels along with enhanced starch digestibility. In two cultivars (Kalukombu and Maharashtra Rabi Bajra) of pearl millet, the bran-rich fraction of the milling process had high in vitro protein digestibility compared to the whole and semi-refined flours (Pushparaj and Urooj, 2001). Milled grains are cooked rapidly to a soft texture, probably due to high hydration rates. In addition, grinding action during the process also causes physical damage to starch granules, thereby increasing the enzymatic action (Singh and Raghuvanshi, 2012).

6.2.2 Popping and Puffing Popping or puffing is one of the traditional food processing methods used with cereals and legumes, including millets (Saleh et al., 2013). The highly expanded end product has pleasing texture, appealing flavor, and is less dense with low bulk density. Wadikar et al. (2007) optimized puffing of different varieties of finger millet by conditioning for 2 h with 20% moisture content using hot sand at 220°C–230°C. Puffing conditions such as initial moisture content of the grains and pressure are found to be the determining factors for final quality in proso millet. Optimum puffing yield and expansion volume resulted when the grains were tempered to 15%–18% moisture

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content and gun puffed at 140 or 160 psi (Lewis et al., 1992). Studies on puffing of proso and pearl millet have shown increased protein content and in vitro digestibility. Two methods were used to prepare ladoo from popped pearl millet. In type I, roasted and dehulled chickpeas and groundnuts were added to popped pearl millet; in type II, 100% popped pearl millet was used. As expected, calcium, phosphorus, and iron contents were high in type I when compared to type II. Moreover type I ladoo had higher polyphenol and phytic acid content and lower in vitro protein and starch digestibility. In type II, cellulose and lignin content was higher (Singh and Sehgal, 2008). Popping can be done alone or in combination with other pre-treatments to produce ready-to-eat millet products that could promote utilization of millet grains on a commercial scale (Saleh et al., 2013).

6.2.3 Grits and Flour Traditionally, millets are stored as whole grains and made into flour as and when needed. The whole grains can be stored for long periods due to the seed coats, which give protection against insects. The flour has a shorter shelf life largely due to the lipids from the germ and seed coat. Roasting before grinding is an optional process that is often practiced in making flour. Grits from broken grains may be fine or coarse (rava/sooji/dalia). Pearl millet flour is prepared in the form of unleavened bread known as chapatti, and cracked and cooked millet is consumed as dalia in India and fura in Africa. Finger millet flour is prepared in southern parts of India as finger millet balls (mudde), unleavened rotis, adai, or bread. Unleavened rotis may be made either fully with finger millet or in combination with wheat flour (Malathi et al., 2012). Injera is flatbread made from teff, sorghum, corn, finger millet, or barley in Ethiopia. Kieran, a type of flatbread prepared in the Arabian Gulf, Sudan, and Iraq, is made from sorghum or pearl millet flour (Tamang and Kailasapathy, 2010; Saleh et al., 2013).

6.2.4 Germination Malting is the process of restricted sprouting of cereals under controlled conditions. Protein quality and protein efficiency ratio are improved in malting (Singh and Saini, 2012). Total soluble sugars (6.13 g/100 g), reducing (3.43 g/100 g) and non-reducing sugar (2.70 g/100 g) contents of germinated pearl millet were higher than the unprocessed grains (1.76, 0.36, 1.40  g/100  g). Germinated slurry, when processed by homogenization and autoclaving, enhanced these components further along with decreased starch content, which might be due to starch hydrolysis accompanied by emission of greater soluble sugars content (Khetarpaul and Chauhan, 1990). In a Nigerian cereal food commonly known as Fura, prepared by the germination of pearl millet grains, gave a higher nutrient and energy profile (Inyang and Zakari, 2008). Higher cell viability (8.64 log cfu/g) in pearl millet-based germinated food blend as compared to non-germinated (7.30 log cfu/g) is due to the hydrolysis of germinated flours, which facilitates better media for growth (Arora et al., 2011). There is a 29% increase in the concentration of γ-amino butyric acid (GABA) content after germination of native millets. The increase is due to the γ-decarboxylation of L-glutamic acid present in millets by enzyme glutamate decarboxylase that gets activated a result of the germination process (Peñas et  al., 2015). The extensive

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breakdown of seed-storage compounds that occurs during germination, along with synthesis of protein and other cellular components, also causes this change (Kuo et al., 2004). A significant (p ≤ 0.05) effect of germination was observed in yield, chemical composition, and the functional, rheological, and antioxidant properties of β-glucan and GABA in barnyard millet. The yield of GABA increased from 6.37 mg/100 g in raw millet to 35.70 mg/100 g in germinated millet. The functional properties of β-glucan (i.e., swelling power, water binding capacity, and 2,2-diphenyl-1-picryl-hydrazylhydrate (DPPH) scavenging activity) also increased from 1.45 to 1.76  g/g, 2.13 to 2.32 g/g and 44.39% to 57.42%, respectively (Sharma et al., 2016). The optimum conditions for producing germinated kodo millet flour with the highest total phenolics content (83.01 mg gallic acid equivalents/100 g), total flavonoids content (87.53  mg rutin equivalents/g), and antioxidant activity (91.34%) are soaking time (13.81  h), germination temperature (38.75°C), and germination time (35.82 h) (Sharma et al., 2017). These conditions resulted in increased levels of protein (6.7%–7.9%), dietary fiber (35.30–38.34 g/100 g), minerals (232.82–251.73 mg/100 g), and GABA content (9.36–47.43 mg/100 g), whereas phytates and tannins decreased from 1.344 to 0.997 mol/kg and 1.603 to 0.234 mg/100 g, respectively. The GABA content increased from 7.15 mg/100 g to 38.5 mg/100 g as a result of germination of foxtail millet. Germination along with ultrasonic assisted extraction induced a significant beneficial effect on the characteristics of polyphenolic components profile, GABA contents, and in vitro antioxidant capacity of the foxtail millet flour extracts (Sharma et al., 2018).

6.2.5 Fermentation Fermented food products from millet flour have long been a part of the traditional practices of many countries in Africa and Asia. Combination of millets with other cereals, such as wheat, maize, and rice, are common. Many studies have documented the advantages of fermentation in millets. Fermentation by endogenous microflora increased the total soluble sugars and reducing sugars with a simultaneous decrease in the starch content. The protein extractability and albumin/globulin fractions were improved. The beneficial long-chain fatty acid profile of raw flour was retained. Acetic and butyric acid were the major short-chain fatty acids produced. Most of these changes occurred in the first 24 h of fermentation of finger millet (Antony et al., 1996a). Fermentation decreased the starch and long-chain fatty acid content. The pH dropped by 2.1 units, leading to an increase of 6.5 and 3.7 times in lactic and acetic acid contents, respectively. These were the major organic acids produced during fermentation. The total fat content decreased by about 42.9%, which favorably agreed with total loss in long-chain fatty acid content. The total microbial flora increased rapidly during the first 24 h of fermentation. Controlled fermentation using a mixed-culture inoculum taken from 18 and 48  h fermented millet decreased the fermentation time markedly as measured in terms of pH and titratable acidity (Antony et al., 1996b). Major biochemical changes occurred during fermentation (6–18  h) compared to germination (24 h). The processing decreased the pH from 5.8–3.8 and increased the total sugars (2-fold), reducing sugars (13-fold), and free amino acids (10-fold). Lactic acid was the predominant organic acid (3.7%). While the phytate content decreased

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by 60%, the HCl-extractable minerals increased by 47%. The phytate-Ca/Zn molar ratio decreased from 163 to 66.2, an indication of increased zinc bioavailability. A combination of germination and fermentation is a potential process for decreasing the antinutrient levels and enhancing digestibility (Sripriya et al., 1997). The microbial population increased until 18–24 h accompanied by a rapid decrease in total and reducing sugars. The microflora stabilized between 24 and 48 h, during which time the total and α-amylase activities increased with accumulation of sugars. Total free amino acids also increased. Yeast counts were low and molds and coliforms were absent. Pediococcus species dominated (>80%) the latter half of natural fermentation of finger millet (Antony and Chandra, 1997). Fermentation of finger millet flour using endogenous grain microflora showed a significant reduction of these components (phytate 20%, phenols 20%, tannins 52%, and trypsin inhibitor activity 32%) at the end of 24  h. There was a simultaneous increase in HCl-mineral extractability (Ca, 20%; P, 26%; Fe, 27%; Zn, 26%; Cu, 78%; Mn, 10%), soluble protein, in vitro protein digestibility (23%), and starch digestibility (Antony and Chandra, 1998). S. typhimurium was completely inhibited (100%) in 12 h by the 24 and 48 h and after 48 h by the 12 and 18 h fermented samples. Escherichia coli was less inhibited than S. typhimurium, as the 48 h fermented sample showed about 50% inhibition in 12 h and 100% at 48 h. Inhibition of both pathogens was more effective after a longer period of fermentation, suggesting that metabolites produced by the fermenting microbes play a role in this effect. The unfermented millet sample (0 h) also inhibited the pathogens on prolonged incubation for 48 h (Antony et al., 1998). Two varieties of finger millet (Eleusine coracana)—a tannin-containing red variety, CO13, and non-tannin white variety, CO9—processed by treatment with enzymes (cellulase and hemicellulase) and fermented with starters (from previously fermented finger millet batter), achieved the desirable goals of reduced fermentation time (12 h), increased acidity (2.2%–2.4%), enhanced in vitro protein digestibility (IVPD, from 14% to 26%), and mineral availability compared to 48 h uncontrolled natural fermentation (Antony and Chandra, 1998). Fermentation with starters alone increased titratable acidity (1.02%–1.88%), IVPD (5.5%–22%), and mineral availability, and decreased phytate (23%–26%) and tannin (10.8%–40.5%) in the millets. Enzymatic treatment (3 h, 50°C) did not alter the pH, phytate, tannins, IVPD, or HCl-mineral extractability, but enhanced fermentative changes. The changes were marked when the 48 h starter was used and the improvements in nutrient availability was greater in the CO13 variety (Antony and Chandra, 1999). Incorporation of finger millet and pearl millet in idli batter decreased fermentation time from 12 to 6 h and 8 h, respectively (Chelliah et al., 2017), suggesting enhanced fermentation in the presence of millets. Fermentation also affects the phytochemicals and bioactive components of millets, most of which are concentrated in the seed coat and contribute to the color of the grains as seen in Figure 6.3. The total polyphenols decreased (10.376  ±  0.05 to 3.269  ±  0.08  μg g−1) during 48  h of fermentation. Lactobacillus casei KS9, Enterococcus faecalis KS4, and Saccharomyces cerevisae KS10 were found to be dominant in the 18  h fermented finger millet flour (Ramakrishnan et al., 2016a). The highest antimicrobial activity was also observed at 18 h of fermentation against 6 types of clinically isolated dysentery causing pathogenic microorganisms. Fermented finger millet extract at dilution

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FIGURE 6.3 Colored varieties of finger millet grains. (From www.milletindia.org.)

of 200 mg mL−1 had mild activity against Aspergillus fumigatus and Staphylococcus aureus. The highest activity was produced against Micrococcus luteus, which was comparably more than that of the standard drugs norfloxacin (10 mcg), tetracycline (30 mg), and vancomycin (30 mg). The extract of finger millet possessed some degree of antimicrobial activity especially at low dose (Ramakrishnan et al., 2016b). The extract from the raw flour natural fermented samples (RFNF) contained higher amounts of total phenolics than the extract of germinated flour natural fermented samples (GFNF). CO13 and CO14 (brown varieties, Figure 6.3) had higher total polyphenols when compared to CO9 and OUAT2 (white varieties). Catechin was predominant at 18 h in both RFNF and GFNF of CO13 (Ramakrishnan and Antony, 2014). Fermentation and cooking caused a more than 2-fold increase in soluble phenolic compounds, condensed tannins, and individual phenolic compounds in finger millet sour porridge of Zimbabwe (Gabaza et al., 2016). Five strains of Enterococcus hirae and one each of Enterococcus facecalis, Bacillus amyloliquefaciens, and Lactobacillus plantarum isolated from Koozh (a traditional millet fermented food of South India) showed probiotic features: resistance to acid (2.5 pH for 6 h), resistance to 0.3% ox bile, moderate hydrophobicity (40%), antibacterial activity against 10 pathogens, and susceptibility to 50% of antibiotics tested (Ilango et al., 2016).

6.2.6 Extrusion Pressure-cooking reduces the bioavailability of zinc by an extent of 63% in finger millet. In contrast, it increased to 72% in pressure-cooked sorghum. Increase in the percent iron bioavailability was higher when finger millet was subjected to microwave

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cooking. Between these two heat-processing methods, pressure-cooking is the commonly adopted practice in Indian households. The actual bioaccessible zinc content (mg/100 g) of pressure-cooked millets ranged from 0.05 (finger millet) to 0.21 (sorghum), while that of iron ranged from 0.16 (rice and finger millet) to 0.47 (sorghum) (Jing et al., 2017).

