Plant Proteins: Applications, Biological Effects, and Chemistry 9780841209763, 9780841211483, 0-8412-0976-6

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Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.fw001

Plant Proteins: Applications, Biological Effects, and Chemistry

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.fw001

ACS

SYMPOSIUM

SERIES

312

Plant Proteins: Applications, Biological Effects, and Chemistry Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.fw001

Robert L. Ory, EDITOR U.S. Department of Agriculture

Developed from a symposium sponsored by the Division of Agricultural and Food Chemistry at the 190th Meeting of the American Chemical Society, Chicago, Illinois, September 8-13, 1985

American Chemical Society, Washington, D C 1986

Library of Congress Cataloging-in-Publication Data Plant proteins. (ACS symposium series; 312) "Developed from a symposium sponsored by the Division of Agricultural and Food Chemistry at the 190th Meeting of the American Chemical Society, Chicago, Illinois, September 8-13, 1985."

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.fw001

Includes bibliographies and indexes. 1. Plant proteins as food—Congresses. 2. Food— Protein content—Congresses. 3. Diet—Congresses. 4. Proteins in human nutrition. I. Ory, Robert L., 1925. II. American Chemical Society. Division of Agricultural and Food Chemistry. III. American Chemical Society. Meeting (190th: 1985: Chicago, Ill.) IV. Series. TX392.A172 1986 ISBN 0-8412-0976-6

641.1'2

86-10848

Copyright © 1986 American Chemical Society All Rights Reserved. The appearance of the code at the bottom of the first page of each chapter in this volume indicates the copyright owner's consent that reprographic copies of the chapter may be made for personal or internal use or for the personal or internal use of specific clients. This consent is given on the condition, however, that the copier pay the stated per copy fee through the Copyright Clearance Center, Inc., 27 Congress Street, Salem, M A 01970, for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to copying or transmission by any means—graphic or electronic—for any other purpose, such as for general distribution, for advertising or promotional purposes, for creating a new collective work, for resale, or for information storage and retrieval systems. The copying fee for each chapter is indicated in the code at the bottom of the first page of the chapter. The citation of trade names and/or names of manufacturers in this publication is not to be construed as an endorsement or as approval by ACS of the commercial products or services referenced herein; nor should the mere reference herein to any drawing, specification, chemical process, or other data be regarded as a license or as a conveyance of any right or permission, to the holder, reader, or any other person or corporation, to manufacture, reproduce, use, or sell any patented invention or copyrighted work that may in any way be related thereto. Registered names, trademarks, etc., used in this publication, even without specific indication thereof, are not to be considered unprotected by law. PRINTED IN THE UNITED STATES OF AMERICA

ACS Symposium Series M . Joan Comstock, Series Editor

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.fw001

Advisory Board Harvey W. Blanch

Donald E. Moreland

University of California—Berkeley

U S D A , Agricultural Research Service

Alan Elzerman

W. H. Norton

Clemson University

J . T. Baker Chemical Company

John W. Finley

James C. Randall

Nabisco Brands, Inc.

Exxon Chemical Company

Marye Anne Fox

W. D. Shults

The University of Texas—Austin

Oak Ridge National Laboratory

Martin L. Gorbaty

Geoffrey K. Smith

Exxon Research and Engineering C o .

Rohm & Haas C o .

Roland F. Hirsch

Charles S.Tuesday

U.S. Department of Energy

General Motors Research Laboratory

Rudolph J. Marcus

Douglas B. Walters

Consultant, Computers & Chemistry Research

National Institute of Environmental Health

Vincent D. McGinniss

C. Grant Willson

Battelle Columbus Laboratories

I B M Research Department

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.fw001

FOREWORD The ACS S Y M P O S I U M S E R I E S was founded in 1974 to provide a medium for publishing symposia quickly in book form. The format of the Series parallels that of the continuing A D V A N C E S I N C H E M I S T R Y S E R I E S except that, in order to save time, the papers are not typeset but are reproduced as they are submitted by the authors in camera-ready form. Papers are reviewed under the supervision of the Editors with the assistance of the Series Advisory Board and are selected to maintain the integrity of the symposia; however, verbatim reproductions of previously published papers are not accepted. Both reviews and reports of research are acceptable, because symposia may embrace both types of presentation.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.pr001

PREFACE C J R O W I N G W O R L D P O P U L A T I O N S , different degrees of income, religious beliefs, and health concerns have contributed to the increased interest in research on novel sources of protein from seeds, plants, and single-cell organisms. Such research has given rise to changes in consumption patterns and nutritional value of new protein food products. In addition, it has led to concern over the effects of potential antinutrients and large quantities of vegetable protein on health. Research on these subjects has been reported in several books (cf. Chapter 1, Literature Cited), but emphasis was devoted to the major cereals, oilseeds, and legumes (e.g., corn, wheat, barley, soybeans, peanuts, rapeseed). As technology has improved, the literature reporting new achievements in research on vegetable proteins has also grown. Plans for the symposium from which this book was developed were initiated in 1982-83. The aim was to bring together specialists in three primary phases of research on plant proteins and to feature applications in both new and traditional foods, the biological effects of all-vegetable protein diets on human health, and the chemistry of some lesser known plant proteins that are important sources of food in some countries. The speakers and subjects were carefully selected to cover these three areas—the ABCs of plant proteins—and, although it was not possible to include all possible facets of these areas, the organizers sought to provide a good balance on important subjects covered very little or not at all in other symposia and books. The problem of protein malnutrition is very complex and cannot be completely covered in one book, but the chapters of this book provide up-todate balanced coverage of this important subject. This book, I hope, will fill a need for nutritionists, food scientists, and clinicians concerned about nutritional aspects of plant proteins for humans. Views and conclusions expressed herein are those of the authors, whom 1 sincerely thank for their time and effort in presenting their research at the symposium and in preparing their manuscripts for publication in this book. ROBERT L . ORY

U.S. Department of Agriculture New Orleans, LA 70179 December 10, 1985

ix

1 Plant Proteins: The ABCs Robert L. Ory Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, New Orleans, LA 70179

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch001

What has been is what will be and there is nothing new under the sun. [Ecclesiates 1:9] Interest in seed and vegetable proteins has been growing steadily over the past two decades because of the major role plant proteins play in both human and animal diets. Animal proteins are s t i l l acknowledged to have higher nutritional value than those from plant sources but for economic, health, or religious reasons, some populations derive all of their protein from plants. In addition to this interest in new sources of protein, we have also seen a growing concern over antinutrients present in some plant foods and their effect on human health (1-3). Yet none of the plant, seed, or animal proteins we eat today are "new". They have been eaten for centuries - but in different forms. The "new" aspects include more modern ways of food preparation, better technology for measuring chemical composition, nutrients and antinutrients in foods, and a greater awareness of the health implications of food constituents. Proteins are a vital part of living muscle tissue and are one of our most important nutrients. They have been called the building blocks of nutrition because they are broken down by digestive enzymes to provide amino acids for the building and repair of tissues. Animal proteins and those from most legumes and nuts contain all of the essential amino acids but the quantities of some (e.g.: lysine, methionine) in plants are lower. To envision the worldwide consumption of proteins in a different perspective, consider the major sources eaten by humans. Of the average 69 g. protein/day consumed worldwide in 1974, 63% was derived from plants (48% from cereals, roots and tubers, and 15% from fruits, vegetables, nuts, oilseeds and pulses), 36% from animal sources (meats, fish, eggs and dairy products), and 1% from other sources (4). To achieve sufficient essential amino acids or a better amino acid balance (chemical score), plant proteins must be consumed in larger quantities or be blended with other complimentary proteins. This chapter not subject to U.S. copyright. Published 1986, American Chemical Society

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For example, peanut p r o t e i n m e a l , low i n l y s i n e and m e t h i o n i n e , can be blended w i t h such t h i n g s as high methionine c i t r u s seed meal (J>) or r i c e bran f l o u r (6) to improve the chemical s c o r e . Use of l e s s e x p e n s i v e p l a n t p r o t e i n s blended w i t h complementary proteins i s the l o g i c a l and economical way to improve protein n u t r i t i o n f o r those not consuming any animal p r o t e i n , but t h i s has raised questions concerning nutritional quality, presence of antinutrients, and p h y s i o l o g i c a l s i g n i f i c a n c e of such foods on human h e a l t h . Major changes i n l i f e styles i n the past two decades have a l s o had an impact on e a t i n g h a b i t s ; i . e . : more women work out today, life i s l i v e d a t a more r a p i d pace, attitudes about meals prepared at home, meals eaten away from home, and members of f a m i l i e s t h a t e a t t o g e t h e r have changed. These changes have s t i m u l a t e d the i n t r o d u c t i o n of many convenience foods, snack i t e m s , and i n t e r e s t i n n u t r i t i o n a l c o m p o s i t i o n and l a b e l l i n g of processed f o o d s . In addition, consumption of fresh fruits and vegetables, m i l k , m i l k p r o d u c t s , and red meats decreased d u r i n g t h i s p e r i o d w h i l e consumption of snack items and f a s t food s e r v i c e p r o d u c t s increased. Though f a s t food s e r v i c e s are still the largest segment of the f o o d - s e r v i c e i n d u s t r y , w i t h a 3.5% i n c r e a s e i n r e a l growth between 1983 and 1984 ( 7 ) , a growing awareness of n u t r i t i o n by consumers i s showing a s i i g u t t r e n d back to f r e s h foods v e r s u s p r o c e s s e d foods by some g r o u p s . Growth of snacks and convenience foods h a s , n e v e r t h e l e s s , s t i m u l a t e d r e s e a r c h on improving q u a l i t y , f l a v o r , c o l o r , t e x t u r e , n u t r i t i o n a l value and s a f e t y of these new food i t e m s . Research on p l a n t and seed p r o t e i n s has moved f a s t as technology improved and the literature reporting these achievements has a l s o grown. In a d d i t i o n to hundreds of papers p u b l i s h e d i n t e c h n i c a l j o u r n a l s , t h e r e have been s e v e r a l r e c e n t books devoted to seed and p l a n t p r o t e i n s f o r human c o n s u m p t i o n . These were devoted to world p r o t e i n supplies, functional and n u t r i t i o n a l p r o p e r t i e s [8); c h e m i s t r y , b i o c h e m i s t r y and g e n e t i c s of plant proteins (j), 10); or to structure, localization, e v o l u t i o n , b i o s y n t h e s i s , d e g r a d a t i o n , and improvement by b r e e d i n g of seed p r o t e i n s (11). Each of these p r o v i d e s e x c e l l e n t coverage of t h e i r s u b j e c t matter but none focus on a p p l i c a t i o n s of p l a n t p r o t e i n s i n t r a d i t i o n a l and new foods and on b i o l o g i c a l e f f e c t s of p l a n t p r o t e i n s i n the human d i e t . P l a n t foods are b i o l o g i c a l l y more complex than animal food and, as noted earlier, plant p r o t e i n s are n u t r i t i o n a l l y not as complete as animal proteins. P l a n t s c o n s i s t of many d i f f e r e n t t i s s u e s and s t r u c t u r a l elements t h a t i n c l u d e f r u i t s , seeds and seed h u l l s , n u t s , r o o t s and t u b e r s , f l o w e r s , l e a v e s , and stems. Some of these t i s s u e s a r e c o n s i d e r e d u n s u i t a b l e f o r humans because of wide v a r i a t i o n s i n n u t r i t i o n a l value and/or i n a b i l i t y to d i g e s t i n the g a s t r o i n t e s t i n a l t r a c t and they s e r v e as feed f o r a n i m a l s . In c o n t r a s t , animal foods are d e r i v e d p r i m a r i l y from one t i s s u e - m u s c l e ( p l u s e g g s , m i l k and some organ m e a t s ) , but f a r fewer s p e c i e s of a n i m a l s s e r v e as food sources f o r humans than do p l a n t s p e c i e s . The chapters in this book were carefully selected to complement the e x i s t i n g i n f o r m a t i o n on p l a n t p r o t e i n s by f o c u s i n g on the A, B, C ' s : a p p l i c a t i o n s i n new and t r a d i t i o n a l foods, b i o l o g i c a l e f f e c t s of a l l - v e g e t a b l e p r o t e i n d i e t s on humans, and c o m p o s i t i o n and c h e m i s t r y of some l e s s e r - k n o w n sources of p r o t e i n