6.3 Traditional and Novel Millet Products A large proportion of cereals are processed into foods and beverages through fermentation. Although several preparations remain an art at the household level, especially in African countries, the raw grain materials and/or the type of fermentation are the main criteria to classify cereal-based fermented beverages. Traditional preparations of finger millet in India are in the form of thick porridge (kali), thin porridge (ambali), dumplings (mudde), and also beverages (chang/jnard) (Singh and Raghuvanshi, 2012). Rabadi is an ethnic fermented milk-based product, prepared by fermenting cereals, which include wheat, barley, maize, and pearl millet in the northern and western parts of India (Tamang and Kailasapathy, 2010). Kodo ko jaanr/Chhang is another fermented mild alcoholic beverage, prepared from kodo or finger millet in Darjeeling Hills and Sikkim in India, Nepal, Bhutan, and China, with a sweet taste. Rakshi is a traditional distilled kodo millet alcoholic beverage in Nepal and Tibet (Tamang and Kailasapathy, 2010; Jaybhaye et al., 2014). Burukutu and Pito are traditional African beers very commonly produced in various parts of Africa both at a traditional and industrial level (Anukam and Reid, 2009; Amadou et  al., 2011). Boza is a fermented drink also made from millets and frequently consumed in Romania and Bulgaria. Busaa is an alcoholic beverage made from maize or finger millet or from a mixture of finger millet and sorghum in Kenya. Bagni from Russia and Bantu beer from South Africa are also millet-fermented products (Tamang and Kailasapathy, 2010). Chyang/chee often made with finger millet/barley is a mildly alcoholic and slightly sweet, as well as acidic, beverage popular in Tibet, Bhutan, Nepal, and India. Darassun is another millet alcoholic drink consumed in Mongolia; Mbege is a malted alcoholic millet drink consumed in Tanzania; Merrisa, which is made from millet and cassava, is consumed in Sudan. Oh, Sura, and Themsing are alcoholic beverages from India. Tapé is sweet or sour paste made from rice, cassava, maize, and millet, that is consumed in Indonesia. Narezushi is sea fish and millet fermented paste consumed widely in Japan (Tamang and Kailasapathy, 2010). Lactic acid bacteria (LAB, Lactobacillus and Pediococcus spp.), Enterobacter spp., yeasts (Candida, Debaryomyces, Endomycopsis, Hansenula, Pichia, Saccharomyces, and Trichosporon spp.), and filamentous fungi (Amylomyces, Aspergillus, Mucor, and Rhizopus spp.) are mainly used for the manufacture of cereal-based alcoholic beverages (e.g., tchoukoutou, jnard), nonalcoholic beverages (e.g., uji, ben-saalga), porridges (e.g., mawè), and cooked gels (e.g., kenkey, idli, and mifen) (Nout, 2009). Since consumption of wheat and rice has replaced millet utilization, most of the above traditional fermented foods (Table 6.1) are slowly disappearing. Additionally, no documented evidence is available on the particular type of millet used in those preparations. In other cases, the foods are prepared from the locally grown millets. Braga is called Boza in Turkey and Busa in southeastern Europe (Table 6.1).

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TABLE 6.1 Most Common Indigenous Millet-Based Fermented Foods and Beverages Substrates Finger millet malt Pearl millet Millet

Product Doro

Yeasts and bacteria

Dalaki Bagni Braga Darassum Jaanr

Unknown Unknown Unknown Unknown Hansenula anomala, Mucor rouxianus

Kunun-Zaki

Lactic acid bacteria, yeasts Unknown

Mangisi

Finger millet and maize Pearl millet and sorghum Pearl millet or sorghum, maize

Microorganisms

Thumba Chikokivana Merissa Ogi

Pearl millet, maize, sorghum

Uji

Pearl millet or maize, kaffir corn, and munkoyo roots Millet or rice

Munkoyo

Millet, maize, wheat and other cereals

Boza

Busa

Nature of Use

Regions

Colloidal thick alcoholic drink Thick porridge Liquid drink Liquid drink Liquid drink Alcoholic paste mixed with water Paste used as breakfast dish Sweet-sour non-alcoholic drink Liquid drink Alcoholic beverage Alcoholic drink

Zimbabwe

Lactobacillus plantarum, Saccharomyces cerevisiae, Candida mycoderma, Corynebacterium, Aerobacter, Rhodotorula, Cephalosporium, Fusarium, Aspergillus, Penicillium Leuconostoc mesenteriodes, Lactobacillus plantarum Unknown

Paste as staple. For breakfast or weaning food for babies

Nigeria, West Africa

Porridge as a staple

Kenya, Uganda, Tanzania

Liquid drink

Africa

Lactobacillus, Saccharomyces Lactobacillus, Saccharomyces cerevisiae, Leuconostoc

Liquid drink

Syria, Egypt, Turkistan Albania, Turkey, Bulgaria, Romania

Endomycopsin fibuliger Saccharomyces cerevisiae Saccharomyces

Thick, sweet, slightly sour beverage

Nigeria Caucasus Romania Mongolia India, Himalaya

Nigeria Zimbabwe

East India Zimbabwe Sudan

Source: Adams, M.R., Fermented weaning foods, in: Microbiology of Fermented Foods, Springer, Boston, MA, pp. 790–811, 1998; Sankaran, R., Fermented foods of the Indian subcontinent, in: Microbiology of Fermented Foods, Springer, pp. 753–789, 1998; Soni, S.K. and Sandhu, D.K., Ind. J. Microbiol., 30, 135–157, 1990.

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6.3.1 Ethnic Fermented Foods of Asia 6.3.1.1 Jnard Jnard (or Channg) is a traditional fermented liquor similar to beer prepared from millet and barley in India and Nepal. Mucor indicus, also as known as Mucor rouxii, Amylomyces rouxii, Chlamydomucor rouxii, and Mucor rouxianus, is a Zygomycetes fungus originally separated from Jnard. This dimorphic fungus is capable of producing valuable products such as bioethanol, glucosamine, and polyunsaturated fatty acids, especially gamma-linolenic acid, an omega-6 fatty acid (Sharifyazd and Karimi, 2017). The cereal-based alcoholic beverage is stored in dry fruit shells (used as pots) of Lageneria siceraria (Molina) Standley (Cucurbitaceae family), locally called Chindo and considered sacred by the Rai community (Darjeeling Hills, Assam) during worship of deities (Chettri et al., 2014). Traditionally, Jnard is blackslopped using a starter called a Murcha. The grains are boiled, drained, cooled, mixed with 1%–2% (w/w) powdered Murcha, packed in a bamboo basket, and left for 2–4 days (saccharification process). A sweet aroma that is emitted acts as an indicator and the slurry is transferred to an earthen pot and covered to make it airtight for fermentation. Subsequently, the seeds are squeezed by hand to remove seed coats and placed in a bamboo/wooden vessel with warm water added to it. The beverage is ready for consumption after 10 min (Tamang and Sarkar, 1995). The mixed population of molds, yeasts and lactic acid bacteria in Murcha remains active during this process and modifies the substrate as well as increases the temperature of the slurry by 4°C above the ambient temperature (20°C–25°C) within two days of fermentation. Amylase activity is the highest on the second day of fermentation due to the active role of mucoraceous fungi in saccharification and liquefaction of starch. The initial dominant molds Mucor circinelloides, Rhizopus chinensis, and the yeast Saccharomycopsis fibuligera disappear within 12 h of fermentation. Consequently, mature Jnard contains yeasts (105 –107  CFU g−1) such as P. anomala, S. cerevisiae, and C. glabrata, as well as lactic acid bacteria (105 –10 6 CFU g−1), which includes Pediococcus pentosaceus and Lactobacillus bifermentans (Tamang et al., 1988).

6.3.1.2 Koozh Koozh is another fermented beverage made with pearl or finger millet flour and rice, and is widely consumed in Tamil Nadu (Ilango and Antony, 2014). Fermentation helps in reduction of antinutrients and enhances protein, starch, and mineral availability (Antony and Chandra, 1998). Koozh is one of the most popular fermented millet preparations due to its aroma, flavor, and high nutritive values, which has a strong connection with South Indian culture. It is claimed to be healthy due to the presence of live beneficial microorganisms, thereby featuring huge functional values to this traditional product (Thirumangaimannan and Gurumurthy, 2013). The preparation of Koozh includes two fermentation processes—primary fermentation (before) and secondary fermentation (after cooking). The finger millet flour is mixed with water in the ratio of 2:1. Primary fermentation is carried out at ambient temperature for 12–15 h. The slurry is then cooked with added

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Millet slurry prepared with tap water (1:1 w/v) is fermented for 16 h

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Broken rice is added to fermented slurry and cooked as porridge

The porridge is fermented for 16 h and made into balls (Kali)

Koozh is consumed within 12 h along with accompaniments

Kali stored at room temperature is mixed with tap water (1:6 w/v) and salt before consumption (Koozh)

FIGURE 6.4 Schematic representation of Koozh preparation. (From Ilango, S., and Antony, U., Afr. J. Microbiol. Res., 8, 308–312, 2014.)

broken rice in earthen pots and secondary fermentation proceeds for further 12–15 h. The product created is called as Koozh as seen in Figure 6.4 (Ilango and Antony, 2014).

6.3.2 Ethnic Fermented Foods of Africa 6.3.2.1 Borde Borde is a beer consumed by Ethiopian people in the Southwestern regions. It is prepared from natural fermented maize, sorghum, and barley, or a mixture of the three. The thick, gassy, sweet-sour, whitish-gray to brown beer serves as a substitute for meals during long trips. The users believe that it enhances lactation and mothers are encouraged to drink substantial amounts of it after giving birth (Kebede et al., 2002). Fermentation of Borde has four phases marked by the introduction of ingredients into the fermentation pot at different times. In phase I (primary fermentation), maize grits are mixed with water and left to ferment at ambient temperature for 48–72 h. A portion of the fermented grits from phase I (48 h) is roasted into enkuro, a well-roasted granular mass. Fresh malt flour and water are carefully mixed by hand in a smoked insira into a pale brown thick mash. This mixture is called tinsis and it is left to ferment for 24 h. A second portion of the fermented grits from phase I (68  h) is slightly roasted into enkuro, carefully kneaded with mixed flour (wheat, finger millet, and teff) and water, and then molded into stiff dough balls. The dough balls are steamed into gafuma and then broken into pieces. Pieces of cooled gafuma are blended with the fermented tinsis and additional water in the same insira into a thick brown mash called difdif. The difdif is then allowed to ferment for 18 h. The last portion of fermented grits from phase I (72 h) is added to a pan containing a boiling mixture of whole grains of sorghum and water, and then further boiled into a very thick porridge with continuous stirring and then cooled. The gelled porridge is added to the fermented difdif, along with a small amount of additional malt. After a thorough mixing, the thick brown mash is sieved through a wonnfit (about 1 mm pore size). The residues are then wet milled

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using traditional grinding stones and sieved 2 times. The filtrates are pooled and poured back into the same rinsed insira and the fermentation is then continued for 6 h (after the addition of porridge). Actively fermenting effervescent borde is then ready for consumption.

6.3.3 Ethnic Alcoholic Beverages of Asia 6.3.3.1 Kodo Ko Jaanr The most popular fermented finger millet-based mild alcoholic beverage with sweet-sour and acidic taste is kodo ko jaanr or chyang or chee prepared and consumed by the Gorkha, the Bhutia, the Lepcha, the Monpa and many ethnic groups of the northeastern part of India. It is the most common fermented alcoholic beverage in the Eastern Himalayan regions of the Darjeeling Hills and Sikkim in India, Nepal, and Bhutan. Jaanr is the common name for all alcoholic beverages in the Nepali dialect. The Tibetan and Lepcha tribes call it minchaa chhyaang and mong chee, respectively. Seeds of finger millet, locally called kodo, are cleaned, washed, and cooked for about 30 min, and then the drained off and cooked millets are spread on a bamboo mat called a mandro for cooling. About 2% of dry powdered marcha, a mixed starter culture (Tamang et  al., 1996), is sprinkled over the cooked seeds, mixed thoroughly, and packed in a bamboo basket lined with fresh fern, locally called thadre uneu (Thelypteris erubescens), or banana leaves, covered with sack cloths and kept for 2–4 days at room temperature for saccharification. During saccharification, a sweet aroma is emitted and after 2–4 days, the saccharified mass is transferred into an earthen pot or into a specially made bamboo basket called septu, made airtight, and fermented for 3–4  days during summer and 5–7 days in winter at room temperature. Good quality jaanr has a sweet taste with a mild alcoholic flavor. Kodo ko jaanr is consumed in a unique way in the Eastern Himalayan regions of Nepal, India, Bhutan, and China (Tibet) by filling 200–500 g of fermented millet grains into a vessel called a toongbaa, and lukewarm water is added up to its edge. After 10–15 min, the milky white extract of jaanr is sipped through a narrow bamboo straw called a pipsing, which has a hole in the side near the bottom to avoid passing of grits. Water can be added twice or thrice after sipping the extract.

6.3.3.2 Madua Madua is one of the most popular and common millet-based fermented beverages prepared by almost all the tribes of Arunachal Pradesh in all districts. It is a traditional alcoholic drink prepared from finger millet. The steps of preparation of Madua are represented as a flow chart in Figure 6.5. During saccharification, sweet aroma is emitted, which is an indication of sufficient fermentation. Then the fermented mass of finger millet is transferred into a perforated bamboo basket and warm water is added drop by drop at a rate of 1 L/h onto it. The filtrate is collected in a container kept below. A good quality Madua is golden yellow in color, sweet in taste, and has a good alcoholic flavor (Shrivastava and Shrivastava, 2012).

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Millet is roasted for 30 min, cooled and cooked till soft

Addition of starter culture

The mixture is placed in perforated basket and closed with Ektam leaves

Madua is collected by pouring hot water from top

Fermented for 4 or 7 days during summer or winter, respectively

FIGURE 6.5 Schematic representation of Madua preparation. (From Shrivastava, K., and Shrivastava, B., Ind. J. Tradit. Know., 11, 81–89, 2012.)

6.3.3.3 Themsing Themsing is an alcoholic beverage prepared by the Monpa tribe of the Tawang district of Arunachal Pradesh. It is prepared from kongpu (finger millet) or bong (barley) or a mixture of both. Kongpu gives a low yield but high quality of Themsing, whereas when bong is used alone or in combination with kongpu, it gives a high yield of Themsing. Themsing looks like black tea and has a good aroma (Shrivastava and Shrivastava, 2012). The preparation of Themsing given in Figure 6.6 involves the cooking of grains of finger millet or barley. The cooked grains are spread on the bamboo mat or polythene sheet on the floor. A small amount of pham (yeast tablet made of indigenous rice paste and leaves of Solanum khasianum) is mixed thoroughly with them. Zarsi is smeared inside the zom (special wooden container for preparation of themsing) before keeping the cooked grains in it to avoid the development of a foul smell. Then the whole mixture is kept in the zom. The paste is covered with leaves of zola (Brassiopsis sp.) or banana (zola is more preferred), over which a thin layer of wooden ash is spread. Then the whole container is made airtight. A small PVC

Grains are cooked till soft and cooled on bamboo mats

Addition of starter culture along with a pinch of ash or charcoal

Fermentation in wooden containers closed with zola or banana leaves

Themsing is consumed by adding luke warm water to the fermented mixture

Fermented mix can be stored for 1-3 years

FIGURE 6.6 Schematic representation of Themsing preparation. (From Shrivastava, K., and Shrivastava, B., Ind. J. Tradit. Know., 11, 81–89, 2012.)

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pipe that has a diameter of approximately 1 cm is fitted at the bottom of the container and packed with yak ghee. The drink is dripped out from the pipe and collected in a container. The container is kept undisturbed for 1–3 years (Shrivastava and Shrivastava, 2012). In another method of extraction of Themsing, fermented mass is transferred into a perforated bamboo basket, lukewarm water is added slowly, and the filtrate of the liquor is collected in a container. The filtrate has a golden color and good aroma. It is used in curing certain ailments such as muscle pain, and added as an ingredient in the formulation of certain local medicines. These medicines are formulated with local beverages (rakshi and lohpani) and given after the delivery of a child, during stomach pain, dysentery, and chhatpa (a syndrome affecting people from cooler regions when they go to hotter places (Shrivastava and Shrivastava, 2012).

6.3.3.4 Rakshi Rakshi is an alcoholic beverage prepared by the Monpa, Miji, and Mishmi tribes residing in the West Kameng and Tawang districts of Arunachal Pradesh. This drink is prepared from barley, rice, finger millet, and/or maize (Figure 6.7). The methodology of Rakshi preparation is elaborated in the following flow chart. These grains are cooked until soft and spread on a bamboo mat (charang). Yeast tablets (pham) are added to the lukewarm seeds, covered with a plastic sheet, and kept for 2–3 days to begin fermentation. After fermentation, water is added to the fermented stock and a large vessel containing fermented material is kept on a fire. A small metallic container is kept inside the large vessel above a triplet stand to collect the distillate. The grains are cooked in an aluminum container that has a special arrangement from which the Rakshi is extracted by distillation. A wide vessel containing cold water is kept above the large vessel as a condenser whose water is changed at frequent intervals to keep the water continuously cool. The drink prepared in this method has a good alcoholic aroma and a very effective ethanol taste. It looks like distilled water (Shrivastava and Shrivastava, 2012).

6.3.4 Novel Millet Products Traditional food habits are changing due to a number of factors including sociodemographic transition, urbanization, changing lifestyles, globalization, diverse food patterns, and movement away from traditional foods. The new innovation in food products is also due to a surge in convenience foods in the market. Corn and oats as

Grains are cooked till soft and cooled on bamboo mats

Addition of starter culture

Fermented for 7 or 14 days during summer or winter, respectively

Rakshi is consumed after distillation of fermented mixture

FIGURE 6.7 Schematic representation of Rakshi preparation. (From Shrivastava, K., and Shrivastava, B., Ind. J. Tradit. Know., 11, 81–89, 2012.)

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breakfast cereals have been occupying the commercial market for the last 25–30 years. This is to a certain extent being replaced by flaked and/or puffed millets. Millet flour is widely available on the market, and can be used to make many food preparations. Also, instant millet mixes, which are combinations of pulse flour, spices, and salt, are gaining acceptance. This makes food preparation easier and convenient for the consumer. The nutritive value of millet-based foods can be enhanced further by supplementation with legume protein. These include cereal bars, which are made with puffed or flaked wheat and oats, along with nuts and fruits. Puffed and flaked millets could be a promising replacement. Composite flours, made of blends of wheat and other cereal/millet flours, became prevalent when wheat was scarce (Dendy, 1992). Composite flour is widely used these days in products such as porridge, baked products, extruded products, beverages, etc. Composite flours made from finger millet can be used in the preparation of various recipes and can be effectively used for supplementary feeding programs (Singh and Raghuvanshi, 2012). Bakery products are more popular and commonly consumed worldwide. Commercially baked products such as breads, cakes, and biscuits are usually made with 100% wheat flour. Millet based products in which the wheat flour is either partially or fully replaced with millet flours, such as finger millet, pearl millet, and barnyard millet, are gaining importance. Restriction of usage of millet flours in bread and cakes is due to lack of gluten, which otherwise gives the viscoelastic properties. Current studies on baked millet products done for its viability and acceptability revealed that they were comparable to that of wheat-based products (Rathi et al., 2004; Singh et al., 2006; Saha et al., 2011; Angioloni and Collar, 2012; Schoenlechner et al., 2013; Chakraborty et al., 2016). New baked products like millets enriched cakes are made by replacing 50% of the refined wheat flour with finger millet flour. Similarly, bread containing foxtail millet flour is also made with a 50% replacement of wheat flour. Also, pizza crusts, which are traditionally made with 100% wheat flour, could be replaced with 50% barnyard millet (Dayakar Rao et al., 2017). Biscuits made from blanched and malted pearl millet flour were found to be organoleptically acceptable, with a good mineral profile and a low amount of antinutrients. Biscuits prepared from blanched flour had high calcium, phosphorus, iron, and manganese content when compared to biscuits prepared from malted flour. Low antinutrient content and high in vitro digestibility were observed in biscuits prepared from blanched flour. The addition of soy flour increased its mineral and protein profile (Singh et al., 2006). Leavened bread made from different compositions of soy-barnyard millet flour blends resulted in varying texture, color, and specific volume due to changes in moisture handling abilities of the soy-barnyard millet food matrix (Chakraborty et al., 2016). Traditional rice noodles that are made from white rice are more popular in parts of South India and Sri Lanka were developed with finger millet and rice flour at a 50:50 and 100:0 ratio. Sensory analysis revealed that although both types of noodles made with finger millet were highly acceptable, the noodles made with 100% finger millet showed higher acceptability in color than 50% finger millet noodles (Dissanayake and Jayawardena, 2016). Different blends of finger millet flour, oat flour, potato starch, and whey protein isolate were subjected to a twin screw extrusion process and dried, which, when further deep fried or microwaved or roasted, resulted in good quality protein-rich extruded snack products (Salunke, 2015).

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6.4 Nutritional and Health Benefits Millets are recognized nutritionally for being a good source of nutrients, particularly micronutrients, as seen in Table 6.2. In addition to their cultivation advantages, millets are found to have high nutritive value comparable to that of major cereals such as wheat and rice. They contain about 5%–8% protein, 65%–75% carbohydrates, and 15%–20% dietary fiber (Chethan and Malleshi, 2007), in addition to low fat (1.3%) content. The crude fiber (3.6%) of finger millet is markedly higher than wheat (1.2%) and rice (0.6%). The carbohydrate content of millets is similar to that of other major cereals. They also contain significant amounts of dietary fiber, both insoluble and soluble, that can be helpful in reducing chronic vascular complications (Lebovitz, 2001). The nonstarch polysaccharides of millet form bulk of the dietary fiber constituents and offer several health benefits including delayed nutrients absorption, increased fecal bulk, and lowering of blood lipids. Studies have shown that the higher dietary glycemic index (GI), which is a measure of both quality and quantity of carbohydrates due to intake of refined grains such as white rice, are associated with the risk of type 2 diabetes among urban South Indians (Mohan et al., 2009). The development and availability of low GI foods are limited, especially to millets as opposed to refined major cereals. The quality of protein is due to the function of its essential amino acids. Millet contains 44.7% essential amino acids (Mbithi-Mwikya et al., 2000), which is higher than the 33.9% essential amino acids in Food and Agriculture Organization reference protein (FAO, 1991). Finger millet is rich in isoleucine, methionine, tryptophan, threonine, and valine, which are vital in the normal functioning of the human body and are also essential for repairing body tissues. Another essential amino acid not

TABLE 6.2 Nutrient Composition of Millets per 100 g Edible Portion Millets Component Protein (g) Fat (g) Crude fiber (g) Carbohydrates (g) Dietary fiber (g) Calcium (mg) Iron (mg) Zinc (mg) Thiamine (mg) Riboflavin (mg)

Barnyard

Finger

Foxtail

Kodo

6.2 2.2 9.8 65.5

7.3 1.3 3.6 72.0 19.5 344.0 3.9 2.3 0.4 0.2

12.3 4.3 8.0 60.9 19.4 31.0 2.8 2.4 0.6 0.1

8.3 1.4 9.0 65.9 37.8 27.0 0.5 0.7 0.3 0.1

27.0 0.5 3.0 0.33 0.1

Pearl 11.6 5.4 1.2 67.5 11.5 42 8.0 3.1 0.33 0.25

Proso 12.5 1.1 2.2 70.4 8.5 14.0 0.8 1.4 0.2 0.2

Source: Gopalan, C. et  al., Nutritive Value of Indian Foods, National Institute of Nutrition, Indian Council of Medical Research, Hyderabad, India, 2004; Kumari, D. et al., Food Sci. Nutr., 5, 474–485, 2017; Sharma, S. et al., Food Chem., 233, 20–28, 2017.

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found in most cereals is methionine, which is useful in eliminating fat and the main provider of sulphur for the body. Sulphur is essential for production of glutathione (the body’s natural antioxidant). Prolamin is the major fraction of finger millet protein, being 24.6%–36.2% of total protein (Lupien, 1990). Antony and Chandra (1998) reported 99.1 mg soluble protein per 100 g in finger millet. Tryptophan is usually the second most deficient amino acid in cereals; however, it is present in finger millet. It also contains threonine, in contrast to rice, wheat, and sorghum. Since these are gluten free, they can be used by celiac patients for their healthy lifestyles. γ-Amino butyric acid (GABA) is a free modified amino acid that could help in the inhibition of cancer cell proliferation and reduction of blood pressure. γ-Amino butyric acid acts as a strong secretagogue of insulin from the pancreas, effectively prevents diabetes, acts as an inhibitory neurotransmitter in the brain and spinal cord of mammals, and is involved in regulation of blood pressure, heart rate, and alleviation of pain (Bai et al., 2008). The γ-amino butyric acid content increased during fermentation of kodo millet and foxtail millet. Millets are recognized nutritionally for being a good source of the minerals magnesium, potassium, calcium, sodium, manganese, and phosphorus (Shashi et  al., 2007). According to Vijayakumari et al. (2003), finger millet is a very rich source of calcium and iron. The deficiency of calcium, which leads to bone and teeth disorders, as well as iron deficiency leading to anemia, can be overcome by introducing finger millet in our daily diet. It has the highest calcium content among all cereals (344 mg per 100 g). Singh and Srivastava (2006) reported the iron content (3.61–5.42 mg per 100 g) for 16 finger millet varieties with a mean value of 4.4 mg per 100 g. They also observed that the zinc content varied from 0.92 to 2.55 mg per 100 g with a mean value of 1.34 mg per 100 g. The phosphorus content was reported to be 130 to 295 mg per 100 g with a mean value of 180.43 mg per 100 g by the same authors. If it is consumed regularly, malnutrition deficiency, degenerative diseases, and premature aging can be overcome. The total carotenoids content of finger, little, foxtail, and proso millets varied from 78 to 366 mg per 100 g. The tocopherol content of finger millet (3.6 mg per 100 g) was higher than in foxtail and little millet varieties (~1.3 mg per 100 g). High performance liquid chromatography (HPLC) analysis of vitamin E indicated a higher proportion of γ- and α-tocopherols and lower levels of tocotrienols (Asharani et al., 2010). Finger millet contains both lipid-soluble and water-soluble vitamins like thiamin, riboflavin, and niacin, as well as ascorbic acid and tocopherols (Obilana and Manyasa, 2002). Water-soluble B-vitamins of finger millet are concentrated in the aleuronic layer and germ, whereas the lipid-soluble vitamins are mainly located in the germ.

6.4.1 Other Functional/Bioactive Components Electro Spray Ionization Mass Spectra (ESI-MS) revealed xylobiose as the major sugar in the water-soluble xylan (WSX) of the finger millet seed coat. The xylooligosaccharides (XOS) exhibited an antioxidant activity of 75% and prebiotic efficacy. The cell-free supernatant of Lactobacillus plantarum grown on the XOS from finger millet seed coat showed strong antibacterial activities against pathogenic microorganisms compared with commercial XOS. Finger millet seed coat represents an abundant and alternative source for the extraction of xylan and its use for prebiotic XOS production (Palaniappan et al., 2017).

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Millet seed coats are excellent sources of bioactive compounds such as polyphenols, bioflavaonoids, and phytates. The millet polyphenols are a complex mixture of benzoic acid and cinnamic acid derivatives and exhibit enzyme inhibitory and anticataractogenic activities (Devi et al., 2014). The phenolic antioxidants have been found to play an effective role in lowering cholesterol, blood pressure, and obesity, and increasing overall immunity of the system. They have also been reported to act as anticancerous and antiviral agents. The derivatives of polyphenols provide natural protection against infections by pathogenic microorganisms (Banerjee et al., 2012). In a study by Kumari et al. (2017), soluble and bound phenolic compounds were extracted from different varieties of millet types, namely finger millet, foxtail millet, and proso millet, cultivated at dry and intermediate climatic zones in Sri Lanka. The highest phenolic content and antioxidant activities were reported for millet samples cultivated in areas belonging to the dry zone in Sri Lanka. Addition of finger millet and pearl millet flour (10% w/w) to idli batter enhanced the dietary fiber by 28% and 23%, calcium by 113% and 56%, and iron by 51% and 258% in the respective idlis (Chelliah et al., 2017). Since appreciable amounts of polyphenols are found in finger millet, especially in the brown varieties, they can be considered as a rich source of antioxidants among cereals (Ramakrishnan and Antony, 2014). The effect of processing methods like germination and fermentation on the varieties of finger millet with different seed coat color has a high impact on the polyphenols content. The essential content of polyphenols and specifically catechin can promote the use of finger millet as a functional food among other cereals like rice and wheat. The changes in polyphenols during traditional processing methods in the preparation of indigenous foods will meet the needs of the development of novel dietary products. The exploration of phytochemicals with antioxidant properties is essential for human health and nutrition research (Ramakrishnan and Antony, 2014). A study by Ragupathy et  al. (2016) recorded the traditional knowledge of local farmers who emphasized the nutritional importance of all landraces of small millets. The traditional way of consuming millet products and the value of millet porridge called Kapai (ragi or finger millet) as food had long been appreciated in their culture. This is known to be high in protein, and a good source of starch, vitamins, and minerals such as iron and phosphorus (Barbeau and Hilu, 1993; Vadivoo et al., 1998). Fermented finger millet is a good source of probiotics (Antony et al., 1998). The millet was regularly consumed by all ages and genders. The porridge is a breakfast staple for many households since the farmers feel very satisfied and strong after consuming it rather than with other types of food. The starch found in millet is digested slowly, supplying a slow constant supply of energy (Dharmaraj and Malleshi, 2011). Similarly, other farmers believe that consumption of finger millet-based food helps control obesity. In fact, many farmers claim to use millet to control diabetes due to its low glycemic load (Dharmaraj and Malleshi, 2011; FAO, 1995). Pregnant and lactating women in many households preferred a millet-based diet because it provided energy as well as prevented weight gain and helped induce lactation and maintain optimal body temperature and energy levels after delivery. Furthermore, consumption of fermented finger millet helps individuals recover from stomach disorders caused by overconsumption of liquor. This is very common as the traditional product is a street-vended food in towns and cities of Tamil Nadu (Patel et al., 2014). Ilango et al. (2016) have reported the functional characteristics of probiotic bacteria isolated from market samples of Koozh.