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ORY

Plant Proteins: The ABCs

3

t h a t c o u l d p l a y an i m p o r t a n t r o l e i n areas where the major seed proteins ( e . g . : s o y , c o t t o n s e e d , peanut, s u n f l o w e r , rapeseed) may not be a v a i l a b l e . D e s p i t e the w e a l t h of i n f o r m a t i o n a v a i l a b l e on the b i o c h e m i s t r y , g e n e t i c s , and n u t r i t i o n a l v a l u e s of p l a n t p r o t e i n s , people eat foods that look, smell, and t a s t e good; not because of nutritional importance. Thus, new blended plant foods or p r o t e i n - s u p p l e m e n t e d snacks or food p r o d u c t s w i l l have to look and t a s t e l i k e the t r a d i t i o n a l items i f they are t o gain s u f f i c i e n t acceptance to become commercially feasible. Absolute food d e f i c i t s are not the s o l e cause of hunger i n the w o r l d s i n c e , theoretically, the 1.088 billion metric tons of food grains produced worldwide c o n t a i n more than enough c a l o r i e s to p r o v i d e the minimal requirement of 2 , 5 0 0 c a l o r i e s / d a y f o r i t s 3 . 5 b i l l i o n people. The b i g problem i s the uneven d i s t r i b u t i o n of these resources. Not j u s t i n poor c o u n t r i e s but even i n small r e g i o n s of the r i c h c o u n t r i e s pockets of m a l n u t r i t i o n s t i l l e x i s t . Some reasons for the poor distribution, besides transportation p r o b l e m s , are the use o f 27-30% of the g r a i n f o r animal feed and almost a f o u r t h of the s u p p l y i s l o s t to insects, rodents, pathogens and w a s t e . S i n c e most snack foods are based on c e r e a l s (wheat, c o r n , r i c e ) , a g r e a t deal of a t t e n t i o n has focused on f o r t i f i c a t i o n / s u p plementation of traditional cereal-based foods. Worldwide, c e r e a l s r e p r e s e n t the major source of c a l o r i e s and p r o t e i n s f o r humans; i . e . : 52% and 47% of the w o r l d ' s average per c a p i t a i n t a k e of c a l o r i e s and p r o t e i n , r e s p e c t i v e l y ( 1 2 ) . Cereal g r a i n s account f o r about 20% of the c a l o r i c i n t a k e ~ T n the U. S. but p r o v i d e 55% i n M e x i c o , 63% i n I n d i a , and 67% i n E a s t A f r i c a . C e r e a l s p r o v i d e 44% of the p r o t e i n requirement i n M e x i c o , 58% i n T h a i l a n d , and 83% i n the M i d d l e E a s t . The p r i n c i p a l c e r e a l of L a t i n America i s maize ( c o r n ) , i n A s i a i t i s r i c e , i n the M i d d l e E a s t i t i s wheat, and i n A f r i c a , o t h e r g r a i n s such as sorghum. Applications and uses of high p r o t e i n legume f l o u r s in f o r t i f i c a t i o n of f r i e d and baked goods and o t h e r food p r o d u c t s f o r both Western and t r a d i t i o n a l d i e t s of d e v e l o p i n g c o u n t r i e s are covered i n g r e a t e r d e t a i l i n Chapters 2 - 6 . To a c h i e v e t h e b a l a n c e needed i n a t r e a t i s e on food p r o t e i n s and to i n c l u d e i n f o r m a t i o n on another growing use of vegetable proteins, t h a t of "meat extenders" i n Western diets, Chapters 7 and 8 d e s c r i b e the a d d i t i o n of p l a n t p r o t e i n s to processed meat p r o d u c t s and whole muscle meats. The incorporation of plant protein (primarily soybean h i g h p r o t e i n meals and i s o l a t e s ) met w i t h l i t t l e success i n the l a t e 1 9 6 0 ' s / e a r l y 1970's because of f l a v o r problems i n defatted f l o u r s or m e a l s . As t e c h n o l o g y i m p r o v e d , off-flavors were removed by p r o d u c t i o n of c o n c e n t r a t e s and i s o l a t e s , so t h a t soy p r o t e i n - e x t e n d e d ground beef p r o d u c t s a r e used e x t e n s i v e l y today i n school lunch programs, i n m i l i t a r y i n s t a l l a t i o n s , and i n s e v e r a l commercial ground beef p r o d u c t s , hamburger, c h i c k e n and tuna h e l p e r s . B i o l o g i c a l e f f e c t s of p l a n t p r o t e i n s on human h e a l t h have a t t r a c t e d wide a t t e n t i o n i n the r e c e n t past because of the p r e sence of various antinutrients such as trypsin inhibitors, h e m a g g l u t i n i n s , and t o x i c p r i n c i p l e s (1). Adequate cooking and/or p r o c e s s i n g i n a c t i v a t e s these m a t e r i a l s and can improve the q u a l i t y

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of p l a n t f o o d s , but the problem of s u f f i c i e n t e s s e n t i a l amino acids i n the p r o t e i n i s not r e s o l v e d s o l e l y by c o o k i n g or processing. B l e n d i n g of two or more p r o t e i n s i s s t i l l n e c e s s a r y t o improve the chemical s c o r e and t h e r e are some b i o l o g i c a l e f f e c t s caused by the p r o t e i n q u a l i t y and q u a n t i t y . The e f f e c t s of p r o t e i n on s k e l e t a l i n t e g r i t y i n e a r l y l i f e and t r a c e m i n e r a l s u t i l i z a t i o n by r a t s and humans are d i s c u s s e d i n Chapters 9 and 10. A d d i t i o n a l c h a p t e r s d e s c r i b i n g the e f f e c t s of p r o t e i n - p r o c y a n i d i n interactions on nutritional quality (Chapter 11), the a c c e p t a b i l i t y of cottonseed protein foods by H a i t i a n children (Chapter 1 2 ) , e f f e c t s of p r o t e i n on experimental atherosclerosis (Chapter 1 3 ) , and on i n t a k e and r e l a t i o n to cancer i n c i d e n c e i n Seventh Day A d v e n t i s t s (Chapter 14) p r o v i d e a d d i t i o n a l information on b i o l o g i c a l e f f e c t s r e l a t e d t o p l a n t p r o t e i n i n t a k e . Chapters 15 and 16 d e s c r i b e t h e e f f e c t s of wet and d r y p r o c e s s i n g on p r o p e r t i e s of legumes f o r food a p p l i c a t i o n s . Because c o m p o s i t i o n and n u t r i t i o n a l p r o p e r t i e s of t h e major food legumes and o i l s e e d s have been r e p o r t e d i n numerous t e c h n i c a l journals and books (listed above), the section devoted to c o m p o s i t i o n and c h e m i s t r y h i g h l i g h t s l e s s e r - k n o w n but p o t e n t i a l l y i m p o r t a n t sources of p l a n t p r o t e i n t h a t have not r e c e i v e d t h e same attention. Some of these food c r o p s have been c u l t i v a t e d f o r many y e a r s so t h a t they a r e not "new" s o u r c e s . Such c r o p s as winged bean, sweet p o t a t o , t r o p i c a l s e e d s , f r u i t s and l e a v e s , yams and c u c u r b i t s are p o t e n t i a l sources of p r o t e i n i n areas where they a r e grown. These are d i s c u s s e d i n g r e a t e r d e t a i l i n the r e m a i n i n g five chapters. The problem of p r o t e i n m a l n u t r i t i o n i s too complex t o be r e s o l v e d w i t h one s i n g l e approach or s i n g l e f o o d . Nontechnical factors such as s u p p l y , availability, distribution, seasonal v a r i a t i o n s , age and h e a l t h s t a t u s o f the consumer a l s o p l a y a role. However, w i t h the t e c h n o l o g i c a l advances made i n the food i n d u s t r y t o d a y , we can now produce food products t h a t are more n u t r i t i o u s and o f t e n cheaper than the t r a d i t i o n a l f o o d s . Cereal grains, the w o r l d ' s p r i n c i p a l source o f food c a l o r i e s , can be f o r t i f i e d o r supplemented w i t h v a r i o u s p l a n t p r o t e i n s to produce very n u t r i t i o u s foods t h a t l o o k , taste, smell, and f e e l like traditional foods. The purpose here i s c e r t a i n l y not to i m p l y t h a t animal p r o d u c t s are bad f o r us but to show t h a t t h e r e are a l s o good p r o t e i n s i n p l a n t s t h a t should not be o v e r l o o k e d i n t h i s search for edible proteins. It seems i r o n i c t h a t man has s u c c e s s f u l l y conquered space by p u t t i n g men on t h e moon and c i r c l i n g the e a r t h i n space s t a t i o n s but s t i l l has not e r a d i c a t e d hunger and m a l n u t r i t i o n on e a r t h .

Literature Cited 1. Ory, R. L. "Antinutrients and Natural Toxicants in Foods". Food and Nutrition Press, Inc., Westport, Conn., 1967. 2. Finley, J. W.; Schwass, D. E. "Xenobiotics in Foods and Feeds". American Chemical Society, Washington, D.C.,1983. 3. Ames, Β. N. Science 1983, 221, 1256. 4. Dunne, C. P. J. Chem. Educ. 1984, 61, 271. 5. Ory, R. L.; Conkerton, E. J.; Sekul, A. A. Peanut Sci. 1978, 5, 31.

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Plant Proteins: The ABCs

Conkerton, Ε J.; Ory, R. L. Peanut Sci. 1983, 10, 56. E l l i s , R. F. Food Process. 1984, 45 (9), 34. Bodwell, C. E.; Petit, L. "Plant Proteins for Human Food". Martinus Nijhoff/Dr. W. Junk Publishers, The Netherlands, 1983. 9. Harborne, J. B.; Van Sumere, C. F. "The Chemistry and Biochemistry of Plant Proteins". Academic Press, Inc., London, 1975. 10. Gottschalk, W.; Muller, H. P. "Seed Proteins: Biochemistry, Genetics, Nutritial Value". Martinus Nihhoff/Dr. W. Junk Publishers, The Netherlands, 1983. 11. Daussant, J.; Mosse J.; Yaughan, J. "Seed Proteins". Academic Press, Inc., London, 1983. 12. Austin, J. E. Cereal Foods World 1978, 23(5), 229. Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch001

6. 7. 8.

RECEIVED

February 10,

1986

5

2 Use of Peanut and Cowpea Flours in Selected Fried and Baked Foods Kay H . McWatters

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch002

Department of Food Science, University of Georgia, College of Agriculture, Experiment Station, Experiment, GA 30212

Successful performance of legume flours as food ingredients depends upon the functional characteristics and sensory qualities they impart to the end product. In snack-type chips, cookies, and doughnuts, sufficient viscoelasticity should be provided to maintain product integrity, allow expansion, and develop surface character. Peanut flour possesses sufficient cohesiveness to form a fried snack-type product if low to moderate temperatures are used in processing the peanuts for flour production. Peanut and cowpea flours can replace at least 30% of the wheat flour in sugar cookies without altering extensively the diameter, height, spread, textural quality, and sensory attributes of the baked product. The quality of cake-type doughnuts containing peanut and cowpea ingredients was improved substantially by using the legumes in the form of flour rather than meal. Akara, deep-fat fried cowpea paste, may be prepared successfully from cowpea meal; conditions employed for pretreating seeds for mechanical decortication, meal particle size, and meal solids to water ratio were important considerations affecting functionality and product quality. S u c c e s s f u l performance of legumes i n foods cooked by f r y i n g o r b a k i n g i n d i c a t e p o s s i b l e a p p l i c a t i o n s f o r t h e i r u s e . Poor p e r f o r m a n c e , on the o t h e r hand, i s u s e f u l i n i n d i c a t i n g a r e a s where c o n d i t i o n s of p r o c e s s i n g o r p r e p a r a t i o n may need t o be m o d i f i e d t o accommodate legume f l o u r usage. T h i s p r e s e n t a t i o n reviews work conducted i n o u r l a b o r a t o r y t o e v a l u a t e t h e performance of peanut and cowpea f l o u r s as i n g r e d i e n t s i n s e v e r a l food p r o d u c t s . Snack-Type Peanut Chips S n a c k - t y p e c h i p s may be prepared by a f a i r l y s i m p l e p r o c e s s from e i t h e r peanut meal o r f l o u r . To prepare f u l l - f a t m e a l , peanuts a r e 0097-6156/86/0312-0008S06.00/0 © 1986 American Chemical Society

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heated a t 93°C f o r 15 min i n a f o r c e d d r a f t o v e n , blanched t o remove t h e t e s t a , c o a r s e l y ground i n a food c h o p p e r , and passed through an 8-mesh s c r e e n t o remove l a r g e p a r t i c l e s . Water i s then added t o form a d o u g h - l i k e m i x t u r e which may be shaped by f o r c i n g the dough through a d i e o r by r o l l i n g and c u t t i n g , f o l l o w e d by d e e p - f a t frying. T h i s p r o d u c t form may be consumed a l o n e o r i n c o m b i n a t i o n with dips or spreads. I n i t i a l work t o e s t a b l i s h c h i p p r e p a r a t i o n c o n d i t i o n s showed t h a t end p r o d u c t c h a r a c t e r i s t i c s were i n f l u e n c e d by meal p a r t i c l e s i z e , by t h e amount of water added t o form t h e dough, and by t h e l e n g t h of time t h e dough was mixed (1). A very acceptable product was a c h i e v e d w i t h t h e s e p r o c e s s c o n d i t i o n s : a blend of p a r t i c l e s i z e s most of which were i n t h e 14-30 mesh r a n g e , an 18% added w a t e r l e v e l , and a m i x i n g time of 5 m i n . The f i n a l p r o d u c t had a c r i s p t e x t u r e , a t y p i c a l r o a s t e d peanut f l a v o r , and was q u i t e s i m i l a r i n composition to f u l l - f a t roasted peanuts. Chips c o n t a i n e d about 49% o i l , 27% p r o t e i n , and 1% m o i s t u r e . Commercial peanut f l o u r s were a l s o e v a l u a t e d f o r t h e i r performance i n p r e p a r a t i o n of peanut c h i p s ( 2 ) . The f o l l o w i n g p r o c e s s i n g t r e a t m e n t s were employed: F l o u r Code A Β C D Ε