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According to Chandra et al. (2016), who have reviewed the health benefits of finger millet, the nutritional profile and abundance of these phytochemicals enhances “the nutraceutical potential of finger millet, making it a power house of health benefiting nutrients.” It has distinguished health benefits include antidiabetic (type 2 diabetes mellitus), antidiarrheal, anti-ulcer, anti-inflammatory, antitumerogenic (K562 chronic myeloid leukemia), and anti-atherosclerogenic effects, as well as antimicrobial and antioxidant properties. The health promoting value of other minor millets is yet to be studied in depth, which can open up avenues for their utilization, so that millets may be recommended for use in the formulation of nutraceutical products.

6.5 Conclusion The miniscule millets with mega and multi potential are yet to be effectively used. Their nutritive value in terms of dietary fiber, as well vitamins and minerals, particularly the micro-minerals, are indeed superior to the major refined cereals. Their bioactives have several health benefits that may be suitably utilized for preventive and therapeutic purposes. Being gluten free and having several ecological advantages, they are indeed our best hope for sustainable systems for the future, particularly in Asian and African countries. The traditional methods of processing have to be leveraged to suitable scales with modern technology. Their incorporation in familiar and novel foods can achieve diet compliance and several health benefits to the consumer.

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7 Oats Gabriela Y. Campos Espinosa, Mallory E. Walters, and Apollinaire Tsopmo CONTENTS 7.1 7.2

Introduction .................................................................................................... 129 Processing ...................................................................................................... 130 7.2.1 Storage ............................................................................................... 130 7.2.2 Cleaning............................................................................................. 132 7.2.3 Dehulling ........................................................................................... 132 7.2.4 Kilning............................................................................................... 132 7.2.5 Cutting and Flaking........................................................................... 133 7.2.6 Milling ............................................................................................... 133 7.3 Product Development ..................................................................................... 134 7.3.1 Oatmeal and Breakfast Cereals ......................................................... 135 7.3.2 Fermented Products and Drinks........................................................ 135 7.3.3 Bakery and Pasta Products ................................................................ 136 7.3.4 Fat Replacers ..................................................................................... 137 7.4 Nutritional Aspects and Health Benefits........................................................ 137 7.4.1 Nutritional Value and Biological Effect of Oat Proteins ................... 139 7.4.2 Nutritional and Biological Effects of Oat Polysaccharides ............... 140 7.4.3 Biological Effects of Oat Phytochemicals ......................................... 141 7.5 Conclusion ...................................................................................................... 142 References ................................................................................................................ 142

7.1 Introduction Cereals are staple foods and have been grown for human consumption and feeds since the beginning of civilization (Gani et al. 2012). Worldwide, they can contribute to about half of the human energy requirement. Among the majorly consumed grains, oats rank fifth after wheat, rice, corn (or maize), and barley. Grains provide carbohydrates, proteins, B-vitamins, and minerals for a major portion of the world’s population (Rosell 2011). Oats are often consumed as whole and this is the reason they provide the human body with the most nutrients and active secondary metabolites compared to other grains because the majority of bioactive compounds are located within whole grains, bran, or germ rich milling fractions. During the nineteenth century, oats gradually

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became an important part of the human diet (Webster 2011). Meanwhile, livestock feed is still their primary use, accounting for about 74% of the world’s total oat usage between 1995 and 2005 (Strychar 2011). Today, oats are present in a variety of foods like oatmeal, breakfast cereals, beverages, bread, and infant foods (Yao et al. 2006; Zhang et al. 2007). Oats rank sixth in the world in grain production following maize, wheat, barley, sorghum, and millet and are mainly grown in Europe and North America. These areas have the appropriate climate (i.e., cool and moist) to which oats are best adapted. Temperature and moisture conditions are the common limiting factors as to where oats are grown (Forsberg and Reeves 1995). Canada, the United States, the European Union (EU), Russia, and Australia production account for nearly 77% of the world’s supply of whole grains, seeds, and industrial-grade oats. Leading producers in the EU are Finland, Germany, Sweden, and Poland. The average global production of oats from 2003 to 2008 was 24.91 million tonnes (Strychar 2011). The largest global commercial producer and exporter of oats is Canada, producing 3,736 thousand tonnes of oats (an average calculated from data from 2003 to 2008), which accounts for 15% of total global production and about 60% of global exports (Strychar 2011). There are two cultivated species; the first, Avena sativa L., also referred to as covered or hulled oats, is the most cultivated oat species in the world (White 1995). The second, A. sativa var. nuda, referred to as naked or hull-less oats has a hull loosely attached to the groat. The grain quality of the naked variety is good but it is more prone to mechanical damage and generally has lower yields compared to covered varieties (Lásztity 1998). The increased human consumption of oats has led to many research investigations. They are aimed at developing new food products, identifying phytochemicals or active compounds, and determining the physiological effect of oat-based products or their constituents. The aim of this chapter is to describe oat processing methodologies and its usage in product development, and to summarize the physiological function of food products and purified compounds.

7.2 Processing Oats are harvested when crops are mostly ripened, and the kernel moisture has reached an accurate level. Frost damage is a concern with later harvest in the fall. The harvesting is accomplished by either swathing or direct combining. The first involves cutting oats and placing them in rows directly on the cut stubble; kernels are allowed to dry in the field from a starting moisture of about 35% to 12%–14% and then subsequently threshed. In direct combining harvesting, the crop is left to dry longer while still standing in the field, and then cut and threshed in one step at a similar moisture. Harvested oats may be placed into on-farm storage or sold immediately to milling companies or local elevators. In the latter, standardized sampling and grading procedures are employed upon receipt to establish fair market value and milling quality (Menon et al. 2016).

7.2.1 Storage Proper storage and handling of oats is important to decrease nutrient loss and to minimize the formation of off-flavors resulting from lipid oxidation because like

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other grains, oats are sensitive to their storage environment (Arendt and Zannini 2013). Inadequate conditions can result in the growth of microorganisms that can cause spoilage, some of which can produce toxic compounds such as aflatoxins (Decker et al. 2014), develop of hot spots, and increase activity of hydrolytic enzymes with subsequent rapid increase in free fatty acid contents (Arendt and Zannini 2013). The recommended storage conditions for oats are stored 0.65 water activity (approximately 13% moisture in the kernels) between a temperature of 5°C to 20°C (Decker et al. 2014). It has also been reported that a period no longer than 12 months is necessary in order to avoid loss of antioxidant compounds such as phenolics (Rakić et al. 2014). The processing is designed to remove foreign materials, isolate and stabilize the groat and convert it into a form that is easy to cook (Rasane et al. 2013). This involves cleaning, grading, dehulling, and kilning, and then cutting, flaking, or producing flour (Figure 7.1). Oat milling is performed to get good quality, appearance, and taste. Oats

Pre-cleaning

Storage

Cleaning and grading

Dehulling

Kilning

Kilned groats

Cutting

Rolled oats

Flaking

Milling

Oat flakes

Oat flour

Quick oats

Instant oats

FIGURE 7.1 Oat processing diagram. (Adapted from Menon, R. et al., Oats—From farm to fork, in Advances in Food and Nutrition Research, edited by Henry Jeyakumar, Vol. 77, pp. 1–55, Elsevier, 2016; Girardet, N. and Webster, F., Oat milling: Specifications, storage, and processing, in Oats: Chemistry and Technology, 301–309.)

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7.2.2 Cleaning As with other agricultural products, harvesting oats will lead to their comingling with other components found in the field and the removal of these foreign materials is necessary to make oats suitable for human consumption. The cleaning consists of screening, aspiration, and size separation to remove oversized and unwanted material (Menon et al. 2016). Oats enter the mill, pass under a magnetic separator to eliminate metallic objects, and then move through a series of rotating or oscillating screens to retain large objects (straw, sticks, and stones), while letting through small objects, such as underdeveloped oats, dirt, weed seeds, and dust. These screens are typically perforated metal with elongated slots, but may also be made of weaves of coarse wire mesh (Menon et al. 2016). The retained oat stream is then subjected to aspiration that removes lighter particles. A dry stoner then removes high-density but similar sized particles such as rocks and other grains. In some cases, oats undergo clipping before cleaning, cutting off the tip of the oats to make later dehulling more efficient. Clipping utilizes a meshed screen into which the narrow end of the oat can penetrate. A rotating bar then displaces the oat from the mesh resulting in the tip being broken off, and the cut-off tips are removed by aspiration. Another step is performed in order to sort the oats into different size classes, which can increase milling efficiency by eliminating small kernels that do not have a large percentage of groat. An indented rotary drum (separator) is used for this process. Some small oats such as light oats, double oats, and pin oats can be removed by this process and are used as animal feed. The isolated clean oats are divided into different sizes using differences in densities and weights (Rasane et al. 2013; Decker et al. 2014).

7.2.3 Dehulling The hull is highly indigestible and is therefore removed to enhance nutritional benefits through a process known as dehulling. Cleaned raw oat grains are forced centrifuged against an impact ring or rubber liner that causes the separation of the hull from the groat (Ames et al. 2014). Air aspiration then separates the dehulled groats from the hulls (Serna-Saldivar 2010). This procedure is to polish the groats through removal of remaining pieces of hull material and the trichomes. The efficiency of dehulling is dependent on weight and moisture contents (normal range 12%–13%) as higher levels decrease dehulling while lower contents increase groat-breakage rates (Girardet and Webster 2011). Factors such as glucan and protein concentrations may also affect the dehulling process (Arendt and Zannini 2013). The dehulling efficiency is generally about 85% to prevent excessive breakage. Groats broken during dehulling are sorted on sizing systems. For end products requiring high levels of dehulled oat removal (such as cut oats), groats are cut and sorted into small and large pieces using sifters. Finally, perforated drums are used to remove contaminating grains such as wheat and barley that are larger than the groats (Decker et al. 2014).

7.2.4 Kilning Oats contain higher fat (6%–8%), including polyunsaturated fatty acids and enzymes (lipases, lipoxygenases), compared to 2%–3% for most other grains. Phospholipids and other triglycerides are then susceptible to hydrolysis and

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oxidation, thereby producing an unappealing soapy taste or rancid aroma. Heat treatments occur in a process known as kilning, where steam is used to denature enzymes, and then followed by drying or roasting, all of which enhance the stability of groats (Stewart and McDougall 2014). The kilning prevents oat products from retaining flat, greenish, or slightly bitter characteristics. It also provides distinctive flavors for oat products developed during heat processing of the groats, in addition to antioxidant compounds through the well established Maillard reaction and further interaction with lipids (Klensporf and Jeleń 2008).The kilning process has been shown to reduce by up to 40% the content of heat-labile B-vitamins but the benefits of the ability of kilning to extend shelf life far outweigh these undesirable effects (Arendt and Zannini 2013). Groats that have been kilned are known commercially as KDHO (Kiln Dried Hulled Oats) or cooked groats, and may be stored or further processed. Alternative methods are superheat steam (110°C–130°C) processing and microwave heating to similar effect but are more energy efficient (Rasane et al. 2013).

7.2.5 Cutting and Flaking After kilning, dried groats are subjected to cutting using a rotary granulator and stationary knives mounted outside the lower half of the drum. Different sizes of cut oats are sorted using sifters, followed by the removal of residual fine and hull pieces using an aspirator (Girardet and Webster 2011). To initiate flaking, steam is added to whole or steel cut oat groats to increase their moisture content by 5% and then soften the kernel so that they can form flakes with minimum shattering. The steaming process (99°C–104°C) also completes the inactivation of undesired enzymes and flavor characteristics. The actual flaking steps involve rolling, drying, and cooling with air to about 45°C and moisture content of approximately 9%–11.5% (Rasane et  al. 2013). Intact groats produce rolled oats while steel-cut ones produce flakes. Sifting is performed to remove fine and oversized flakes. The flake thickness determines the applications; whole rolled oats (0.508–0.762 mm), quick oats (0.356–0.457 mm), and instant oats (0.279–0.33 mm) (Menon et al. 2016).

7.2.6 Milling Kiln dried hulled oats, or rolled oats, can be converted into flours using an impact-type hammer mill where exhaust air is drawn through the system to prevent the relatively high fat oat flour sticking to the sides of the mill. After exiting the mill, the flour goes through a vibrating shifter to separate the anatomical parts of the grain into oat bran (coarse fraction), mostly from the outer aleurone and sub-aleurone layers of the groat, and flour without bran (fine fraction) (Wang et al. 2007; Decker et al. 2014). The American Association of Cereal Chemists has provided a definition of oat bran for consistency and practicability. That definition is: “Oat Bran is the food which is produced by grinding clean oat groats or rolled oats and separating the resulting oat flour by sieving bolting, and/or other suitable means into fractions such that the oat bran fraction is not more than 50% of the original starting material and has a total betaglucan content of at least 5.5% (dry-weight basis) and a total dietary fiber content of at least 16.0% (dry-weight basis), and such that at least one-third of the total dietary fiber is soluble fiber” (Cereal 1989). Drum drying of oats is a process where rolled

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oats are milled and mixed with water. The oat slurry is applied to steam-heated rotating rollers and the thin film produced is milled and used, for example, in instant baby foods (Bryngelsson et al. 2002).

7.3 Product Development Whole groats, steel-cut groats, and flours of oats are used in a variety of products. Demand for oat-based products has been increasing due to knowledge about oats’ nutritional benefits. Oats have been used to make foods such as porridge, oatmeal, muesli, granola bars, oat flour, oat bread, biscuits and cookies, oat milk, oat based probiotic drinks, breakfast cereals, flakes, and infant foods (Table 7.1). Oats are considered as suitable for someone with celiac disease, a condition related to the inability to properly digest gluten, and for this reason, they have been used to prepare gluten-free products (Holm et al. 2006; Ballabio et al. 2011). Specially formulated oat products containing varying proportions of (1→3) and (1→4)-β-glucans in addition to amylodextrins, small quantities of lipids, proteins, and minerals have been developed (Suyong Lee et al. 2005). These products (Table 7.1), called Oatrim, Nutrim, and C-Trim, are used as thickening agents or shortening in other food products (Harris and Smith 2006). An added advantage of oats as a food ingredient is that their main protein globulins and avenins are less likely to cause allergies (Rashid et al. 2007). The lack of gluten prevents oat flour from being used as the sole flour in raised breads, because gluten produces the needed elasticity and structure to bread dough that allow it to properly rise.

TABLE 7.1 Examples of Derived Products from Oats and Their Application Products/Brand

Description

Oatrim

Oat fiber

Nutrim

Oat fiber

C-Trim Adavena®

Oat fiber Oat bases rich in fiber

Oatly®

Oat bases rich in fiber

Proviva® Whole Grain Probiotic Liquid® SOYosa®

Oatmeal gruel, malted barley Malted oats, and other cereals

Yosa®

Oat

Jovita Probiotisch®

Blend of cereals

Oat and soy

Application Bakery, creaming agents and fat replacers (Mohamed et al. 2008) Bakery, creaming agents and fat replacers (Mohamed et al. 2008) Fat replacer, bakery, yoghurts, drinks Nondairy, yoghurt analogue (Mårtensson et al. 2002) Nondairy, yoghurt analogue (Mårtensson et al. 2002) Oat-based drink Drinks Drinks and probiotic yoghurt like soy–oat product (Siro et al. 2008) Probiotic yoghurt like oat product (Siro et al. 2008) Fruits and probiotic yoghurts

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135

7.3.1 Oatmeal and Breakfast Cereals Oats are more commonly consumed worldwide in the form of oatmeal. Primary markets are North America, the United Kingdom, and Northern Europe. Different types of oatmeal are available at grocery stores including regular, quick-cooking, and instant. Oat flakes are mainly used in the manufacturing of hot cereal breakfast. The presentation time of quick-cooking oatmeal, also referred to as instant flakes, is short, and their starches absorb more water. This is because the size of their flakes is thinner than those of regular oatmeal. Nutritional properties are often improved by fortifying instant oat products with vitamins and minerals. They are convenient, come in a variety of flavors, and differ in texture. Whole oat flakes retain identity and texture and exhibit the inherent characteristics of the gum (i.e. glucans). Hot cereal can be prepared by adding flakes to hot water or to cold water followed by heating. The texture is grainy when added to hot water, while the flakes have a creamy texture when added to cold water and then heated (Lapveteläinen and Rannikko 2000). Some modifications have been proposed to the process of obtaining flakes. For example, breakfast cereals made with germination oats had good texture and sensory properties and were stored at 23°C for up to 12 months without any degradation (Kince et al. 2017). Ready-to-eat (RTE) or cold cereals are the second major oat products. They include granola, muesli, and the traditional flaked and expanded products. RTE cereals can be produced using the extrusion technique. During the process, the grain is subjected to low moisture, high shear, and high temperature for a short time, after which the relief of pressure and reduction in temperature causes moisture to flash off and produce an expanded product (Brahma et al. 2016). Whole oat flour and oat bran are the most notable ingredients used in the production of RTE cereals. In certain cases, oat brans are blended with other cereals such as corn to increase the nutritional value (Liu et al. 2000). The duration of cooking, drying method, and final moisture content all affect the stability of RTE cereals because they are susceptible to oxidative rancidity (Webster 2011). Oats contain potent antioxidant molecules but depending on the process they can be overwhelmed. Oats are also used to make products such as granola and snack bars. Puffed snacks made by the extrusion process usually have low density and are marketed as low calorie, high fiber, and high protein nutritional products (Han et al. 2008).

7.3.2 Fermented Products and Drinks Fermentation can be used as an efficient and economical method to produce and preserve food but also as a technique to produce foods with better texture or nutritional values (Blandino et al. 2003). The majority of probiotic foods on the market are dairy products but alternatives are sought to help people who are allergic to milk proteins or have severe lactose intolerance. The food industry uses the fermentation technique to manufacture quality functional foods and drinks from oats and other cereals. Fermented oatmeal soups that contain viable lactic acid bacteria were reported as suitable for enteral nutrition and improved gut health (Marklinder and Lönner 1992). Adavena® and Oatly® are two fiber-rich products developed using enzymatic processes that have been reported to lower cholesterol but they have also been fermented into nondairy yoghurts (Mårtensson et al. 2002).

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Cereals in general contain good substrates for the proliferation of probiotic lactic acid bacteria, although the overall quantity of readily fermentable carbohydrates is less compared to milk (Charalampopoulos et al. 2002). The fermentation of cereals is also a way to create new functionalized foods and drinks (Laine et al. 2003; Patel et al. 2004). Oats have been in the development of probiotic foods. In this regard, Bacillus lactis incorporated into oat-based cereal bars were detected in feces of healthy human volunteers after consumption of the bars indicating that formulated oat products were a possible means of administering probiotics (Ouwehand et al. 2004). Oat bran and spent was also used to cultivate probiotic bacteria in a solid state (Patel et al. 2004). A drink that contained about 0.36% glucans was prepared by fermenting whole oat grains. The shelf life of the drink was 21 days when stored in a refrigerator (Angelov et al. 2006). Malted oats are used in the production of beer. The beverage industry uses them mainly as flavor adjuncts in the production of special lagers, ales, and stouts (Klose et al. 2009; Kordialik-Bogacka et al. 2014). The initial malting step defines the quality and type of beer through enzymatic degradation of cell walls surrounding starch granules and the degradation of the proteinaceous matrix surrounding the granules into soluble peptides and amino acids (Klose et al. 2009). Malting has also been used to reduce phytate, thereby enhancing the bioavailability of minerals.

7.3.3 Bakery and Pasta Products Bread is an important part of a daily diet for a vast population throughout the world and is mainly made using wheat because it contains the right amount of proteins with viscoelastic properties. Meanwhile, other cereals have been used for bread preparation for various reasons, including reduced immunoreactivity. Oats have been used to make breads with pleasant flavor and excellent moisture retention (Flander et al. 2007), while the addition of oat lecithin to wheat bread retarded the rate of staling (Zhang et al. 1998). Oats together with amaranth at a ratio of 1:3  were used to prepare gluten-free cookies and pasting viscosity, color, and sensory characteristics were similar to amaranth flour alone, and the authors concluded that the addition of oats was a good way to increase the nutritional quality of the amaranth flour (Inglett et al. 2015). Nutrim-5, a hydrocolloidal product, prepared by the thermomechanical processing of oat flour or bran at 10% concentration creates Asian noodles with acceptable texture and cook time (Inglett et al. 2005). C-TRIM, another β-glucan-rich fraction was used to increase soluble fiber content of bread made with hard red spring wheat flour (Mohamed et al. 2008). Pasta is a carbohydrate-based food that is mainly made with wheat and contains about 70% starch. Oats were used to prepare pastas with similar sensory quality compared to wheat, but in addition, they possessed low glycemic index (Hager et al. 2013). Oat bran was used to increase fiber and unsaturated fatty contents of bread (Beccerica et al. 2011). Muffins are common snacks and they have been baked using oat flours and brans alone or with oats supplemented to wheat or rice flours to decrease glycemic index (Soong et al. 2015). One study reported an increase in cooking loss of noodles and a negative effect on noodles containing 20%–40% oat flour but not in those with 10% oat flour (Aydin and Gocmen 2011). Spaghetti based on oats was successfully manufactured using two carboxymethylcellulose and pregelatinized starches (Chillo et al. 2009).

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7.3.4 Fat Replacers Texture, flavor, and appearance are the main quality attributes of many foods. The contribution of fat to these attributes leads to a more pleasant mouth feel in certain foods. The daily amount of fat eaten should fall within the recommended guidelines, but this is not always the case. Excess fat is associated with various health problems, including obesity and cardiovascular diseases. Reducing fat in the daily diet is then a public health issue and a concern for most consumers. Strategies have therefore been developed to reduce fat content of some foods while maintaining acceptable sensory characteristics. Substances based on carbohydrates or proteins have been used in some foods to mimic the functional and sensory properties of fat while providing considerably fewer calories (Zoulias et al. 2002). Oat products containing high fiber, including Oatrim, concentrated bran that contains dextrines and g1ucans, have applications as fat substitutes (Table 7.1). They can stabilize a substantial amount of water in a gel-like matrix, resulting in smooth and flow properties similar to those of fats. Replacement of up to 50% of fat by oat β-glucan and amylodextrins resulted in cookies that were similar to the fullfat ones (Inglett et al. 1994). They have been used in other products, including meat products, dairy, mayonnaise, and bakery products (Shen et al. 2011). The addition of hydrolyzed beta-glucans to 10% fat meatballs had no effect on texture, viscosity, or other characteristics, demonstrating their potential as fat replacer in meatballs (Liu et al. 2015), and patties formulated with oat gum were reported to have acceptable qualities (Dawkins et al. 2001). Cakes prepared by substituting up to 20% fat with oat-formulated polysaccharides had physical properties similar to those in the control cake, but at higher concentrations. But at higher oat contents, cakes displayed higher starch gelatinization temperatures due to the amylodextrins in the oat formulation (Suyong Lee et al. 2005). Another study showed that shortening in cakes could be substituted up to 40% by the beta-glucan hydrocolloidal composite called Nutrim without loss of quality (Lee et al. 2004). The elasticity and cohesiveness of control cheeses (11.2% fat) and oat fiber-substituted ones (6.8% and 3.5% fat) were similar but the substitution of fat improved their qualities by reducing hardness, fracturability, and melt-flow-time index, and this was due to the water-binding properties of the oat fibers (Konuklar et al. 2004). Negative effects of oat fibers characterized by greater heights, reduced spreads, and increased moisture loss were reported in cookies made by substituting 50% fat (Wekwete and Navder 2008).

7.4 Nutritional Aspects and Health Benefits Oats are an important source of many essential nutrients and have many unique health benefits in comparison to other whole grain cereals (Table 7.2). They are low in starch (27.3%–50.0%), high in fiber (13.6%–30.2%) and protein (9.7%–17.3%), as well as in poly- and monounsaturated fatty acids (5.2%–12.4%) (Sterna et al. 2016). They are also high in vitamin E, and in phytochemical compounds including avenanthramides, a group of polyphenols that is unique to oat cereals. These polyphenols give oats their antioxidant, anti-inflammatory, and anticarcinogenic properties. Oat proteins have high potential to act as antioxidants, through free radical scavenging, chelating of transition metals, and through the activation of endogenous antioxidant enzymes (Table 7.2).

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TABLE 7.2 Health Benefits of Oat Components Component β-Glucan

Protein

Peptides Avenanthramides

Effect

Test Methods

Reduced hyperglycemia through increased immune response

Hyperglycemic mice; healthy humans

Reduced plasma cholesterol

Human models; rat models

Anticancer

Mice mammary and hepatic tumors in vitro cancer cells Mouse model

Enhanced efficacy of antitumor antibody treatments Decreased cancer cell viability Decreased blood cholesterol and LDL levels Protected cells against ROS; increased endogenous antioxidant enzymes Inhibited cancer cell proliferation Antioxidant activity (scavenge radicals, upregulate enzymes, prevent lipid oxidation) Reduced inflammation through prevention of pro-inflammatory cytokines

In vitro models

Human colon cancer cells Chemical assays

Reference Bhatia and Dhillon (2007), Wang and Ellis (2014), Wood et al. (1994) Butt et al. (2008), Oda et al. (1993), Guo et al. (2014), Ryan et al. (2007), Ellegård and Andersson (2007) Hong et al. (2003)

Choromanska et al. (2015) Guo et al. (2014), Tong et al. (2016) Laughton et al. (1991), Díaz et al. (2003), Du et al. (2016) Guo et al. (2010) Fagerlund et al. (2009)

Guo et al. (2008, 2014), Yang et al. (2014)

High concentrations of soluble fibers, including β-glucan, has been proven to have positive effects on blood cholesterol, making oats the first whole grain cereal to be classified as “cholesterol-lowering.” Although oats have a higher lipid content than any other cereal (average of 3%–11% lipids), oat lipids are considered high quality due to the high levels of polyunsaturated fatty acids (linolenic and linoleic acids), monounsaturated fatty acids (oleic acid), and low levels of saturated fatty acids (steric and palmitic acid) (Zhou et al. 1999; van den Broeck et al. 2015). Together with the soluble fiber, oat lipids are associated with a decreased risk for many cardiovascular diseases (CVD), type 2 diabetes mellitus, and obesity (Austin 1989; Mensink and Katan 1989). The benefits have been evaluated in foods made with whole oat grains or formulated with oat bran or oat fibers. The consumption of oatmeal, for example, suppresses appetite, increases satiety, and reduces energy intake compared to oat-based ready-to-eat cereal (Rebello et al. 2016), while a food product containing fermented liquid oat bran and milk reduced the postprandial blood glucose response as efficiently as yoghurt after a high-glycemic index white wheat bread meal (Lindström et al. 2015). Many compounds are responsible for the benefits and the next sections will focus on their roles. Whole oats can protect humans against various disorders through their effects on the colon, blood glucose, triglycerides, redox balance, or immune system.