P r o c e s s i n g Treatment F u l l - f a t , spray d r i e d P a r t i a l l y d e f a t t e d , unroasted P a r t i a l l y d e f a t t e d , r o a s t e d a t 1 6 0 ° C f o r 15 min P a r t i a l l y d e f a t t e d , r o a s t e d a t 1 7 1 ° C f o r 15 min P a r t i a l l y d e f a t t e d , r o a s t e d a t 1 7 7 ° C f o r 15 min

The p r o c e s s i n g c o n d i t i o n s employed i n p r e p a r a t i o n of t h e f l o u r s i n f l u e n c e d t h e i r appearance and c o l o r , dough-forming and h a n d l i n g c h a r a c t e r i s t i c s , f r y i n g t i m e , and end p r o d u c t q u a l i t y ( F i g u r e 1 ) . F l o u r A ( f u l l - f a t , s p r a y d r i e d ) produced a v e r y o i l y , s t i c k y dough which was d i f f i c u l t t o r o l l , s h a p e , and h a n d l e . These c h i p s r e q u i r e d a 2-min f r y i n g t i m e t o develop a golden brown c o l o r , became d i s t o r t e d i n shape d u r i n g f r y i n g , and were e x t r e m e l y f r a g i l e t o handle a f t e r frying. F l o u r Β ( p a r t i a l l y d e f a t t e d , unroasted) lacked the o i l i n e s s a s s o c i a t e d w i t h f l o u r A but was a l s o d i f f i c u l t t o handle because of i t s s t i c k y nature. Chips prepared from f l o u r Β r e q u i r e d a 7-min f r y i n g time t o become golden brown i n c o l o r and p u f f e d s l i g h t l y during f r y i n g . F l o u r C ( p a r t i a l l y d e f a t t e d , 1 6 0 ° C r o a s t ) produced a dough t h a t was easy t o form and h a n d l e . Chips from f l o u r C r e q u i r e d a 4-min f r y i n g t i m e t o develop a golden brown c o l o r and r e t a i n e d t h e i r shape and s t r u c t u r e d u r i n g f r y i n g . F l o u r D produced a dough t h a t was n e i t h e r s t i c k y nor t a c k y but l a c k e d c o h e s i v e n e s s . Chips prepared from t h i s f l o u r c o m p l e t e l y d i s i n t e g r a t e d d u r i n g the f i r s t few seconds of f r y i n g , i n d i c a t i n g t h a t r o a s t i n g c o n d i t i o n s employed i n f l o u r p r e p a r a t i o n had c o m p l e t e l y d e s t r o y e d t h e f l o u r ' s cohesiveness. No attempts were made t o p r e p a r e c h i p s from f l o u r Ε s i n c e t h e temperature f o r r o a s t i n g t h e nuts was even more severe than t h a t used f o r f l o u r D. Gel e l e c t r o p h o r e t i c p a t t e r n s of w a t e r - s o l u b l e p r o t e i n s i n t h e f i v e peanut f l o u r s were determined as p r e v i o u s l y d e s c r i b e d (2) and show c o n s i d e r a b l e d i f f e r e n c e s i n p r o t e i n c h a r a c t e r ( F i g u r e 2 ) . In

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Figure 1. Peanut f l o u r s and c h i p s prepared from t h e f l o u r s . Reproduced w i t h p e r m i s s i o n from R e f . 2 . C o p y r i g h t 1980, I n s t i t u t e of Food T e c h n o l o g i s t s .

Figure 2. Typical disc polyacrylamide gel e l e c t r o p h o r e t i c p a t t e r n s of w a t e r - s o l u b l e p r o t e i n s from peanut f l o u r s . Reproduced w i t h p e r m i s s i o n from R e f . 2 . C o p y r i g h t 1980, I n s t i t u t e of Food T e c h n o l o g i s t s .

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f l o u r s A and B, t h e components of t h e major g l o b u l i n , a r a c h i n , a r e i n t h e 0 . 5 t o 2 . 0 cm r e g i o n and the n o n a r a c h i n p r o t e i n s appear i n t h e 2 . 0 t o 4 . 0 cm r e g i o n . The p r o c e s s c o n d i t i o n s employed f o r f l o u r C a l t e r e d some of t h e a r a c h i n components ( r e g i o n 1 . 3 t o 2 . 0 cm) and t h e n o n a r a c h i n p r o t e i n s t o forms where they moved as d i f f u s e bands i n the gel p a t t e r n s . The p r o c e s s c o n d i t i o n s used f o r f l o u r s D and Ε denatured v i r t u a l l y a l l of the p r o t e i n s t o s m a l l p o l y p e p t i d e s and/or a g g r e g a t e s ; t h i s was accompanied by a l o s s of b i n d i n g c a p a c i t y and cohesiveness i n chip p r e p a r a t i o n .

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch002

Legume F l o u r Sugar Cookies Sugar c o o k i e s may be prepared by r e p l a c i n g a p o r t i o n of the wheat f l o u r w i t h non-wheat f l o u r s d e r i v e d from p e a n u t , s o y b e a n , and cowpea (3). The legume f l o u r s used i n t h i s study were a d j u s t e d t o a u n i f o r m o i l c o n t e n t of about 1% by s o l v e n t e x t r a c t i o n . Flour p r o t e i n c o n t e n t (wet w e i g h t b a s i s ) was 51% f o r p e a n u t , 46% f o r s o y b e a n , and 21% f o r cowpea. The f l o u r s were used a t 0 , 10, 2 0 , and 30% wheat f l o u r replacement l e v e l s . Peanut and cowpea f l o u r s c o u l d r e p l a c e a t l e a s t 30% of t h e wheat f l o u r w i t h o u t a l t e r i n g e x t e n s i v e l y t h e d i a m e t e r , h e i g h t , s p r e a d , t o p g r a i n , t e x t u r a l g u a l i t y , and s e n s o r y a t t r i b u t e s of the baked p r o d u c t ( F i g u r e 3 ) . T h e r e f o r e , no a l t e r a t i o n s i n f o r m u l a t i o n o r p r e p a r a t i o n procedures would be r e q u i r e d t o accommodate t h e use of peanut o r cowpea f l o u r s i n t h i s t y p e of c o o k i e . Use of soybean f l o u r a t the 20 and 30% l e v e l s , however, decreased c o o k i e d i a m e t e r and spread r a t i o , i n c r e a s e d c o o k i e h e i g h t and h a r d n e s s , and prevented development of a t y p i c a l top g r a i n during b a k i n g . Peanut f l o u r c o o k i e s r e c e i v e d h i g h s e n s o r y scores f o r a l l a t t r i b u t e s . Cowpea f l o u r p r o d u c t s were a l s o h i g h l y a c c e p t a b l e except a t the 30% l e v e l where a beany aroma and f l a v o r were n o t e d . The soy f l o u r c o o k i e s a t the 10% l e v e l were q u i t e a c c e p t a b l e , but t h e poor spread of t h e 20 and 30% soy p r o d u c t s adversely affected texture q u a l i t y . A beany f l a v o r was a l s o apparent a t t h e h i g h e r soy l e v e l s . In subsequent s t u d i e s , soy f l o u r c o o k i e s w i t h good spread c h a r a c t e r i s t i c s were produced by i n c r e a s i n g t h e amount of w a t e r i n the f o r m u l a t o compensate f o r soy f l o u r ' s high water absorption c a p a c i t y . The p r o t e i n c o n t e n t of c o o k i e s was markedly i n f l u e n c e d by the a d d i t i o n and p r o t e i n c o n t e n t of the v a r i o u s legume f l o u r s ( F i g u r e 4 ) . Each increment of peanut f l o u r r a i s e d t h e t o t a l p r o t e i n c o n t e n t i n c o o k i e s by 1.5%. I n c r e a s e s of 1.4% o c c u r r e d w i t h soy f l o u r and 0 . 5 % w i t h cowpea f l o u r . Legume F l o u r Doughnuts The performance of peanut and cowpea f l o u r as i n g r e d i e n t s i n c a k e - t y p e doughnuts has been i n v e s t i g a t e d ( 4 ) . In a d d i t i o n t o s e n s o r y c h a r a c t e r i s t i c s imparted t o t h e end p r o d u c t , t h e i n f l u e n c e of t h e legume f l o u r s on the m a c h i n a b i l i t y of t h e doughnut b a t t e r was found t o be i m p o r t a n t . M a c h i n a b i l i t y i s d e f i n e d as the ease of c u t t i n g , d i s p e n s i n g , and c o n v e y i n g t h e b a t t e r . I n i t i a l tests i n d i c a t e d t h a t peanut and cowpea meals were c o m p a t i b l e i n g r e d i e n t s f o r use i n t h i s t y p e of p r o d u c t , but the f a t c o n t e n t of legume-supplemented doughnuts was c o n s i d e r a b l y h i g h e r than r e f e r e n c e doughnuts made w i t h 100% wheat f l o u r .

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Figure 3. R e p r e s e n t a t i v e sugar c o o k i e s prepared from d e f a t t e d p e a n u t , s o y b e a n , and f i e l d pea f l o u r s a t 0 , 1 0 , 2 0 , and 30% wheat f l o u r replacement l e v e l s . Reproduced w i t h p e r m i s s i o n from Ref. 3 . C o p y r i g h t 1978, American A s s o c i a t i o n of C e r e a l C h e m i s t s .

Figure 4. P r o t e i n c o n t e n t (%) of sugar c o o k i e s prepared from d e f a t t e d p e a n u t , s o y b e a n , and cowpea f l o u r s a t 0 , 1 0 , 2 0 , and 30% wheat f l o u r replacement l e v e l s . Reproduced w i t h p e r m i s s i o n from R e f . 3 . C o p y r i g h t 1978, American A s s o c i a t i o n of C e r e a l Chemists.

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F o l l o w - u p s t u d i e s u t i l i z e d f i n e l y - m i l l e d legume f l o u r s and t h e a d d i t i o n of soybean f l o u r as a f a t - c o n t r o l agent i n an e f f o r t t o improve doughnut q u a l i t y ( 5 ) . The legume p r o d u c t s and doughnuts prepared from them a r e shown i n F i g u r e 5 . On a d r y w e i g h t b a s i s , peanut f l o u r from s o l v e n t e x t r a c t e d peanuts (PF-SE) c o n t a i n e d 0 . 9 % f a t and 54.4% p r o t e i n w h i l e cowpea f l o u r (CF) c o n t a i n e d 1.4% f a t and 25.5% p r o t e i n . Peanut f l o u r from p a r t i a l l y d e f a t t e d untoasted peanuts (PF-PD-U) c o n t a i n e d 34.5% f a t and 34.9% p r o t e i n w h i l e peanut f l o u r from p a r t i a l l y d e f a t t e d peanuts t o a s t e d a t 1 6 0 ° C c o n t a i n e d 34.4% f a t and 37.6% p r o t e i n . Wheat f l o u r r e f e r e n c e (WFR) samples were compared t o doughnuts made w i t h 10% legume f l o u r (LF) o r legume f l o u r p l u s soybean f l o u r (LF + S) added t o i n c r e a s e the t o t a l f l o u r c o n t e n t by 3%. No m a c h i n a b i l i t y problems were encountered except w i t h peanut f l o u r from p a r t i a l l y d e f a t t e d , u n t o a s t e d p e a n u t s . T h i s f l o u r produced a s t i c k y b a t t e r which prevented t h e c u t t i n g / d i s p e n s i n g d e v i c e from c o m p l e t e l y c u t t i n g away t h e doughnut c e n t e r . A l l of t h e legume f l o u r products received very acceptable sensory r a t i n g s . P a n e l i s t s were a b l e t o d e t e c t a " s l i g h t l y beany" aroma i n p r o d u c t s made w i t h t h e p a r t i a l l y d e f a t t e d , u n t o a s t e d peanut f l o u r and a " d e f i n i t e r o a s t e d peanut" aroma i n doughnuts made w i t h p a r t i a l l y d e f a t t e d , t o a s t e d peanut f l o u r . The g r a i n of legume f l o u r - s u p p l e m e n t e d doughnuts was u n i f o r m and f i n e - t e x t u r e d , and the f a t c o n t e n t of t h e t e s t p r o d u c t s was a c c e p t a b l e , c l o s e l y r e s e m b l i n g t h a t of r e f e r e n c e doughnuts. The a d d i t i o n of soy f l o u r p r o v i d e d no added b e n e f i t i n c o n t r o l l i n g t h e amount of f a t absorbed by t h e doughnuts d u r i n g f r y i n g . Akara ( F r i e d Cowpea

Paste)

The U n i v e r s i t y of G e o r g i a i s p a r t i c i p a t i n g i n a c o l l a b o r a t i v e r e s e a r c h p r o j e c t w i t h t h e U n i v e r s i t y of N i g e r i a . The o v e r a l l g o a l of t h e p r o j e c t i s t o i n c r e a s e t h e a v a i l a b i l i t y of cowpeas f o r d e v e l o p i n g c o u n t r y p o p u l a t i o n s by development of t e c h n o l o g i e s t o reduce p o s t h a r v e s t s t o r a g e l o s s e s and t o s i m p l i f y t h e p r e p a r a t i o n of cowpeas. The p r o j e c t i s supported by t h e Bean/Cowpea C o l l a b o r a t i v e Research Support Program (CRSP) and t h e U. S . Agency f o r I n t e r n a t i o n a l Development. Cowpeas a r e an i m p o r t a n t p a r t of t h e d i e t s of West A f r i c a n s . T h e y ' r e grown f o r domestic consumption r a t h e r than f o r e x p o r t and a r e consumed as a b o i l e d v e g e t a b l e and as p a s t e which i s cooked by e i t h e r steaming o r f r y i n g . In o r d e r t o o b t a i n a l i g h t - c o l o r e d p a s t e f r e e of any c o l o r which may be imparted by the seed c o a t o r e y e , peas a r e d e c o r t i c a t e d by manual p r o c e s s e s . The t r a d i t i o n a l wet method c o n s i s t s of s o a k i n g peas i n w a t e r t o l o o s e n t h e seed c o a t , then r u b b i n g t h e seeds t o s e p a r a t e t h e t e s t a from the c o t y l e d o n . The d e c o r t i c a t e d peas a r e then ground i n t o p a s t e e i t h e r i n a m o r t a r , on a s t o n e , o r i n a b l e n d e r i f a v a i l a b l e . The p a s t e i s s t i r r e d o r whipped t o i n c o r p o r a t e a i r , s e a s o n e d , then cooked ( 6 , 7 ) . Chopped peppers and onions a r e t h e most common s e a s o n i n g s , but t o m a t o e s , g i n g e r , o r shrimp a r e a l s o used f o r f l a v o r . The f r i e d p r o d u c t ( F i g u r e 6 ) , c a l l e d a k a r a i n N i g e r i a , i s consumed as a snack food and b r e a k f a s t food and has a b r e a d - l i k e c h a r a c t e r s i m i l a r t o hush p u p p i e s . In a d d i t i o n t o home p r e p a r a t i o n , a k a r a i s prepared and s o l d by s t r e e t vendors i n t h e

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F i g u r e 5 . R e p r e s e n t a t i v e doughnuts prepared from peanut f l o u r - s o l v e n t e x t r a c t e d ( P F - S E ) , peanut f l o u r - p a r t i a l l y d e f a t t e d u n t o a s t e d ( P F - P D - U ) , peanut f l o u r - p a r t i a l l y d e f a t t e d - t o a s t e d ( P F - P D - T ) , and cowpea f l o u r ( C F ) . WFR = wheat f l o u r r e f e r e n c e , LF = 10% legume f l o u r (peanut o r cowpea), LF + S = 10% legume f l o u r (peanut o r cowpea) + 3% soybean f l o u r . Reproduced w i t h p e r m i s s i o n from R e f . 5 . C o p y r i g h t 1982, The American Peanut Research and E d u c a t i o n S o c i e t y .

F i g u r e 6 . R e p r e s e n t a t i v e b a t c h of a k a r a , a b r e a d - l i k e p r o d u c t made by d e e p - f a t f r y i n g cowpea p a s t e . Reproduced w i t h p e r m i s s i o n from R e f . 6 . C o p y r i g h t 1980, I n s t i t u t e of Food Technologists.

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Peanut and Cowpea Flours

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m a r k e t p l a c e and by s m a l l - s c a l e p r o c e s s o r s f o r home d e l i v e r y and catering services. A major f o c u s of the p r o j e c t has been development of a p r o c e s s t o make cowpea meal o r f l o u r t h a t c o u l d be implemented a t the village level. The meal would be a r e a d y - t o - u s e convenience p r o d u c t t o which t h e consumer c o u l d s i m p l y add water and then proceed t o the f i n a l s t e p s of p r e p a r a t i o n . The time-consuming and l a b o r - i n t e n s i v e s t e p s of s o a k i n g , d e c o r t i c a t i n g , and g r i n d i n g would be e l i m i n a t e d . If a convenience p r o d u c t such as cowpea meal i s t o f i n d f a v o r w i t h t h e consumer, i t must produce an end p r o d u c t which i s s i m i l a r i n q u a l i t y t o t h a t produced by t h e t r a d i t i o n a l p r o c e s s . E s s e n t i a l t o a t t a i n m e n t of a l i g h t , spongy t e x t u r e i n t h e f r i e d p r o d u c t i s t h e f o r m a t i o n , d u r i n g t h e whipping of cowpea p a s t e , of a foam w i t h a p p r o p r i a t e volume and c o n s i s t e n c y . Commercial cowpea f l o u r a v a i l a b l e i n N i g e r i a has not been w e l l r e c e i v e d by consumers because of i t s poor water a b s o r p t i o n and because a k a r a prepared from t h e f l o u r i s heavy, l a c k s c r i s p n e s s , and l a c k s t h e f l a v o r t y p i c a l of p r o d u c t s made from f r e s h p a s t e ( 8 ) . A major d i f f e r e n c e found between t r a d i t i o n a l p a s t e and commercial f l o u r o b t a i n e d i n N i g e r i a was p a r t i c l e s i z e d i s t r i b u t i o n ( 9 ) . The f l o u r was more f i n e l y m i l l e d than t r a d i t i o n a l p a s t e w i t h 47% of t h e f l o u r p a r t i c l e s r i d i n g a 400-mesh s c r e e n compared t o 16% a t t h e 400-mesh s i z e f o r t h e p a s t e ( F i g u r e 7 ) . The g r e a t e s t c o n c e n t r a t i o n of p a s t e p a r t i c l e s (64%) was i n the 50-100 mesh range whereas most of t h e f l o u r p a r t i c l e s (68%) were c o n c e n t r a t e d i n t h e 200-400 mesh range. Attempts t o make a k a r a from t h e f l o u r , u s i n g i n s t r u c t i o n s s u p p l i e d by t h e m a n u f a c t u r e r , were u n s u c c e s s f u l because the b a t t e r was t o o l i q u i d t o d i s p e n s e and f r y p r o p e r l y . Even a f t e r r e d u c i n g the amount of w a t e r i n t h e b a t t e r , cooked p r o d u c t s were u n a t t r a c t i v e and u n d e s i r a b l y d r y , d e n s e , and t o u g h . These f i n d i n g s prompted f u r t h e r study on t h e e f f e c t s of p a r t i c l e s i z e on cowpea p a s t e c h a r a c t e r i s t i c s and a k a r a - m a k i n g q u a l i t y . Three s c r e e n s i z e s ( 2 . 0 , 1 . 0 , 0 . 5 mm) were used f o r m i l l i n g cowpeas and produced the p a r t i c l e s i z e d i s t r i b u t i o n s shown i n F i g u r e 8. With t h e 2 . 0 mm s c r e e n , p a r t i c l e s were c o n c e n t r a t e d (76%) i n the 30-100 mesh r a n g e . With the 1 . 0 mm s c r e e n , most of t h e p a r t i c l e s (82%) were i n t h e 50-200 mesh r a n g e . E i g h t y per c e n t of t h e p a r t i c l e s were i n t h e 200-400 mesh range w i t h t h e 0 . 5 mm s c r e e n . In p r e p a r i n g a k a r a from each m i l l e d p r o d u c t , t o o many l a r g e p a r t i c l e s s t i l l remained i n the 2 mm m a t e r i a l t o make a smooth p a s t e . However, h i g h l y a c c e p t a b l e a k a r a w i t h u n i f o r m shape was produced from t h i s m a t e r i a l a f t e r the p a s t e was ground t o e l i m i n a t e t h e l a r g e particles. With t h e 0 . 5 mm s c r e e n , t h e p a s t e was v e r y f l u i d and e x t r e m e l y d i f f i c u l t t o d i s p e n s e , b e h a v i o r which c l o s e l y resembled t h a t e x h i b i t e d by the commercial cowpea f l o u r . Akara prepared from t h e 0 . 5 mm m a t e r i a l was a l s o e x t r e m e l y d i s t o r t e d . Of t h e t h r e e s c r e e n s i z e s compared, the 1 . 0 mm s c r e e n produced t h e most d e s i r a b l e p a r t i c l e s i z e d i s t r i b u t i o n ; a l t h o u g h t h e p a s t e produced from t h e 1 . 0 mm m a t e r i a l was somewhat more f l u i d than d e s i r e d , i t appeared t h a t adjustments c o u l d be made i n h y d r a t i o n of t h e meal t o a c h i e v e an appropriate batter v i s c o s i t y . The poor performance of f i n e l y m i l l e d cowpea f l o u r s may be due t o changes i n p h y s i c a l form and s t r u c t u r e which o c c u r as a r e s u l t of milling. Sefa-Dedah and S t a n l e y (10) i n v e s t i g a t e d t h e r e l a t i o n s h i p of m i c r o s t r u c t u r e of cowpeas t o water a b s o r p t i o n and d e c o r t i c a t i o n

PLANT PROTEINS

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch002

50-

8

14

30

50

Tyler Screen S i z e

100

200

400

Pan

(mesh)

F i g u r e 7. P a r t i c l e s i z e d i s t r i b u t i o n of t r a d i t i o n a l l y p r o c e s s e d cowpea p a s t e and m e c h a n i c a l l y m i l l e d cowpea f l o u r . Reproduced w i t h p e r m i s s i o n from Ref. 9 . C o p y r i g h t 1983, American A s s o c i a t i o n of C e r e a l C h e m i s t s .

Tyler Screen S i z e

(mesh)

Figure 8. E f f e c t of m i l l s c r e e n s i z e on p a r t i c l e s i z e d i s t r i b u t i o n of cowpea m e a l / f l o u r . Reproduced w i t h p e r m i s s i o n from Ref. 9 . C o p y r i g h t 1983, American A s s o c i a t i o n of C e r e a l Chemists.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch002

2.