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7.4.1 Nutritional Value and Biological Effect of Oat Proteins Oats contain the highest concentration of protein of all whole grain cereals and they are composed of globulins (50%–80%), albumins (1%–12%), prolamins (4%–15%), and glutenins (25 g of dietary fiber per day for the average adult (WHO 2003). On average, a 100 g serving of oats contains 20–30 g of fiber (Daou and Zhang 2012), which would satisfy the daily recommended intake. Studies have shown the beneficial effect of oat glucans on the cardiovascular system (Table 7.2) because of their ability to lower blood LDL-cholesterol, circulating triglycerides, reduce inflammation, or prevent endothelial dysfunction in various models including human (Ellegård and Andersson 2007; Ryan et al. 2007; Guo et al. 2014). Beta-glucans increase the viscosity within the intestine, thus slowing gastric emptying and the absorption of both glucose and cholesterol into the bloodstream. The high viscosity also carries a greater quantity of bile acids further down the intestinal tract because they are unable to be in contact with transporters on the membrane and cannot then return to the liver through enterohepatic circulation. Furthermore, when β-glucans are digested in the gastrointestinal tract, they are broken down to shortchain fatty acids, such as propionic acid, butyrate, or acetate, which are absorbed into the bloodstream and can decrease synthesis of cholesterol in the liver (Drzikova et al. 2005). Oat glucans also work by inhibiting the expression of fatty acid synthases, thereby decreasing the amount of free fatty acids (Peng et al. 2013). Oat β-glucans are also able to help manage type 2  diabetes mellitus, a clinical disorder where patients suffer from hyperglycemia after meals because of a lack of sufficient secretion. By slowing the gastric emptying, they prolong the absorption of glucose, reducing the immediate insulin response (Wood et al. 1994).

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The addition of oat glucans to drinks of healthy individuals consuming 50 g of glucose dependently reduced plasma glucose and insulin levels. The effect was attributed to the increased viscosity of the drink because the reduction of the viscosity of glucans by acid hydrolysis reduced or eliminated the capacity to decrease postprandial glucose and insulin levels (Wood et al. 1994). Studies have also shown that an increase in oat dietary fibers, either through supplementary administration of oat β-glucans or through an increase of β-glucan in the diet are associated with a lower postprandial satiety levels in humans, which can be useful in the management of bodyweight (Howarth et al. 2001; Lyly et al. 2009). An anticancer mechanism has been proposed by Hong et al. (2003), stating that the administration of β-glucan isolate along with antitumor antibodies significantly improves the tumor suppression ability of the antibodies in mice (Table 7.2), and this could improve the efficacy of current antitumor and anticancer treatments. Another anticancer mechanism of β-glucans is through the activation of immune cells, such as leukocytes and monocytes (Demir et al. 2007).

7.4.3 Biological Effects of Oat Phytochemicals Phytochemicals present in oats are mostly phenolic acids and their derivatives, and smaller amounts of flavonoids. They are typically found in the bran layer of oats, and can include avenanthramides, vanillin, p-coumeric, ferulic acid, vanillic acid, syringic acid, sinapic acid, and p-hydroxybenzoic acid (Emmons et al. 1999; Chen et al. 2004). Avenanthramides are derivatives of anthranilic acid and hydroxycinnamic acid, and are unique to oats (Chen et al. 2004; Ratnasari et al. 2017). Phenolic compounds in oats like in other foods are associated with many health benefits due their antioxidant, anti-inflammatory, and anticarcinogenic effects. Mechanisms by which oats have antioxidant effects are quenching of radicals, metal chelating, and inhibition of oxidoreductases (Hitayezu et al. 2015; Ratnasari et al. 2017). Polyphenols can enhance endogenous antioxidant enzymes, possibly through the up-regulation of genes (Sang and Chu 2017). Avenanthramides have anti-inflammatory properties characterized by the inhibition pro-inflammatory cytokines, specifically interleukin-6, interleukin-8, and monocyte chemoattractant protein-1 in human aortic endothelial cells or the inhibition of tumor necrosis-alpha induced nuclear factor-κB activation (Guo et al. 2008; Yang et al. 2014). Oat polyphenols can also prevent inflammation by inhibiting the activity of lipoxygenase thereby reducing the formation of pro-inflammatory prostaglandins from oxidation of arachidonic acid (Ratnasari et al. 2017). Avenanthramides can provide systemic protection from oxidative stress because in a study on the plasma of individuals that consumed an enriched mixture extracted from oats they detected an association with high concentrations of reduced glutathione (Chen et al. 2007). Oat polyphenols may have antitumor activities as avenanthramides enriched extracts inhibited the proliferation of various colorectal adenocarcinoma cells such as HT29, Caco-2, and LS174T, and HCT116 lines possibly through the through the inhibition of macrophage prostaglandin E2 production (Guo et al. 2010). Overall, oats have high nutritional content, with high levels of protein and fiber, high concentration of mono- and polyunsaturated fatty acids, low levels of saturated fatty acids, and many polyphenolic compounds. Besides providing the body with necessary nutrients, each component has their own health benefits.

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7.5 Conclusion This chapter covers processing of oats, their use in product development, nutritive values, and the health benefits of whole oat products, fractions, and purified constituents. The processing of oats starts with the harvesting of kernels, storage, cleaning, dehulling, and kilning (heat treatment). They are then cut and flaked but are also milled to produce oat flour. The most common oat products are oatmeal, granola, muesli, and various ready-toeat breakfast cereals. However, oats are also used in the production of nondairy yoghurts, oat milk, beer, and oat probiotic drinks. Various oat components can be separated from the oat matrix and used as a food additive. For example, oat glucans and enriched brans are used as fat replacers or creaming agents in bakery products. Oat components, including glucans, peptides, and polyphenols, have antioxidant, anti-inflammatory, anticancer, antihypertensive, cholesterol lowering, and antidiabetic properties.

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Vasanthan, T., and R. S. Bhatty. 1995. “Starch Purification After Pin Milling and  Air  Classification of Waxy, Normal, and High Amylose Barleys.” Cereal Chemistry. Vasanthan, T., and F. Temelli. 2008. “Grain Fractionation Technologies for Cereal BetaGlucan Concentration.” Food Research International 41 (9): 876–81. doi:10.1016/j. foodres.2008.07.022. Wang, F., G. Yu, Y. Zhang, B. Zhang, and J. Fan. 2015. “Dipeptidyl Peptidase IV Inhibitory Peptides Derived from Oat (Avena Sativa L.), Buckwheat (Fagopyrum Esculentum), and Highland Barley (Hordeum Vulgare Trifurcatum (L.) Trofim) Proteins.” Journal of Agricultural and Food Chemistry 63 (43): 9543–49. doi:10.1021/acs. jafc.5b04016. Wang, Q., and P. R. Ellis. 2014. “Oat β-Glucan: Physico-Chemical Characteristics in Relation to Its Blood-Glucose and Cholesterol-Lowering Properties.” British Journal of Nutrition 112 (S2): S4–13. doi:10.1017/S0007114514002256. Wang, R., A. A. Koutinas, and G. M. Campbell. 2007. “Dry Processing of Oats Application of Dry Milling.” Journal of Food Engineering 82 (4): 559–67. doi:10.1016/j.jfoodeng.2007.03.011. Webster, F. H. 2011. “Chapter 17: Oat Utilization: Past, Present, and Future.” In OATS: Chemistry and Technology, 2nd edition, 347. Grain Science References. AACC International. doi:10.1094/9781891127649.017. Wekwete, B., and K. P. Navder. 2008. “Effects of Avocado Fruit Puree and Oatrim as Fat Replacers on the Physical, Textural and Sensory Properties of Oatmeal Cookies.” Journal of Food Quality. doi:10.1111/j.1745-4557.2008.00191.x. White, E. M. 1995. “Structure and Development of Oats.” In The Oat Crop: Production and Utilization, edited by R. W. Welch, 88–119. London, UK: Chapman & Hall. WHO. 2003. “Diet, Nutrition and the Prevention of Chronic Diseases.” World Health Organization Technical Report Series 916: i–viii-1-149-backcover. (NLM classification: QU 145). Wood, P. J., J. T. Braaten, F. W. Scott, K. D. Riedel, M. S. Wolynetz, and M. W. Collins. 1994. “Effect of Dose and Modification of Viscous Properties of Oat Gum on Plasma Glucose and Insulin Following an Oral Glucose Load.” The British Journal of Nutrition 72 (5): 731–43. doi:10.1079/BJN19940075. Wu, G.. 2009. “Amino Acids: Metabolism, Functions, and Nutrition.” Amino Acids 37 (1): 1–17. doi:10.1007/s00726-009-0269-0. Yang, J., B. Ou, M. L. Wise, and Y. Chu. 2014. “In Vitro Total Antioxidant Capacity and Anti-Inflammatory Activity of Three Common Oat-Derived Avenanthramides.” Food Chemistry 160: 338–45. doi:10.1016/j.foodchem.2014.03.059. Yao, N., J.-L. Jannink, S. Alavi, and P. J White. 2006. “Physical and Sensory Characteristics of Extruded Products Made from Two Oat Lines with Different Beta-Glucan Concentrations.” Cereal Chemistry 83 (6): 692–99. doi:10.1094/ CC-83-0692. Yu, G., F. Wang, B. Zhang, and J. Fan. 2016. “In Vitro Inhibition of Platelet Aggregation by Peptides Derived from Oat (Avena Sativa L.), Highland Barley (Hordeum vulgare Linn. Var. Nudum hook. F.), and Buckwheat (Fagopyrum esculentum Moench) Proteins.” Food Chemistry 194: 577–86. doi:10.1016/j. foodchem.2015.08.058. Zhang, D., W. R. Moore, and D. C. Doehlert. 1998. “Effects of Oat Grain Hydrothermal Treatments on Wheat-Oat Flour Dough Properties and Breadbaking Quality.” Cereal Chemistry. doi:10.1094/CCHEM.1998.75.5.602.

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Zhang, H., G. Onning, R. Oste, E. Gramatkovski, and L. Hulthen. 2007. “Improved Iron Bioavailability in an Oat-Based Beverage: The Combined Effect of Citric Acid Addition, Dephytinization and Iron Supplementation.” European Journal of Nutrition 46 (2): 95–102. doi:10.1007/s00394-006-0637-4. Zhou, M., K. Robards, M. Glennie-Holmes, and S. Helliwell. 1999. “Oat Lipids.” Journal of the American Oil Chemists’ Society 76 (2): 159–69. doi:10.1007/s11746-999-0213-1. Zoulias, E. I., V. Oreopoulou, and C. Tzia. 2002. “Textural Properties of Low-Fat Cookies Containing Carbohydrate- or Protein-Based Fat Replacers.” Journal of Food Engineering. doi:10.1016/S0260-8774(02)00111-5.

8 Quinoa S.S. Arya and Kakoli Pegu CONTENTS 8.1 8.2

8.3

Introduction .................................................................................................... 152 Processing ...................................................................................................... 153 8.2.1 Processing of Dried Edible Quinoa Product ..................................... 153 8.2.1.1 Preconditioning/Desaponification ..................................... 153 8.2.1.2 Moist Heating..................................................................... 154 8.2.1.3 Dry Heating ....................................................................... 154 8.2.2 Processing of Sweet Quinoa Product ................................................ 154 8.2.2.1 Preconditioning/Desaponification ..................................... 155 8.2.2.2 Conditioning ...................................................................... 155 8.2.2.3 Germination ....................................................................... 155 8.2.2.4 Incubation........................................................................... 155 8.2.2.5 Conversion and Reduction ................................................. 155 8.2.3 Preparation of Quinoa Milk .............................................................. 155 8.2.3.1 Wet Milling ........................................................................ 155 8.2.3.2 First and Second Separation .............................................. 155 8.2.3.3 Pasteurization ..................................................................... 156 8.2.3.4 Filtration and Blending ...................................................... 156 8.2.3.5 Ultra-High-Temperature (UHT) Processing ...................... 156 8.2.4 Effect of Processing on the Nutritional Components of Quinoa ...... 156 8.2.4.1 Abrasive Dehulling ............................................................ 156 8.2.4.2 Drying ................................................................................ 156 8.2.4.3 Milling ............................................................................... 157 8.2.4.4 Cooking .............................................................................. 158 8.2.4.5 Fermentation ...................................................................... 159 Product Development ..................................................................................... 159 8.3.1 Bakery Products ................................................................................ 159 8.3.1.1 Bread .................................................................................. 159 8.3.1.2 Cookies .............................................................................. 160 8.3.1.3 Cakes and Muffins ............................................................. 160 8.3.1.4 Extruded Products.............................................................. 160 8.3.2 Beverages ........................................................................................... 161 8.3.3 Miscellaneous .................................................................................... 161

151

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8.4

Nutritional Properties..................................................................................... 162 8.4.1 Proteins .............................................................................................. 162 8.4.2 Carbohydrates .................................................................................... 162 8.4.3 Lipids ................................................................................................. 163 8.4.4 Vitamins and Minerals ...................................................................... 164 8.4.5 Antioxidants ...................................................................................... 164 8.4.6 Antinutritional Factors ...................................................................... 165 8.4.6.1 Saponins ............................................................................. 165 8.4.6.2 Phytic Acid ......................................................................... 165 8.5 Health Benefits ............................................................................................... 165 8.5.1 Celiac Disease ................................................................................... 165 8.5.2 Cardiovascular Disease ..................................................................... 166 8.5.3 Improvement of Health Status in Children ....................................... 166 8.5.4 Post Menopause ................................................................................. 166 8.5.5 Diabetes ............................................................................................. 167 8.6 Conclusions and Future Trends ...................................................................... 167 References ................................................................................................................ 167