MCWATTERS

Peanut and Cowpea Flours

17

p r o p e r t i e s and found t h a t w a t e r uptake of whole seeds was a s e q u e n t i a l p r o c e s s r e l a t e d t o t h e s e e d ' s c e l l u l a r s t r u c t u r e . When t h e form of t h e seed becomes so a l t e r e d by a p r o c e s s such as m i l l i n g t h a t s t r u c t u r a l and c o m p o s i t i o n a l components a r e v a s t l y d i f f e r e n t from t h o s e of t h e i n t a c t s e e d , then the c o n d i t i o n s which a l l o w f o r t h e s e q u e n t i a l uptake of w a t e r no l o n g e r e x i s t . In subsequent s t u d i e s t o determine t h e most a p p r o p r i a t e w a t e r l e v e l f o r h y d r a t i n g cowpea meal produced from t h e 1 . 0 mm s c r e e n , s u f f i c i e n t w a t e r was added t o t h e meal t o a d j u s t the m o i s t u r e c o n t e n t t o 5 6 , 5 8 , o r 60% (H). P r e l i m i n a r y s t u d i e s had shown t h a t a 54% w a t e r l e v e l produced a b a t t e r t h a t was t o o t h i c k f o r w h i p p i n g , d i s p e n s i n g , and f r y i n g , and a 62% w a t e r l e v e l was t o o t h i n . T r a d i t i o n a l p a s t e made from soaked peas c o n t a i n s about 61% w a t e r and has a v i s c o s i t y v a l u e a f t e r w h i p p i n g of about 302 p o i s e . By c o m p a r i s o n , t h e v i s c o s i t y of p a s t e made from h y d r a t e d cowpea meal was 578 p o i s e a t t h e 56% w a t e r l e v e l , 441 p o i s e a t t h e 58% w a t e r l e v e l , and 333 p o i s e a t t h e 60% l e v e l . The 60% w a t e r l e v e l produced p a s t e w i t h f l o w p r o p e r t i e s and a cooked p r o d u c t w i t h p h y s i c a l c h a r a c t e r i s t i c s more l i k e t h e t r a d i t i o n a l p r o d u c t than t h e o t h e r water l e v e l s . Sensory a t t r i b u t e s of a k a r a made from t h e 1 mm s c r e e n f l o u r hydrated t o a 60% m o i s t u r e c o n t e n t b e f o r e c o o k i n g were a c c e p t a b l e when compared t o t r a d i t i o n a l a k a r a (H). A major d i f f e r e n c e i n a k a r a prepared from hydrated meal and t h a t prepared from t r a d i t i o n a l p a s t e i s i n t h e f a t c o n t e n t of t h e cooked p r o d u c t . On a d r y w e i g h t b a s i s , t r a d i t i o n a l a k a r a c o n t a i n s about 38% f a t whereas a k a r a made from meal h y d r a t e d t o a 60% m o i s t u r e c o n t e n t c o n t a i n s 29% f a t . A f r e q u e n t comment made by s e n s o r y p a n e l i s t s i s t h a t a k a r a made from meal has a d r i e r t e x t u r e and mouthfeel than t r a d i t i o n a l a k a r a . S i n c e t h e m o i s t u r e c o n t e n t of t r a d i t i o n a l and meal-based a k a r a i s s i m i l a r (about 4 5 % ) , t h e p e r c e i v e d d r i e r t e x t u r e of t h e meal p r o d u c t s i s p r o b a b l y due t o t h e i r lower f a t c o n t e n t . A l t h o u g h a f r i e d cowpea p a s t e p r o d u c t such as a k a r a i s u n f a m i l i a r t o consumers i n t h e Western w o r l d , t h i s use f o r cowpeas may have a p p l i c a t i o n as a snack food o r as a b r e a d - l i k e accompaniment f o r f i s h o r p o u l t r y . Legumes a l r e a d y p l a y an i m p o r t a n t r o l e i n t h e d i e t s of t h e w o r l d ' s p o p u l a t i o n . Applications i n which legumes p e r f o r m s u c c e s s f u l l y i n c r e a s e t h e p o t e n t i a l f o r e x t e n d i n g t h e i r usage even f u r t h e r . Acknowledgments Supported by S t a t e and Hatch funds a l l o c a t e d t o t h e Georgia A g r i c u l t u r a l Experiment S t a t i o n s , by a g r a n t from t h e Bean/Cowpea C o l l a b o r a t i v e Research Support Program (U. S . Agency f o r I n t e r n a t i o n a l Development), and by funds from t h e Georgia A g r i c u l t u r a l Commodity Commission f o r P e a n u t s .

Literature Cited 1. 2. 3. 4.

McWatters, Experiment McWatters, McWatters, McWatters,

K.; Heaton, Ε. K. Univ. Georgia Coll. Agric. Stations Research Bulletin 106, 1972; pp. 1-17. Κ. H.; Cherry, J . P. J. Food Sci. 1980, 45, 831. Κ. H. Cereal Chem. 1978, 55, 853. Κ. H. Peanut Sci. 1982, 9, 46.

18

P L A N T PROTEINS

5. 6. 7. 8. 9. 10. 11.

McWatters, Κ. H. Peanut Sci. 1982, 9, 101. McWatters, Κ. H.; Flora, F. Food Technol. 1980, 34 (11), 71. McWatters, Κ. H.; Brantley, Β. B. Food Technol. 1982, 36 (1), 66. Dovlo, F. E . ; Williams, C. E . ; Zoaka, L. International Develop. Research Center Public. IDRC-055e, 1976; pp. 1-96. McWatters, Κ. H. Cereal Chem. 1983, 60, 333. Sefa-Dedah, S.; Stanley, D. W. Cereal Chem. 1979, 56, 379. McWatters, K. H.; Chhinnan, M. S. J . Food Sci. 1985, 50, 444.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch002

RECEIVED December 13, 1985

3 Use of Field-Pea Flours as Protein Supplements in Foods 1

Barbara P. Klein and Martha A. Raidl

Department of Foods and Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch003

Legume seeds, such as soy and other pulses, are widely used as protein sources in the human diet. Recent advances in technology suggest that protein concentrates and isolates made by relatively simple methods can be incorporated into food products. Flours made from field peas by wet or dry milling, or air classification, possess distinctive sensory, functional and nutritional characteristics. Compositional differences in the pea seeds influence the quality of the end products. Pea flours have been used for protein enrichment of a number of cereal-based products; however, undesirable sensory characteristics may limit their use, in spite of improved functional effects in food systems. The production of volatile compounds during cooking and baking of foods with pea supplementation affects their acceptability. Enzyme systems active in unheated pea flours may contribute to their functional properties, but adversely affect the sensory quality of the food. Legume seeds, such as soybeans (Glycine max L . ) , faba beans ( V i c i a faba L.), cow peas (Vigna unquiculata L . ) , navy beans (Phaseolus v u l g a r i s L.) and f i e l d peas (Pisum sativum L . ) , are widely used as protein sources i n the human d i e t . In many parts o f the world, legumes are a major contributor to both c a l o r i c and protein intakes. The advantages o f using beans are many: they have long storage l i v e s , even under adverse environmental conditions; they are e a s i l y transported; and they require minimum equipment for preparation. Soybeans have received more attention than any o f the other legumes or pulses. Their high protein and o i l content make them a valuable commodity, both from an economic and n u t r i t i o n a l standpoint. The major uses o f soybeans have been i n processed 1

Current address: Coca-Cola Foods, P.O. Box 550, Plymouth, F L 32768.

0097-6156/86/0312-0019$06.00/0 © 1986 American Chemical Society

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch003

20

PLANT PROTEINS

products, e i t h e r as o i l or as high protein f l o u r s and concentrates. The f u n c t i o n a l i t y of soy products d i f f e r s widely depending on the time, temperature and moisture conditions used i n processing (1). Legumes other than soy are more often consumed as the whole bean, e i t h e r cooked or ground i n t o a f l o u r . Consumption of legumes i s higher i n less developed countries than i n the more i n d u s t r i a l i z e d . In India, f o r example, consumption of legumes and pulses exceeds 60 grams per c a p i t a per day (2) while i n the United States and the United Kingdom, i t i s only about 10 to 15 grams per capita per day (3). F i e l d peas, both yellow and green, are grown i n Canada, the Northwest United States, and to a lesser extent, i n Northern Europe. In the United States, the primary i n t e r e s t i n peas has been i n the fresh, immature, green vegetable, which i s canned or frozen, rather than i n the mature dry seed. Thus, much of the genetic research has been directed towards improving appearance, y i e l d , disease resistance, canning and freezing q u a l i t y , instead of attempting to increase protein content or q u a l i t y . In the past ten years, advances i n processing technology have made i t possible to produce pea protein concentrates by some of the same methods used for soy proteins, and more importantly, by r e l a t i v e l y simple methods such as a i r c l a s s i f i c a t i o n . V a r i a b i l i t y i n Composition of F i e l d Peas The composition of the f i e l d pea depends not only on the species, but also on the c u l t i v a r that i s being processed (4,5). Variations e x i s t among c u l t i v a r s (e.g., Trapper, Century) i n p r o t e i n , f a t , carbohydrate (crude f i b e r and s t a r c h ) , and ash contents, as shown i n Table I. Tyler and Panchuk (6) noted that the composition of f i e l d peas at d i f f e r e n t stages of maturity also affected the composition of the products, and t h i s could u l t i m a t e l y influence t h e i r f u n c t i o n a l i t y i n foods. Table I.

Proximate Composition of Peas (g/100 g) Protein

Fat

Total Carbohydrate

Ash

24.1

1.3

60.3

2.6

Trapper cv. (8)

14.5 18.3 24.2 28.5

4.1 3.7 3.3 3.0

Century cv. (4)

23.3

1.2

Dry seeds

(J)

Starch 59.8 56.7 53.8 49.7 54

Fiber 4.3 3.7 3.5 3.1

3.3 3.0 2.7 2.8

7.6

2.5

Protein Components of F i e l d Pea Flour The reported protein content of f i e l d peas ranges from 13.3 to 39.7%

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch003

3.

KLEIN A N D RAIDL

21

Field-Pea Flours as Protein Supplements

and i s influenced by genetic and environmental factors (8-13). Analysis of 1452 v a r i e t i e s of f i e l d peas (Pisum sativum) showed that the protein varied from 15.5 to 39.7% (10), and even g e n e t i c a l l y i d e n t i c a l pea plants grown the same year on the same f i e l d produced seeds whose protein content ranged from 19.3 to 25.2% (11). More than 75% of a l l f i e l d peas grown are of the Trapper variety and t h e i r protein content can range from 13.3 to 27.1% (8). Watt and M e r r i l l (7) i n d i c a t e that the protein content of mature dry peas i s 24.1%, but Reichert and Mackenzie (8) found that only 14% of t h e i r 198 f i e l d pea samples had protein l e v e l s greater than or equal to t h i s value (see Table I ) . Environmental factors which a f f e c t protein content of f i e l d peas include nitrogen f e r t i l i z e r (14), maturation (15), s o i l Ρ and Κ content (16), and temperature (17). The protein corrEent of f i e l d peas i s important since i t ultimately a f f e c t s the amount of protein i n f i e l d pea concentrates or i s o l a t e s (18). Protein content of dehulled Trapper f i e l d peas i s negatively correlated with the amino acids threonine, c y s t i n e , g l y c i n e , alanine, methionine, and l y s i n e and p o s i t i v e l y correlated with glutamic acid and arginine (8). Holt and Sosulski (19) obtained s i m i l a r c o r r e l a t i o n s with Century f i e l d peas for a l l amino acids except glutamic a c i d . Other investigators (20) also found that s u l f u r amino acids (cys, met) are negatively correlated with protein content. The main storage proteins i n f i e l d peas are two globulins (Table I I ) , v i c i l i n and legumin, which are s i m i l a r to the 7S and U S Table I I . Proteins i n Peas and Soybeans (g/100 g) Albumins

3

Globulins*

3

(21) Glutelin

Peas

21

66

12

Soy

10

90

0

^Soluble i n water. Soluble i n salt solution. S o l u b l e i n d i l u t e acid or base. b

c

f r a c t i o n of soy protein (12). However, legumin appears to have a more compact structure than the U S soybean f r a c t i o n , and v i c i l i n , although comparable to the 7S f r a c t i o n , i s thought to be two proteins. V i c i l i n has a molecular weight of 186,000; legumin i s approximately 331,000. These proteins do not p a r t i c i p a t e to the same degree as soy proteins i n a s s o c i a t i o n - d i s s o c i a t i o n reactions when there i s a change i n i o n i c strength (21). The two pea globulins d i f f e r i n t h e i r properties: for example, v i c i l i n i s soluble at pH 4.7, legumin i s not; legumin i s not heat-coagulable, but v i c i l i n i s . The globulins i n peas appear s i m i l a r to those i n other legumes as well as i n soybeans.

0

22

P L A N T PROTEINS

The protein e f f i c i e n c y r a t i o (PER) of f i e l d pea f l o u r s i s considerably l e s s than that of casein (1.46 vs. 2.50), and somewhat less than that of soy f l o u r (1.81). However, composites of wheat f l o u r and pea or r i c e and pea (50% of the protein from each source) had PER s of 2 or more (22). Thus, supplementation of cereals with pea f l o u r r e s u l t s i n improvement of protein q u a l i t y . 1

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch003

Starch Components of F i e l d Pea Flour Starch content of f i e l d peas (Pisum sativum L., cv. Trapper) ranges from 43.7 to 48% and, a f t e r being subjected to pin m i l l i n g and a i r c l a s s i f i c a t i o n , produces a f l o u r containing 78% starch (9,12,13). The predominant polysaccharide i n dehulled f i e l d pea f l o u r i s starch (49.7-59.8%) and the major soluble sugars are a-galactosides (4.78%) and sucrose (1.85-2.2%) (8,23,24). Verbascose i s the major α-galactoside present i n f i e l d pea f l o u r (23,24). The a-galactosides are the main contributors to the flatulence caused by ingestion of legume f l o u r s . Pea starch granules are o v a l , sometimes f i s s u r e d , with a diameter of 20-40 ym (13). Molecular and s t r u c t u r a l c h a r a c t e r i s t i c s of the two main components of f i e l d pea starch—amylose and amylopectin—are important i n determining functional properties (25,26). Smooth f i e l d pea starch concentrate contains 97.2% starch of which 30.3-37.8% i s amylose (9,23,25-27), and wrinkled pea starch concentrate contains 94.8% starch, which i s 64% amylose (26). The g e l a t i n i z a t i o n temperature of smooth pea starch i s between 64 to 69 C., and that of wrinkled pea starch i s greater than 99 C to 115 C. G e l a t i n i z a t i o n temperature depends on maturity of f i e l d pea seed and amylose content (26,27). Processing Methods for Pea

Flours

The f i e l d pea seed i s f i r s t cleaned, usually dehulled, and ground to a f l o u r p r i o r to being separated i n t o starch and protein f r a c t i o n s (4). The f l o u r i s pale yellow or green, depending on the c u l t i v a r . The separation of f i e l d pea f l o u r i n t o protein and starch concentrates i s achieved using e i t h e r a wet or dry m i l l i n g process. The wet processing of f i e l d peas produces a r e l a t i v e l y pure protein concentrate or i s o l a t e composed of approximately 60% protein and a starch f r a c t i o n containing about 2% protein (22). Unfortunately t h i s process requires evaporation of large amounts of water, making i t expensive and technologically complex (4). Dry processing of f i e l d peas uses pin m i l l i n g and a i r c l a s s i f i c a t i o n techniques (4,23). Whole or dehulled f i e l d pea seeds are pin m i l l e d to y i e l d f l o u r s with a s p e c i f i c p a r t i c l e s i z e which can be further separated i n t o protein and starch f r a c t i o n s using an a i r c l a s s i f i e r (9). In t h i s system, using an Alpine A i r C l a s s i f i e r for example, a s p i r a l flow of a i r i s used to separate the jagged and " l i g h t " protein p a r t i c l e s from the smooth, round and "heavy" starch granules, r e s p e c t i v e l y , i n t o f i n e and coarse f r a c t i o n s (4,18). The starch f r a c t i o n i s then washed, centrifuged, and defibered to y i e l d a pure starch concentrate (9). Many investigators have found a i r c l a s s i f i c a t i o n e f f e c t i v e i n separating starch and p r o t e i n - r i c h fractions i n other starchy grain legumes as well as i n f i e l d peas (4,18,23,28-30).

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch003

3.

KLEIN A N D RAIDL

Field-Pea Flours as Protein Supplements

23

The composition of protein and starch f r a c t i o n s produced from pin m i l l i n g and a i r c l a s s i f i c a t i o n are related to a number o f v a r i a b l e s : v a r i a b i l i t y i n composition of f i e l d pea c u l t i v a r s , number of passes through pin m i l l and a i r c l a s s i f i e r , vane settings and protein content of peas, and seed moisture (5,9,23,31). Protein content of f i e l d peas i s negatively correlated with l i p i d , c e l l wall material (CWM), sugar, and ash content and p o s i t i v e l y correlated with starch separation e f f i c i e n c y and protein separation e f f i c i e n c y i n a i r c l a s s i f i c a t i o n of pea f l o u r . The lower separation e f f i c i e n c y of low protein peas may be due to t h e i r high l i p i d and CWM content which makes d i s i n t e g r a t i o n of seeds and separation i n t o protein and starch p a r t i c l e s by pin m i l l i n g d i f f i c u l t . I t i s suggested that peas with a s p e c i f i c protein content should be used i n order to c o n t r o l the protein and starch f r a c t i o n contents (18). As seed moisture i n f i e l d peas decreases, there i s a decrease i n starch f r a c t i o n y i e l d , protein content of starch f r a c t i o n , protein content of protein f r a c t i o n , and percent starch separation e f f i c i e n c y , and a concurrent increase i n protein f r a c t i o n y i e l d , percent starch i n starch f r a c t i o n , percent starch i n protein f r a c t i o n , percent protein separation e f f i c i e n c y , and percent neutral detergent f i b e r i n the protein f r a c t i o n . Lower moisture content o f f i e l d peas improves m i l l i n g e f f i c i e n c y and r e s u l t s i n more complete separation of protein and starch f r a c t i o n s , which could explain the increase i n protein f r a c t i o n y i e l d and percent starch i n starch f r a c t i o n , improved protein separation e f f i c i e n c y and l e s s protein i n the starch f r a c t i o n . The decrease i n starch separation e f f i c i e n c y was probably due to the increased starch content of protein f r a c t i o n and increased protein f r a c t i o n y i e l d with lower seed moisture. Finer grinding of CWM may explain the increase i n NDF i n protein fractions (32). Pea Protein Concentrates and Isolates I s o e l e c t r i c p r e c i p i t a t i o n and u l t r a f i l t r a t i o n procedures have been used to produce protein i s o l a t e s from f i e l d peas (13). Sumner et a l . (33) used an a l k a l i n e extraction method to produce pea protein i s o l a t e e i t h e r as sodium proteinate or as an i s o e l e c t r i c product which was then dried using e i t h e r a spray, drum, or freeze drying method. The i s o e l e c t r i c process and u l t r a f i l t r a t i o n process produced f i e l d pea protein i s o l a t e s which contained 91.9% and 89.5% p r o t e i n , respectively (13). The spray, freeze, and drum drying processes produced sodium proteinate i s o l a t e s which contained 85.8, 83.0, and 83.2% p r o t e i n , r e s p e c t i v e l y , while t h e i r i s o e l e c t r i c counterparts contained 88.5, 90.0, and 85.9% protein (33). The r e s u l t i n g pea protein i s o l a t e i s a cream to beige color and tastes f a i r l y bland (13). The color depends on the method used to dry the i s o l a t e s . Spray-dried i s o l a t e s are the l i g h t e s t , while freeze-dried and drum-dried are the darkest. Oxidation of polyphenols causes the darkening of freeze-dried products while the M a i l l a r d reaction from heat processing creates a darker product i n drum-dried i s o l a t e s (33). Carbohydrate Content.

Protein fractions were found to contain AO to

24

PLANT PROTEINS

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch003

90% higher l e v e l s of α-galactosides when compared to the corresponding f i e l d pea f l o u r s . Thus, the protein f r a c t i o n contained high l e v e l s of verbascose and stachyose and the major galactosides remained with the protein f r a c t i o n during a i r c l a s s i f i c a t i o n (24). Amino Acid Content. Amino acid content of f i e l d pea products i s related to protein l e v e l , method of processing, and f r a c t i o n (starch or p r o t e i n ) . The protein f r a c t i o n contains fewer a c i d i c ( g l u , asp) amino acids than the starch f r a c t i o n and more basic ( l y s , h i s , arg) amino acids than the starch f r a c t i o n . Also, there are more aromatic ( t y r , phe) amino a c i d s , l e u , i s o , ser, v a l , and pro i n the protein f r a c t i o n than i n the starch f r a c t i o n (5). An amino a c i d p r o f i l e of pea protein concentrate shows r e l a t i v e l y high l y s i n e content (7.77 g aa/16 g Ν) but low s u l f u r amino acids (methionine and cystine) (1.08-2.A g aa/16 g Ν). Therefore, i t i s recommended that a i r c l a s s i f i c a t i o n or u l t r a f i l t r a t i o n be used because acid p r e c i p i t a t i o n r e s u l t s i n a whey f r a c t i o n which contains high l e v e l s of s u l f u r amino acids (12,23). Also, drum drying sodium proteinates decreases l y s i n e content due to the M a i l l a r d reaction (33). Nitrogen S o l u b i l i t y Index. Nitrogen s o l u b i l i t y index (NSI) indicates the extent of denaturation of a protein and correlates well with the functional c h a r a c t e r i s t i c s of protein ingredients. NSI values are influenced by a number of f a c t o r s , such as pH, temperature, p a r t i c l e s i z e of product, process used for protein i s o l a t i o n , and protein content (34). Pea protein i s o l a t e produced at pH 3 and 7 using u l t r a f i l t r a t i o n exhibited 81% nitrogen s o l u b i l i t y and only 66% s o l u b i l i t y when the i s o e l e c t r i c p r e c i p i t a t i o n method was used (13). Sodium proteinate i s o l a t e s subjected to freeze, spray or drum drying processes had lower nitrogen s o l u b i l i t y than the corresponding i s o e l e c t r i c protein i s o l a t e s (33). The percent nitrogen s o l u b i l i t y of the i s o l a t e s varied from 0 to 100% over a pH range of 3-10. The lowest nitrogen s o l u b i l i t y values occurred at pH 4.5 (the i s o e l e c t r i c point) for a l l products. The low NSI values for drum dried sodium proteinate over t h i s pH range were probably due to protein denaturation during processing. Higher NSI values occurred i n the r e l a t i v e l y undenatured spray- and freeze-dried pea protein i s o l a t e s (33). Nitrogen s o l u b i l i t y index i s i n v e r s e l y related to protein l e v e l , i . e . , as the protein l e v e l increases, NSI decreases (8). Another factor r e l a t e d to s o l u b i l i t y of seed nitrogen i n a f l o u r and d i s t i l l e d water suspension i s the concentration of water-soluble n a t u r a l l y occurring s a l t s , since s a l t - s o l u b l e globulins are the major proteins found i n peas (21). Also, differences i n pea mineral content may play a r o l e i n NSI. Water Absorption. Water absorption of pea protein i s o l a t e s depends on pH and processing method used to produce the i s o l a t e . I s o e l e c t r i c pea protein i s o l a t e absorbed 2.7 to 2.8 times i t s weight of water at pH 7 while UF pea protein i s o l a t e absorbed 3.3 times i t s weight of water at pH 2.5 and twice i t s weight i n water at pH 8.5 (13). These low water absorption values may be due to the high nitrogen s o l u b i l i t i e s of these proteins (35).

3.

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Field-Pea Flours as Protein Supplements

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch003

Use of F i e l d Pea Products i n Cereal-Based

25

Products

Although there are some references to the incorporation of pea f l o u r s or concentrates i n meat systems (12,22^6), the primary use of f i e l d pea f l o u r s or concentrates has been i n baked products or pastas. Most of the studies conducted on baked products have been with pea f l o u r that has had l i t t l e or no heat treatment. Thus, the f l o u r can be considered enzyme-active. As a storage organ for the plant, the i n t a c t pea seed contains a complex assortment of enzymes, including amylases, proteases, lipases and lipoxygenases, as well as a variety of o x i d a t i v e enzymes necessary for seed metabolism and germination. The function of the enzymes from the physiological standpoint i n the plant i s very d i f f e r e n t from t h e i r e f f e c t s i n a food system. Peas contain very low l e v e l s of a n t i - n u t r i t i o n a l f a c t o r s , namely t r y p s i n i n h i b i t o r and hemagglutinins, when compared with soy (37). Thus, heating of pea flours i s not e s s e n t i a l to inactivate these compounds. F i e l d Pea Flours i n Pasta. Incorporation of non-wheat f l o u r s into noodles improves the protein content and q u a l i t y , but may have an adverse e f f e c t on the f l a v o r and texture of the pasta. Hannigan (38) reported that 10% s u b s t i t u t i o n of wheat f l o u r with pea or soy f l o u r resulted i n s a t i s f a c t o r y q u a l i t y of Japanese Udon noodles. When the pea f l o u r was heated, the flavor was considerably improved. Cooked yellow pea f l o u r - f o r t i f i e d noodles were comparable to the control with respect to sensory c h a r a c t e r i s t i c s and y i e l d . Nielsen et a l . (39) used pea flour and pea protein concentrate, both cooked and raw, i n noodles and spaghetti. The pasta was made from composite flours prepared by blending 33% pea f l o u r with 67% wheat f l o u r or 20% pea concentrate with 80% wheat f l o u r . Protein content of the f o r t i f i e d noodles was approximately one-third higher than the wheat f l o u r noodles. Addition of pea f l o u r reduced the cooking time, but resulted i n a softer product and lower y i e l d than the wheat pastas. Precooking the pea f l o u r improved flavor and decreased noodle dough s t i c k i n e s s , but the texture and y i e l d of the cooked pasta was s t i l l less than that of wheat products. F i e l d Pea Flours i n Bread Products. Legume f l o u r s , p a r t i c u l a r l y soy, have long been incorporated into wheat-based products, both for t h e i r functional e f f e c t s and for protein f o r t i f i c a t i o n . In general, increasing the l e v e l s of legume f l o u r s r e s u l t s i n decreased l o a f volume, lower crumb grain q u a l i t y , and adverse flavor c h a r a c t e r i s t i c s i n the baked bread (Table I I I ) . Results have varied with respect to the amount of f i e l d pea f l o u r that can be incorporated into a yeast bread before an unacceptable product i s produced. T r i p a t h i and Daté (40) made breads containing 5, 10 and 15% f i e l d pea f l o u r and found breads made with more than 5% pea flour were not acceptable. Loaf volume decreased as the percent s u b s t i t u t i o n increased. At the 5% l e v e l , c o l o r , f l a v o r and taste of the breads were rated as excellent, but at the 10 and 15% l e v e l s , there was a b i t t e r taste. Fleming and Sosulski (45) found that the incorporation of f i e l d

PLANT PROTEINS

26

pea concentrates into yeast breads at l e v e l s from 5 to 25% increased the protein content from 10.2% f o r the wheat control to 16.8% at the highest s u b s t i t u t i o n l e v e l . However, s p e c i f i c volume o f the l o a f Table I I I .