8.1 Introduction Quinoa (Chenopodium quinoa Willd.) belongs to family of Chenopdiaceae and is one of the native food plants of the Andean region of South America (Vega-Gálvez et al., 2010), with cultivation dating back to 5000 BC (Repo-Carrasco et al., 2003), as evidenced by archaeological findings (Ando et al., 2002; Jancurová et al., 2009). It was appreciated for its high nutritional value by the Incas (who named it “mother grain”) (Ando et al., 2002), and the ease in milling these crops made it possible for the rural populations to take advantage of its nutritional value. Quinoa was often chosen as a substitute when there was a dearth of animal protein and is still one of the main protein sources in such areas (Repo-Carrasco et al., 2003). The year 2013 was declared as the International Year of Quinoa by the United Nations. FAO (2011) reported that the main producers of quinoa are Bolivia, Peru, the United States, Ecuador, and Canada. Quinoa is also cultivated in England, Sweden, Denmark, the Netherlands, Italy, and France. Until 2008, production in Peru and Bolivia accounted for 90% of the world quinoa production. Following them are the United States, Ecuador, and Canada with about 10% of global production volumes. Quinoa cultivation is expanding because it has a high potential both for its nutritional benefits and its agricultural versatility to contribute to food security in various countries. In recent years (2009), production in the Andean Region was about 70,000 tonnes with almost 40,000 tonnes produced by Peru, 28,000 tonnes by Bolivia, and 746 tonnes by Ecuador. Bolivia is the largest exporter of quinoa in the world followed by Peru and Ecuador. In 2009, Bolivia exported a value of over US$43 million. The major importers of Bolivian quinoa grain are: the United States (45%), France (16%), the Netherlands (13%), Germany, Canada, Israel, Brazil, and the United Kingdom. The quinoa seed has a disc-shaped structure, with a diameter of about 2 mm, and a thickness of 0.5 mm. The major anatomical parts of the grain are the pericarp, the

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153

FIGURE 8.1 Longitudinal section of quinoa seed. (From Burrieza, H.P. et al., Front. Plant Sci., 5, 546, 2014; Graf, B.L. et al., J. Sci. Food Agric., 96, 633–643, 2016; Prego, I. et al., Ann. Botany, 82, 481–488, 1998.)

perisperm, and the embryo. The pericarp (bran) usually contains bitter-tasting saponins, which are the major antinutritional compounds in quinoa. The embryo of the milled grain wraps around the perisperm “like a headband” and is rich in proteins and lipids (Ando et al., 2002), as shown in Figure 8.1. Starch grains, on the other hand, along with lipid and protein bodies, occupy much of the perisperm (Abugoch James, 2009).

8.2 Processing Quinoa has been processed into several products. The flowchart for processing of quinoa into various value-added products is shown in Figure 8.2.

8.2.1 Processing of Dried Edible Quinoa Product Dried edible quinoa product, called quinoa crisp, is produced by the cooking and dehydration of individual seeds that have the intact embryo and perisperm of the native quinoa grain and minimal volume expansion of starch. It is particularly used to add flavor and/or texture to bakery products, nutrition bars, granolas, confections, and chocolates. It can withstand additional and/or extreme food processing methods, e.g., retorting. It can be used as a replacement for allergenic nuts, seeds, and sesame seeds.

8.2.1.1 Preconditioning/Desaponification Desaponification of quinoa is used to remove or reduce bitter taste associated with saponin content in the pericarp of quinoa. Quinoa seed hulls contain high amounts (20%–30%) of saponins, which may be implicated to the plant’s natural defenses against bird, pest, and fungal attack (Gee et al., 1993; Stuardo and San Martín, 2008). About 86% of the total saponins were found to be concentrated in the bran (Ando et al., 2002). Quinoa saponins are removed by washing, abrasive dehulling, or a combination of the two (Jacobsen et al., 2003). By washing or soaking for 30 min, and 20 min

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FIGURE 8.2 Flowchart for processing of quinoa grain into various products. (From Evans, T.C. et al., (12) Patent Application Publication (10) Pub. No.: US 2006 / 0222585 A1 Figure 1, 002, 354, 2015.)

agitation at 70°C reduces saponin content down to 0.04%–0.25% (Domínguez, 2003). Alternatively, a Tangential Abrasive Dehulling Device (TADD) can be used to remove saponin by removing approximately 1%–15% from the seed surface. Evans et  al. (2015) performed preconditioning, which includes abrasion followed by an initial quick wash with stiffing, agitation, or spray or countercurrent extraction immediately followed by draining or centrifugation to minimize penetration of the water-soluble saponins into the seed coat.

8.2.1.2 Moist Heating Moist heating involves the treatment of preconditioned quinoa grain by steam cooking or pressure-cooking. The quinoa grain is heated and cooked for about 20–60 min until the individual grains are translucent.

8.2.1.3 Dry Heating After moist heating, the quinoa grains are heated in a dry environment, such as baking, toasting, and/or dehydrating. It includes an initial baking for 10  min at about 121.111°C followed by a second baking for 2 min at 287°C in a convection oven.

8.2.2 Processing of Sweet Quinoa Product Sweet quinoa product, flavored and/or sweetened, functions as a humectant in bakery products, nutrition bars, beverages, and coffee and tea products.

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155

8.2.2.1 Preconditioning/Desaponification Same as that of the preparation of quinoa crisp (Evans et al., 2015).

8.2.2.2 Conditioning Conditioning is a treatment to adjust the moisture content of the quinoa grain for the next step (germination). After preconditioning, clean water is added in different proportions, preferably 1:1 for about 160–260 min until the moisture content is about 35%–45% at ambient temperature.

8.2.2.3 Germination Germination is carried out at 10°C–11°C and the moisture content is maintained at about 35%–45% by circulation of air throughout the process of germination (48–72 h). The product of germination of quinoa grain is called “green quinoa malt.”

8.2.2.4 Incubation Water is added to the germinated sprout (ratio 3:1) and heated (32°C–42°C) for about 30–120 min so that the carbohydrate is released into the solution to form slurry.

8.2.2.5 Conversion and Reduction Conversion and reduction involve conversion of complex carbohydrates to simple carbohydrates by cooking under continuous agitation at 67°C–87°C for about 15–60  min. Cooking is followed by evaporation to reduce the water and condense the liquid slurry. It is dried to form sweet powdered quinoa product. The sweetness of the powdered product is higher than in edible sweet slurry, which does not include a reduction or condensation process.

8.2.3 Preparation of Quinoa Milk 8.2.3.1 Wet Milling The wet milling is performed using a colloid mill, which is a machine that reduces the particle size of a solid in suspension in a liquid, or to reduce the droplet size of a liquid suspended in another liquid. The particle size reduction is performed by applying high levels of hydraulic shear to the liquid. The colloid mill may also serve to increase the stability of suspensions and emulsions. Furthermore, the slurry may be combined with alkaline agents to adjust the pH to a desirable level (e.g., from 7.5 to 12.5).

8.2.3.2 First and Second Separation First separation is done by decanter, where the sediments precipitated are left in the original container. Then the decanted slurry is centrifuged for a second separation operating at about 2,500–3,500  rpm or higher for a predetermined period of

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time (30 s to 5 min) in order to further separate the starch and proteins (protein-tocarbohydrate ratio from 1:1.5 to 1:3).

8.2.3.3 Pasteurization Pasteurization is carried out at 79.444°C–101.667°C for at least 20 s or longer in order to cure the mixture.

8.2.3.4 Filtration and Blending Either nano- or ultrafiltration is used to retain the suspended solids and solutes of high molecular weight and concentrate the protein in the resultant slurry. The quinoa water is blended to provide flavor, masking, and/or whitening, if desired.

8.2.3.5 Ultra-High-Temperature (UHT) Processing The blended mixture is subjected to UHT processing for 1–3 s at a temperature above 135°C. Then it is homogenized and filled.

8.2.4 Effect of Processing on the Nutritional Components of Quinoa 8.2.4.1 Abrasive Dehulling On manual dehulling of whole quinoa seeds and washing to remove saponins, it was seen that dehulling significantly lowered the protein content from 17.41% to 15.69%, and a further, statistically not significant, reduction in seed protein was obtained by water extraction (15.16%), indicating the pronounced effect of dehulling. However, dehulling also led to a 2-fold decrease in the ash content, particularly in calcium and sodium contents (53% and 34% reduction respectively) (Stikic et al., 2012). The saponin content was quantitatively found to decrease with an increase in the degree of abrasive dehulling, which led to a decrease in the hemolytic activity in human blood. While the oil and protein contents of dehulled grains were minimal, up to 10% removal of kernel, overprocessing led to significant losses. Trials on large-scale abrasive dehullers, such as the PRL mini dehuller, indicated that the process can be scaled up effectively (Reichert et al., 1986).

8.2.4.2 Drying When washed, quinoa seeds were subjected to drying in a convective dryer at 40°C, 50°C, 60°C, 70°C, and 80°C, using a constant air flow rate of 2.0 ± 0.2 m s−1 until a constant weight (equilibrium condition) was obtained, the minimum and maximum drying times found were 150 min (at 80°C) and 420 min (at 40°C). The drying process led to a decrease of 10% and 12% in proteins and fat, respectively. Possible reasons for this protein loss have been ascribed to denaturation, changes in solubility, and reaction of released amino acids with sugars to form melanoidines by way of Maillard reaction, while the losses in lipids have been thought to be due to initial enzymatic hydrolysis and thermal degradation. A significant loss of sucrose (possibly due to hydrolysis) (56%) occurred at high drying temperatures (80°C) (Miranda et al., 2010).

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8.2.4.3 Milling After removal of saponins, the quinoa can be consumed as entire grains, or be processed in different ways (Repo-Carrasco et al., 2003). Quinoa can be milled to flour for bakery applications, noodles, soup, porridge, infant food, etc. (Jacobsen et al., 2003; Repo-Carrasco et al., 2003). Milling can be done to manufacture jiquira (quinoa semolina), jacku (raw flour), and quinoa flour (milled de-bittered quinoa seeds) (Repo-Carrasco et al., 2003), although much literature is not available to date on the former two products. When quinoa grains were polished, milled, and fractionated using a rice-milling machine, it yielded 8.2% bran, 30.1% embryo, and 58.8% perisperm (whole grainweight basis), with losses of 2.9%. While milling had little effect on the protein, lipid, sugar, dietary fiber, and ash contents as a whole, it was found that the embryo contributed more protein, lipids, and soluble dietary fiber, while the bran contained more insoluble dietary fiber, ash, and saponins than the rest of the fractions (Ando et al., 2002). The perisperm, on the other hand, contributed significantly to the carbohydrate content (Table 8.1). The effects of milling the whole grain on the mineral composition were not pronounced. While the embryo was regarded as a valuable source of oil, the phytate, trypsin inhibitor, and lipoxygenase activity were also found to be highest in the embryo (60%, 89%, and 62% of total activity, respectively). Flour from milled whole grain was found to have a stronger odor (like soybeans) than flour from only the perisperm, which was attributed to the tendency of lipoxygenase to oxidize the unsaturated fatty acids (Ando et al., 2002). When attempting to incorporate quinoa flour into different products, two problems may arise. The small diameter of starch granules results in a lower gelatinization temperature (similar to potato starch) and possible destabilization of dough, and a lower amylose content (11%–12% compared to 28% of wheat and maize) (Koziol, 1992) could affect retrogradation (Steffolani et al., 2013). These may limit the percentage of substitution that can be done with quinoa flour in conventional flours (Koziol, 1992).

TABLE 8.1 Contributions of Bran, Perisperm, and Embryo Towards the Proximate Composition of Quinoa Seeds g/100 g Proximate (Dry Basis) Proximate Protein Lipid Carbohydrate other than fiber Dietary fiber Soluble dietary fiber Insoluble dietary fiber Ash

Bran

Perisperm

Embryo

4 5 7 16 4 21 24

39 46 73 39 35 41 25

57 49 20 45 61 38 51

Source: Ando, H. et al., Food Sci. Technol. Res., 8, 80–84, 2002.

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8.2.4.4 Cooking Dini et al. (2010) studied the effect of cooking on antioxidant activity of quinoa seeds (bitter and sweet varieties). The quinoa seeds were boiled in water for 20 min (considered as the traditional cooking time), and the seeds and water were analyzed. It was found that when cooking, the phenolics content decreased significantly (p 20%) were rated to have a less crispy and crunchy texture, which was in synchronicity with measurements of porosity and wall thickness made using X-ray microtomography. Diaz and Jouppila (2013) reported that quinoa-based extrudates were less sensitive to oxidation, with amaranthbased snacks showing a considerable increase in hexanal production on increasing the storage temperature from 20°C to 40°C for 1 week of storage at 20%, 35%, and 50% replacement levels, such that by the end of the fifth week of storage at 40°C, extrudates containing 35% amaranth and 50% quinoa showed the highest hexanal content. When quinoa flour was used for replacing sour cassava starch, it had a positive effect on the hardness of the corresponding extruded product (Taverna et al., 2012). While pasta made from 100% quinoa flour tended to disintegrate shortly after the start of cooking and resulted in a soft texture compared to one made from Durum wheat, the properties were improved upon when a combination of amaranth, quinoa, and buckwheat flours were used in the ratio of 40:40:60 to prepare the dough, with the use of egg white powder (up to 6% of flour) and emulsifier DMG (distilled monoglyceride) (1.2% of flour) at optimum dough moisture (30%) (Schoenlechner et al., 2010a). When egg was omitted from the pasta formulation, the sensory acceptance was found to be just 61% for quinoa, compared to 87% and 82% for teff and buckwheat, respectively, while still being higher than that of amaranth (15%) (Kahlon et al., 2013). Use of 20% amaranth flour, 20% quinoa flour, and 60% buckwheat flour to prepare dough for pasta proved to give higher elasticity than that made from 70% millet flour and 30% white bean flour; the most probable reason for this was the higher cysteine content in quinoa and buckwheat, which induced exchange reactions between the contained thiol groups at higher drying temperatures. It was concluded that protein quality of flour was more important to pasta-making than the quantity (D’Amico et al., 2015).