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch003

Product

Baked Products Made with F i e l d Pea

Levels of Substitution

Quality

Yeast bread (40)

5, 10, 15% pea f l o u r

Decreased volume Acceptable sensory q u a l i t y at 5% B i t t e r taste at 10 and 15%

Yeast bread (37)

5-20% raw or cooked pea flour

Decreased volume Bleaching e f f e c t with raw pea f l o u r Lower a c c e p t a b i l i t y above 15%

Yeast bread (41)

8 and 15% concentrate

Decreased volume Lower a c c e p t a b i l i t y at 15%

Yeast bread (42)

2.5-10% pea f l o u r

No volume change Acceptable, beany at 10%

Quick bread (43)

5-15% pea f l o u r

No volume change Beany flavor at 10%

B i s c u i t s (44)

8% pea f l o u r

Aroma and flavor decreased Doughy texture

decreased sharply (from 6.04 to 3.56 cc/g) and crumb grain and l o a f shape scores were s t e a d i l y and s i g n i f i c a n t l y decreased with each 5% increment i n soy f l o u r . They observed s i m i l a r r e s u l t s with other plant protein concentrates. The addition of dough conditioners such as sodium stearoyl l a c t y l a t e improved the volumes and crumb grain ratings o f the breads. Sosulski and Fleming (41) also reported that addition of 8 or 15% f i e l d pea f l o u r plus 2% vTFal gluten resulted i n breads that were generally acceptable, p a r t i c u l a r l y at the lower level of substitution. J e f f e r s et a l . (32) used 5, 10, 15 and 20% substitutions of raw and cooked pea f l o u r i n wheat bread. D i f f e r e n t l e v e l s of ΚΒΓΟ3 were incorporated i n the doughs. Mixing times were decreased s i g n i f i c a n t l y when pea f l o u r was used. Mixing tolerance increased at 5 and 10% l e v e l s , but was less at 15 and 20% l e v e l s with the raw pea f l o u r ; cooked pea flour d i d not improve mixing tolerance. Loaf volumes decreased with increasing l e v e l s of pea f l o u r , as did crumb grain scores. However, at the 15% s u b s t i t u t i o n l e v e l s , the breads were nearly standard. Repetsky and Klein (42) found that pea f l o u r s i g n i f i c a n t l y affected the texture, color and flavor of yeast breads. At

3.

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Field-Pea Flours as Protein Supplements

27

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch003

s u b s t i t u t i o n l e v e l s ranging from 2.5 to 10%, l o a f volume and s p e c i f i c volume o f the breads were not s i g n i f i c a n t l y d i f f e r e n t from the wheat f l o u r c o n t r o l . But trained taste panelists detected a beany o f f - f l a v o r i n breads with 10% pea f l o u r , and the color scores were lower than for the c o n t r o l . The baking studies with yeast breads indicate that l e v e l s o f s u b s t i t u t i o n o f up to 15% pea f l o u r or concentrate f o r wheat f l o u r r e s u l t i n breads that are generally acceptable, but are r e a d i l y distinguishable from, and less preferred t o , wheat c o n t r o l s . Although the use o f a cooked or heated pea f l o u r or concentrate improves f l a v o r , the f u n c t i o n a l i t y o f the product i n bread i s adversely a f f e c t e d . F i e l d Pea Flour i n Other Baked Products. When McWatters (44) substituted 8% f i e l d pea f l o u r and 4.6% f i e l d pea concentrate f o r milk protein (6%) i n baking powder b i s c u i t s , sensory a t t r i b u t e s , crumb c o l o r , and density o f the r e s u l t i n g b i s c u i t s were adversely affected. No modifications were made i n recipe formulation when pea products were incorporated. The doughs were s l i g h t l y less s t i c k y than control b i s c u i t s that contained whole milk. This might be due to lack of lactose or to the d i f f e r e n t water absorption properties of pea protein or s t a r c h . Panelists described the aroma and flavor of these b i s c u i t s as harsh, beany and strong. Steam heating the f i e l d pea f l o u r improved the sensory evaluation scores, but they were never equivalent to those f o r the c o n t r o l s . Raidl and Klein (43) substituted 5, 10, and 15% f i e l d pea flour i n chemically leavened quick bread. The v i s c o s i t y o f the pea f l o u r batters was s i g n i f i c a n t l y lower than either the wheat control or soy containing batters. The starch composition o f the pea f l o u r and lower water absorption properties o f the protein could have affected the v i s c o s i t y . Volumes o f pea f l o u r loaves were lower than the control and soy loaves. Most o f the sensory c h a r a c t e r i s t i c s o f the f i e l d pea loaves were s i m i l a r to those o f the control quick breads. However, a l l flavor scores were s i g n i f i c a n t l y lower f o r pea f l o u r products, since they had a recognizably beany or o f f - f l a v o r . Enzymatic Action i n Pea Flour Flavor i s one o f the major c h a r a c t e r i s t i c s that r e s t r i c t s the use o f legume f l o u r s and proteins i n foods. Processing o f soybeans, peas and other legumes often r e s u l t s i n a wide variety o f v o l a t i l e compounds that contribute flavor notes, such as grassy, beany and rancid f l a v o r s . Many o f the objectionable flavors come from oxidative deterioration o f the unsaturated l i p i d s . The lipoxygenasecatalyzed conversion o f unsaturated fatty acids to hydroperoxides, followed by t h e i r degradation t o v o l a t i l e and n o n - v o l a t i l e compounds, has been i d e n t i f i e d as one o f the important sources o f flavor and aroma components o f f r u i t s and vegetables. An enzymea c t i v e system, such as raw pea f l o u r , may have most o f the necessary enzymes to produce short chain carbonyl compounds. Lipoxygenase (linoleate:oxygen oxidoreductase) catalyzes the hydroperoxidation o f f a t t y acids containing a methylene-interrupted conjugated diene system. The degradation o f the hydroperoxides r e s u l t s i n the formation o f numerous secondary products (46-48).

28

P L A N T PROTEINS

The coupled oxidation of carotenoids during lipoxygenase reactions has been exploited i n the baking industry for many years. Enzymea c t i v e soy f l o u r has been used i n breadmaking since the early 1930 s, when Haas and Bonn patented a process for preparing a soy f l o u r for use i n bleaching and dough improvement (49). Carotene oxidation i s a secondary reaction associated with lipoxygenase (48), and the bleaching action occurs r e a d i l y i n a flour-water system. Oxidative improvement of dough that contains enzyme-active f l o u r s i s recognized i n the bakery industry. Small quantities (less than 1% of f l o u r weight) of enzyme-active f l o u r s r e s u l t i n changes i n dough development p r o f i l e s : higher relaxation times i n d i c a t i n g greater dough strength, and delayed peak development providing greater tolerance to overmixing. These changes require oxygen and are r e l a t e d to the release of bound l i p i d s through a lipoxygenasecoupled oxidation of the l i p i d s . The oxidation of gluten occurs simultaneously, an e f f e c t which may also be a t t r i b u t a b l e to lipoxygenase-generated products (1,50). Unheated pea f l o u r s are also e f f e c t i v e i n bleaching and improvement of doughs (37,51). Mixing times are shorter with pea-wheat f l o u r combinations, and mixing tolerance i s increased. The l e v e l s of pea f l o u r that are most e f f e c t i v e for dough improvement are usually less than 5%, and 0.75 to 3% has been recommended. At higher l e v e l s , undesirable dough behavior occurs, as well as flavor d e t e r i o r a t i o n .

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch003

f

Flavor Generation i n Pea Products The v o l a t i l e constituents of raw peas have been studied with respect to the development of desirable and undesirable flavors i n the processed fresh product. Numerous substances have been i d e n t i f i e d (52-54), such as ethanal, propanal, 2-trans-butenal, 2-trans-pentenal, 2-trans-hexenal, heptadienal, nonadienal, 3,5-octadecadiene-2-one, hexanal, pentanol, hexanol, pentanal, nonanal, octanal, and heptanal. The s p e c i f i c compounds that are responsible for the "pea" flavor have not been i d e n t i f i e d . Bengtsson and Bosund (52) suggested that acetaldehyde, hexanal and ethanol were important, while Murray et a l . (53) i s o l a t e d three methoxypyrazines that have very low taste or recognition thresholds and might, therefore, be of major s i g n i f i c a n c e i n pea f l a v o r . In baked products, v o l a t i l e carbonyl compounds have been i d e n t i f i e d as important flavor and aroma constituents (55,56). Sosulski and Mahmoud (57) determined the composition of the major v o l a t i l e carbonyls i n protein supplements, fermented doughs, and i n breads made from protein supplemented f l o u r s . These f l o u r s included f i e l d p e a - f o r t i f i e d wheat f l o u r . Some of the v o l a t i l e s produced i n the yeast breads are shown i n Table IV. Several of the compounds associated with pea flavor are also present i n the breads; t h e i r concentration i s higher i n soy and pea-containing breads than i n u n f o r t i f i e d wheat breads. This suggests that when unheated legume f l o u r s are used as a supplement i n doughs, the r e s u l t i n g flavor and aroma c h a r a c t e r i s t i c s could be a r e s u l t of enzymatic a c t i v i t y , p a r t i c u l a r l y lipoxygenase.

3.

KLEIN A N D RAIDL

Table IV.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch003

Ethanal Propanal 2-Propanone Butanal 2-Butanone 2-Methyl Butanal Unknown Hexanal Furfural + HMF a

29

Field-Pea Flours as Protein Supplements

Carbonyl Compounds i n Yeast Bread (mg/100 g dry weight) (57) a

Wheat

Soy

166 25 982 25 306 107 47 139 600

325 56 1332 38 358 840 151 1096 1470

F i e l d Pea 457 37 1155 37 300 616 599 520 1730

Wheat flour/protein supplement/vital gluten = 83:15:2

Summary The f o r t i f i c a t i o n of cereal-based products with f i e l d pea f l o u r s or protein concentrates r e s u l t s i n an increase i n both quantity and q u a l i t y of protein i n the food. However, the use of pea f l o u r s i s l i m i t e d by some of the less desirable e f f e c t s . At low l e v e l s of f o r t i f i c a t i o n (0.75-1%), unheated pea flour i s an e f f e c t i v e dough improver, improving mixing time and tolerance, and providing bleaching action through lipoxygenase a c t i v i t y . At s l i g h t l y higher l e v e l s , 3 to 6%, i t can be used as a non-fat dry milk r e p l a c e r , although t h i s may require some additives such as v i t a l gluten or potassium bromate. At l e v e l s above 8%, changes i n crumb q u a l i t y appear, and at l e v e l s of 15% and more, where the protein supplementation e f f e c t i s s i g n i f i c a n t , volume, f l a v o r , aroma and o v e r a l l a c c e p t a b i l i t y are a l t e r e d . Heating pea flour or concentrates improves f l a v o r c h a r a c t e r i s t i c s , but the heated product may not r e t a i n the desirable functional properties. Therefore, although f i e l d pea flours and protein concentrates have some technological and economic advantages, t h e i r potential use i n food products w i l l be l i m i t e d u n t i l the f u n c t i o n a l i t y and flavor problems can be resolved. Literature 1.

2. 3. 4.