8.3.2 Beverages In an attempt to prepare beer-like gluten-free beverage using Saccharomyces pastorianus strain TUM 34/70, it was found that quinoa took a longer time to ferment than barley, with only 44% of the quinoa wort being fermented. However, quinoa malt had a protein content close to twice that of barley and buckwheat, and higher mineral contents (iron, copper, zinc, and manganese), which may have been responsible for the low palatability scores for quinoa (Deželak et al., 2014). A raspberry-flavored functional beverage with a final protein content of 1.36%, meant for children aged 2–5 years was developed with mesquite, lupine, and quinoa, and was found to have acceptable color, viscosity, and suitability for consumption (Mezquita et al., 2012). During studies on the effect of substitution of soy with quinoa on physicochemical properties of resultant fermented beverages, it was found that its use led to a decrease in fermentation time, an increase in viscosity, and provided appropriate protein, carbohydrate, and lipid contents, besides providing a lower calorific value than when prepared with soy extract alone (Valcárcel-Yamani and Caetano, 2012).

8.3.3 Miscellaneous Some other food applications include potential use of quinoa in sausages (FernándezDiez et al., 2016), cereal bars (Farinazzi-Machado et al., 2012), breakfast cereals

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(Farinazzi-Machado et al., 2012; Medina et al., 2011), and weaning foods (Pathania et al., 2013; Repo-Carrasco et al., 2003; Ruales et al., 2002). Further, while quinoa leaves have not been discussed in this review, they too can be used in food applications such as salads, soups (Jacobsen et al., 2003), and breads (Gawlik-Dziki et al., 2015; Świeca et al., 2014), and for dietary supplementation (Gawlik-Dziki et al., 2013).

8.4 Nutritional Properties 8.4.1 Proteins Quinoa is considered to be a complete protein (Abugoch James, 2009), as it is a source of all ten strictly essential amino acids, namely lysine, isoleucine, leucine, phenylalanine, tyrosine, threonine, tryptophan, valine, histidine, and methionine (Vega-Gálvez et al., 2010). Further, quinoa protein has a biological value (BV) of 83%, a value that is higher than that of fish (76%), beef (74.3%), soybean (72.8%), wheat (64%), rice (64%), and corn (60%) proteins, but lower than that of whole egg (93.7%) and cow milk (84.5%) (Gonzalez et al., 2012). Table 8.4 summarizes the proximate composition of quinoa seeds. Albumins and globulins form the major protein fraction of quinoa (44%–77% of total protein), while prolamins constitute the minor fraction (0.5%–7.0%). Hence, quinoa is considered to be gluten-free, as it contains very little prolamin. This is particularly of relevance to people suffering from gluten intolerance (Valencia-Chamorro, 2016). However, this absence of gluten makes quinoa flour unsuitable for baking when used alone (Abugoch James, 2009; Thoufeek Ahamed et al., 1998). A comparison of the content of essential amino acids present in quinoa seeds to that of wheat, rice, and maize is presented in Table 8.5. It is seen that lysine, the limiting amino acid in many cereal grains, is present in quinoa seeds at a concentration of 1.6–2.3 times that of the other listed cereal grains.

8.4.2 Carbohydrates Starch is the major carbohydrate fraction in quinoa and is present at levels ranging from 60% to 70% (dry basis) (Steffolani et al., 2013), with a gelatinization temperature

TABLE 8.4 Proximate Composition of Quinoa Seeds Amount Present (g/100 g Dry Weight) Component

Koziol (1992)

Dini et al. (1992)

Roe et al. (2015)

Ferreira et al. (2015)

USDA (2016b)

Protein Fat Carbohydrate Fiber Ash

16.5 6.3 69.0 3.8 3.8

13.7 14.5 64.8 2.6 3.5

13.8 5.0 55.7 7.0 N.R.

23.9 8.3 62.3 N.R. 5.5

14.1 6.1 64.2 7.0 2.4

N.R. = Not reported.

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Amino Acid

Quinoa

Wheat

Rice

Maize

(Joint WHO/ FAO/UNU Expert Consultation, 2007)

USDA (2016b)

Dini et al. (1992)

Koziol (1992)

Koziol (1992)

Koziol (1992)

Koziol (1992)

1.5 3.0 5.9 2.2 3.8 2.3 3.9 4.5 0.6

2.9 3.6 5.9 3.6a 6.1a 3.0 4.2 5.4 1.2

2.0 7.4 7.5 4.5 7.5 3.5 6.0 4.6 N.R.

3.2 4.4 6.6 4.8 7.3 3.8 4.5 6.1 1.2

2.0 4.2 6.8 3.7 8.2 2.8 4.4 2.6 1.2

2.1 4.1 8.2 3.6 10.5 3.8 6.1 3.8 1.1

2.6 4.0 12.5 4.0 8.6 3.8 5.0 2.9 0.7

His Ile Leu Met + Cys Phe + Tyr Thr Val Lys Trp

Represents combined values of the individual amino acids. His = histidine; Ile = isoleucine; Leu = leucine; Met = methionine; Cys = cysteine; Phe = phenylalanine; Tyr = tyrosine; Thr = threonine; Val = valine; Lys = lysine; Trp = tryptophan; N.R. = not reported.

a

of 50°C–65°C (Hager et al., 2012; Jancurová et al., 2009; Lindeboom et al., 2005). The temperatures at onset, peak, and gelatinization for quinoa flour were reported to be 52°C, 58°C, and 64°C, respectively, and these values were found to be higher than for oats but lower than for wheat (Wolter et al., 2013). The amylose fraction in quinoa measures at just 3%–20% (Lindeboom et al., 2005; Qian and Kuhn, 1999; Steffolani et al., 2013), lower than that present in wheat (Lee and Won, 2000; Sestili et al., 2010), barley, sorghum, oats, maize, rye, pearl millet, and triticale, all of which have an amylose content of 21%–27.6% (Lee and Won, 2000).

8.4.3 Lipids Quinoa seeds contain 5.0%–14.5% oil on a dry weight basis, which is found to be lower than that of soybeans (20.9% dry basis) (Abugoch James, 2009). Broadly, the quinoa lipids contain 12.3%–19% total saturated, 25%–28.7% total monounsaturated, and 58.3% total polyunsaturated fat (James, 2009). The vitamin E content of quinoa seeds has been reported to be 2.6  mg/100  g (Ruales and Nair, 1993), which confers the oil stability, as vitamin E can act as a natural antioxidant (James, 2009; Ng et al., 2007; Valcárcel-Yamani and Lannes, 2012); in fact, minimal oxidation products were observed on 30 days of storage of quinoa (Ng et al., 2007). Squalene (a triterpenic hydrocarbon), tocopherols, and sterols are found to be a part of the unsaponifiable matter (5.2%) of quinoa seeds (Koziol, 1992). β-sitosterol, Δ7-stigmastenol, and Δ7-avenasterol were found to be the most abundant (27.2%, 51.3%, and 8.7% of total sterols, respectively).

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8.4.4 Vitamins and Minerals Table 8.6 presents a comparison of the mineral and vitamin contents of quinoa seeds with that of rice, barley, and wheat. The major minerals present are potassium, phosphorus, magnesium, and calcium, while the major vitamins are vitamins E and C. While the contents are generally higher than the other cereals, the phosphorus content of quinoa is close to that of rice, and quinoa seeds contain lower levels of thiamine and niacin compared to rice, barley, and wheat (Koziol, 1992). Magnesium, manganese, copper, and iron are present in sufficient concentrations so as to satisfy the daily needs of infants and adults, while the riboflavin content satisfies 80% of the daily requirements of children and 40% of that of adults for every 100  g consumed (Abugoch James, 2009). Dehulling can lead to significant losses in calcium and sodium (Stikic et al., 2012). The iron in quinoa may have a high bioavailability, being highly soluble, and could be beneficial to anemic patients (Vega-Gálvez et al., 2010). The calcium to phosphorus ratio (1:2.6) (Koziol, 1992) is higher than the recommended ratio of 1:1.5 (Ahamed et al., 1998).

8.4.5 Antioxidants A variety of phenolics and flavonoids have been detected in quinoa seeds. The former includes gallic acid (320 mg/kg), p-hydroxybenzoic acid (76.8 mg/kg), vanillic acid (43.4  mg/kg), caffeic acid (40  mg/kg), and cinnamic acid (10  mg/kg), while the latter include rutin (360  mg/kg), orientin (1076  mg/kg), vitexin (709  mg/kg), morin (88.9  mg/kg), hesperidin (1.86  mg/kg), and neohesperidin (1.93  mg/kg) TABLE 8.6 Contents of Major Minerals and Vitamins in Quinoa, Rice, Barley, and Wheat Grains mg/100 g Dry Basis (Mean Values) Mineral/Vitamin Potassium Phosphorus Magnesium Calcium Iron Sodium Manganese Copper Zinc Thiamin (B1) Riboflavin (B2) Niacin (B3) Ascorbic acid α-Tocopherol β-Carotene

Quinoa

Rice

Barley

Wheat

926.7 383.7 249.6 148.7 13.2 12.2 10.0 5.1 4.4 0.38 0.39 1.06 4.00 5.37 0.39

118.3 137.8 73.5 6.9 0.7 6.9 2.3 0.2 0.6 0.47 0.10 5.98 0 0.18 N.R.

502.8 387.3 129.1 43.0 3.2 20.3 1.9 0.3 3.5 0.49 0.20 5.44 0 0.35 0.01

578.3 467.7 169.4 50.3 3.8 8.9 3.9 0.7 4.7 0.55 0.16 5.88 0 1.15 0.02

Source: Koziol, M.J., J. Food Comp. Anal., 5, 35–68, 1992. N.R. = Not reported.

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(all on dry weight basis) (Paśko et al., 2008). The antioxidant activity of quinoa seeds was found to surpass that of amaranth (Paśko et al., 2008), rice, and buckwheat (Gorinstein et al., 2008).

8.4.6 Antinutritional Factors 8.4.6.1 Saponins Saponins, chemically steroids or tristeroid terpenoids (James, 2009), are bitter compounds present in the pericarp of quinoa seeds, and cause foaming in water (Jancurová et al., 2009). They are present at levels of 0.1%–5% (Valencia-Chamorro, 2016). However, in general, the sweet quinoa varieties are found to contain less than 0.11%, while the bitter varieties are found to contain more than 0.11% saponins (Vega-Gálvez et al., 2010). They are considered antinutritional, as they tend to form insoluble complexes with minerals like zinc and iron, rendering them unavailable for absorption by the body.

8.4.6.2 Phytic Acid Phytic acid (chemically myoinositol 1,2,3,4,5,6-hexakis dihydrogen phosphate) is found in most cereals and legumes at concentrations of 1%–3% dry matter (Jancurová et al., 2009), while the concentration in quinoa falls in the range of 1.05%–1.35% (Koziol, 1992). However, unlike cereals like rye and wheat, in quinoa, phytic acid is also present in the endosperm in addition to the outer layers (Vega-Gálvez et al., 2010). Phytates have the ability to complex with iron, zinc, calcium, and magnesium, and hence are antinutritional in nature (Ahamed et al., 1998).

8.4.6.2.1 Protease Inhibitors and Tannins In quinoa seeds, protease inhibitors such as trypsin inhibitors are present in quantities of less than 50 ppm, which is not sufficient enough to cause serious harm (Ahamed et al., 1998). Tannins, compounds that have the ability to complex with dietary proteins and digestive enzymes (Ahamed et al., 1998), constitute 0.051% of quinoa seeds on a dry weight basis (Gorinstein et al., 2008); however, these get removed on desaponification using abrasive dehulling and washing (Ahamed et al., 1998).

8.5 Health Benefits 8.5.1 Celiac Disease Zevallos et al. (2014) studied the in vivo gastrointestinal effects of consuming cooked quinoa in adults having celiac disease. Nineteen patients were made to consume 50 g quinoa/day for 6  weeks as part of their strict gluten-free diet, and detailed histological assessments of 10 patients were carried out before and after eating quinoa. Gastrointestinal parameters such as ratio of villus height to crypt depth, surfaceenterocyte cell height, the number of intra-epithelial lymphocytes per 100 enterocytes, and cholesterol (total, low-density lipoprotein [LDL] and high-density lipoprotein [HDL]) levels showed encouraging trends suggesting a mild hypocholesterolemic

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effect, and the ability of celiac patients to tolerate the addition of quinoa to their diet at 50 g per day for up to 6 weeks without aggravating the condition. However, while most quinoa cultivars were found to not possess quantifiable amounts of celiac-toxic epitopes, 2 out of the 15 cultivars studied (Ayacuchana and Pasankalla) had celiac-toxic epitopes that could activate the adaptive and innate immune responses in some patients with celiac disease, as shown by stimulated T cell lines and secretion of cytokines from cultured biopsy samples at levels comparable with those for gliadin (Zevallos et al., 2012).

8.5.2 Cardiovascular Disease Twenty-two (18–45-year-old) students were supplemented with quinoa (total 19.5 g quinoa per day) in the form of cereal bars for 30 days, and the effects of this inclusion in diet on the biochemical and anthropometric profile and blood pressure were investigated, being parameters for measurement of risk of cardiovascular diseases. Blood samples collected before and after the length of the treatment indicated that quinoa had beneficial effects on part of the population studied as the levels of total cholesterol, triglycerides, and LDL cholesterol reduced. It was concluded that the use of quinoa in the diet can be considered beneficial in the prevention and treatment of risk factors related to cardiovascular diseases (Farinazzi-Machado et al., 2012).

8.5.3 Improvement of Health Status in Children An infant food product was manufactured by drum-drying a precooked slurry of quinoa flour and was given to 40 boys of Ecuadorian families of low economic status aged 50–65 months. Evaluation of chemical composition of quinoa revealed the following values—protein (16), vitamin E (19 mg/kg), thiamine (0.7 mg/100 g), iron (70  mg/kg), zinc (48  mg/kg), and magnesium (1.8  g/kg) (all values on dry weight basis). Animal feeding experiments with rats showed a net protein utilization (NPU), digestibility, and biological value of 68, 95, and 71, respectively. It was seen that the plasma level of insulin-like growth factor-1 (IGF-1) of the children who consumed a supplementary portion of 2 × 100 g of the infant food product increased after a period of 15 days, while there was no such significant increase (p