Cited

Rackis, J. J. In "Enzymes in Food and Beverage Processing"; Ory, R. L.; St. Angelo, A. J., Eds.; ACS SYMPOSIUM SERIES No. 47, American Chemical Society: Washington, D.C., 1977; pp. 244-265. Pimentel, D.; Drischilo, W.; Krummel, J.; Kutzman, J. Science 1975, 190, 754. "National Food Review," Economics, Statistics and Cooperatives, Service A. NFR-9 (Winter), 1980, p. 51. Youngs, C. G. In "Oilseeds and Pulse Crops in Western Canada A Symposium"; Western Cooperative Fertilizers, Ltd.: Calgary, Alberta, Canada, 1977; Chap. 27.

a

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch003

30

P L A N T PROTEINS

5. Reichert, R. D.; Youngs, C. G. Cereal Chem. 1978, 55, 469. 6. Tyler, R. T.; Panchuk, B. D. Cereal Chem. 1984, 61, 192. 7. Watt, Β. K.; Merrill, A. "Composition of Foods," Handbook No. 8; U.S. Department of Agriculture, 1963. 8. Reichert, R. D.; Mackenzie, S. L. J. Agric. Food Chem. 1982, 30, 312. 9. Vose, J. R. Cereal Chem. 1977, 54, 1141. 10. Slinkard, A. E. "Production, Utilization and Marketing of Field Peas"; Development Centre, university of Saskatchewan: Saskatoon, Saskatchewan, Canada, 1977; Ann. Report No. 1. 11. Gottschalk, W.; Mueller, H. P.; Wolff, G. Egypt. J. Genet. Cytol. 1975, 4, 453. 12. Bramsnaes, F; Olsen, H. S. J. Amer. Oil Chem. Soc. 1979, 56, 450. 13. Vose, J. R. Cereal Chem. 1980, 57, 406. 14. McLean, L. A.; Sosulski, F. W.; Youngs, C. G. Can. J. Plant Sci. 1974, 54, 301. 15. Holl, F. B.; Vose, J. R. Can. J. Plant Sci. 1980, 60, 1109. 16. Eppendorfer, W. H.; Bille, S. W. Plant and Soil 1974, 41, 33. 17. Robertson, R. N.; Highkin, H. R.; Smydzuk, J.; Went, F. W. Aust. J. Biol. Sci. 1962, 15, 1. 18. Reichert, R. D. J. Food Sci. 1982, 47, 1263. 19. Holt, N. W.; Sosulski, F. W. Can. J. Plant Sci. 1979, 59, 653. 20. Evans, I. M.; Boulter, D. J. J. Sci. Food Agric. 1980, 31, 238. 21. Derbyshire, E.; Wright, D. J.; Boulter, D. Phytochemistry 1976, 15, 3. 22. "Pea Flour and Pea Protein Concentrates," PFPS Bulletin No. 1, Prairie Regional Laboratory, National Research Council and College of Home Economics, university of Saskatchewan, Saskatoon, Canada, 1974; pp. 617-632. 23. Vose, J. R.; Basterrechea, M. J.; Gorin, P.A.J.; Finlayson, A. J.; Youngs, C. G. Cereal Chem. 1976, 53, 928. 24. Sosulski, F. W.; Elkowics, L.; Reichert, R. D. J. Food Sci. 1982, 47, 498. 25. Biliaderis, C. G.; Grant, D. R. Can. Inst. Food Sci. Technol. J. 1979, 12, 131. 26. Biliaderis, C. G.; Grant, D. R.; Vose, J. R. Cereal Chem. 1979, 56, 475. 27. Biliaderis, C. G.; Grant, D. R.; Vose, J. R. Cereal Chem. 1981, 58, 496. 28. Reichert, R. D. Cereal Chem. 1981, 58, 266. 29. Sosulski, F. W.; Youngs, C. G. J. Amer. Oil Chem. Soc. 1979, 56, 292. 30. Patel, Κ. M.; Bedford, C. L.; Youngs, C. G. Cereal Chem. 1980, 57, 123. 31. Tyler, R. T.; Youngs, C. G.; Sosulski, F. W. Cereal Chem. 58, 144. 32. Tyler, R. T.; Panchuk, B. D. Cereal Chem. 1982, 59, 31. 33. Sumner, A. K.; Nielsen, Μ. Α.; Youngs, C. G. J. Food Sci. 1981, 46, 364. 34. Johnson, D. W. J. Am. Oil Chem. Soc. 1969, 47, 402. 35. Quinn, J. R.; Paton, D. Cereal Chem. 1979, 56, 38. 36. Vaisey, M.; Tassos, L.; McDonald, Β. E. Can. Inst. Food Sci. Technol. J. 1975, 8(2), 74.

3.

KLEIN A N D RAIDL

37. 38. 39. 40. 41. 42. 43. 44. 45. 46.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch003

47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57.

Field-Pea Flours as Protein Supplements

31

Jeffers, H. C.; Rubenthaler, G. L.; Finney, P. L.; Anderson, Ρ. D.; Buinsmas, B. L. Baker's Dig. 1978, 52(6), 36. Hannigan, K. J. Food Engineering Int'l. 1979, 4(2), 22. Nielsen, Μ. Α.; Sumner, A. K.; Whalley, L. L. Cereal Chem. 1980, 57, 203. Tripathi, B. D.; Daté, W. B. Indian Food Packer 1975, 29(3), 66. Sosulski, F. W.; Fleming, S. E. Baker's Dig. 1979, 53(6), 20. Repetsky, J. Α.; Klein, B. P. J. Food Sci. 1981, 47, 326. Raidl, Μ. Α.; Klein, B. P. Cereal Chem. 1983, 60, 367. McWatters, Κ. H. Cereal Chem. 1980, 57, 223. Fleming, S. E.; Sosulski, F. W. Cereal Chem. 1977, 54, 1124. Eskin, N.A.M.; Grossman, S.; Pinsky, A. CRC Crit. Rev. Food Sci. Nutr. 1977, 9, 1. Vliegenthart, J.F.G.; Veldink, G. A. In "Free Radicals in Biology"; Pryor, W. Α., Ed.; Academic: New York, 1982; Vol. V, pp. 29-64. Klein, B. P.; King, D.; Grossman, S. Adv. Free Radical Biol. and Med. 1985, 1, 309. Wolf, W. J. J. Agric. Food Chem. 1975, 23, 136. Frazier, P. J. Baker's Dig. 1979, 53(12), 8. American Institute of Baking, Report to Dumas Seed Company, 1978. Bengtsson, B.; Bosund, I. Food Technol. 1964, 18, 773. Murray, K. E.; Shipton, J.; Whitfield, F. B.; Last, J. H. J. Sci. Food Agric. 1976, 27, 1093. Ralls, J. W.; McFadden, W. H.; Seifert, R. M.; Black, D. R.; Kilpatrick, P. W. J. Food Sci. 1965, 30, 228. Lorenz, K.; Maga, J. A. J. Agric. Food Chem. 1972, 20, 211. Ng, H.; Reed, D. J.; Pence, J. W. Cereal Chem. 1960, 37, 638. Sosulski, F. W.; Mahmoud, R. M. Cereal Chem. 1979, 56, 533.

RECEIVED December 26, 1985

4 Applications of Vegetable Food Proteins in Traditional Foods E. W. Lusas and K. C. Rhee

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch004

Food Protein Research and Development Center, Texas A & M University, College Station, TX 77843

On a world wide basis, man obtains approximately 70% of his daily protein intake from plant sources and 30% from animal and fish sources. These figures are 50 and 50%, respectively, for the developed nations, and 83 and 17% for the developing countries. Oilseeds and pulses (dry beans, lentils and peas) are concentrated sources of proteins, and are expected to play increasingly important roles in human nutrition as world population grows. Whole oilseeds and legumes and their derivatives (defatted flours, and protein concentrates and isolates) are used in traditional foods as sources of protein and for their texture-modifying functions. This article reviews, on a comparative basis, processes for preparation of vegetable food proteins, compositions and characteristics of the resulting food ingredients, and their functionalities and uses in traditional foods. The pulses and c e r t a i n oilseeds (soy, peanuts, sunflower seed, sesame, and glandless cottonseed) were f i r s t accepted by man f o r t h e i r storage s t a b i l i t y , high nutrition-to-weight r a t i o , and a t t r a c tiveness of the foods that can be made from them. Much of the current i n t e r e s t i n uses of derived o i l s e e d proteins i n compounded foods stems from projects i n the mid-1960 s t o a l l e v i a t e massive world hunger. Perhaps the best known of these was the development of Incaparina at the I n s t i t u t e f o r N u t r i t i o n o f Central America and Panama, i n Guatemala by Bressani and coworkers (1). However, many other vegetable protein-enriched mass feeding foods also have been developed, and have been reviewed {2, 3). In developing low cost mass feeding foods, attempts were made t o use l o c a l l y available o i l s e e d cakes and meals whenever possible. In time, i n t e r e s t turned t o the extraction o f high protein content ,

0097-6156/ 86/ 0312-0032$06.00/ 0 © 1986 American Chemical Society

4. LUS AS A N D RHEE

Vegetable Food Proteins in Traditional Foods

33

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch004

ingredients from other processing residues and n o n t r a d i t i o n a l crops. Prejudices once existed against pulses and c e r t a i n oilseeds as foods of the poorest of the poor. However, with world-wide i n t e r e s t i n physical f i t n e s s and dietary f i b e r , and concerns about possible r e l a t i o n s between animal p r o t e i n comsumption and atherosclerosis (£, _5), i n t e r e s t i n food uses of vegetable food proteins i s increasing. Each ingredient i n a compounded food i s selected for a s p e c i f i c purpose. Even the l e s s c o s t l y , low p r o t e i n , ingredients play important roles as sources of t o t a l s o l i d s . For example, the Recommended Daily Allowance (RDA) of 65 g protein i s the equivalent of 260 calor i e s . In a 2600 c a l o r i e d i e t , t h i s amount of p r o t e i n can be d i l u t e d among a t o t a l c a l o r i c intake ten times greater. In addition t o serving the function f o r which i t was selected, each ingredient must not i n t e r f e r e undesireably with the functions of other ingredients also present. PROCESSING In i t s common use, the term "vegetable food p r o t e i n " usually means a processed or derived o i l s e e d ingredient, l i k e defatted f l o u r and the higher protein content concentrate and i s o l a t e forms. Almost every defatted, dehulled o i l s e e d f l o u r contains over 50% protein (dry weight b a s i s ) . The terminology of soybean food proteins has essent i a l l y been adopted for other o i l s e e d s : "protein concentrate" t y p i c a l l y means a product containing over 70% protein (dry weight b a s i s ) , and a "protein i s o l a t e " contains over 90% p r o t e i n . For a i r - c l a s s i f i e d ingredients, "concentrate" refers t o f r a c t i o n s that contain more protein than the o r i g i n a l seed. Since f u l l - f a t or defatted f l o u r s , l i k e those of soy, can impart undesireable f l a v o r s , the more p u r i f i e d food proteins ingredients l i k e concentrates and i s o l a t e s are p r e f e r red f o r c e r t a i n a p p l i c a t i o n s . F u l l - f a t Products A flowsheet f o r preparation of glandless cottonseed f u l l - f a t kernels and subsequent processing of defatted f l o u r s and concentrates and i s o l a t e s i s shown i n Figure 1. This scheme, with s p e c i a l i z e d adaptations depending upon o i l s e e d species, i s t y p i c a l f o r processing of a l l oilseeds. F u l l - f a t g r i t s simply consist of whole and broken kernels that have been size-reduced by passing through c u t t i n g r o l l s or a hammer m i l l , and c l a s s i f i e d by s i e v i n g . Flakes are made by conditioning whole kernels or g r i t s with moisture and heat to a s s i s t t h e i r p l a s t i c i z a t i o n , and then passing through narrowly-set smooth r o l l s t o achieve the desired thickness. The advantage o f g r i t s and flakes i s that flowable ingredients can s t i l l be had, even from high o i l content seeds. T y p i c a l l y , f u l l - f a t f l o u r s are made by hammer m i l l i n g the seed to pass through 80-mesh or smaller s i z e screens. However, grinding of oilseeds containing over 25% o i l r e s u l t s i n s t i c k y f l o u r s . Thus, p a r t i a l l y - d e f a t t e d peanut and sunflower seed f l o u r s are made by f i r s t screw pressing the seed t o reduce the o i l t o 6-18% f a t content. I t i s common p r a c t i c e t o s t a b i l i z e f u l l - f a t products by preheating the seed, or by extrusion as i n the case of f u l l - f a t soybean f l o u r (6). Heat treatment deactivates l i p a s e s and lipoxygenases

34

PLANT PROTEINS

Ginned Glandle^ss Cottonseed Cleaning Conditioning of Fuzzy Seed

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch004

Denuding - Separation Kernels

Hulls

Sizing Kernels

1

Middles

Fines

~

Roasting (Optional)

r

Conditioning Color Sorting (Optional) Accepted Kernels

Flaking Solvent Extraction

ι—

Rejected Kernels

Marc

Desolventizing

r Concentrate, Isolate Preparation Raw or Roasted Kernels Figure 1.

Animal Feed

J Grinding Τ

Mlscella Solvent Recovery

Extracted Flakes

Defatted Flour

Crude Oil

General flow chart f o r production of glandless cottonseed food i n g r e d i e n t s .

4. LUSAS AND RHEE

Vegetable Food Proteins in Traditional Foods

35

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch004

which catalyze development of free f a t t y acids and o f f f l a v o r s , r e s p e c t i v e l y , i n addition t o deactivating a n t i n u t r i t i o n a l factors such as t r y p s i n i n h i b i t o r s , hemagglutinins and other l e c t i n s . A l i m i t e d amount of enzyme-active f u l l - f a t soybean f l o u r i s sold f o r bleaching and conditioning of wheat f l o u r and bakery products (7). High o i l content seeds form pastes upon grinding, the best known example being peanut butter, which accounts f o r approximately 55% of domestic uses o f peanuts. By law, peanut butter consists of a minimum of 90% peanuts, with the remainder being e m u l s i f i e r s and/or hydrogenated f a t s t o prevent o i l i n g - o f f during storage, and s a l t , sweeteners and f l a v o r i n g s . I t i s t y p i c a l t o blanch (remove the pink/red s k i n or "testa") , roast, s p l i t , and remove the germ t o reduce b i t t e r f l a v o r from peanut kernels before grinding i n t o peanut butter. Defatted Flours Defatted f l o u r s are made by e x t r a c t i n g cleaned, dehulled o i l s e e d kernels i n o i l m i l l s that are sanitary i n design and operation f o r production of food-quality ingredients. When kernels contain less than 35% o i l ( l i k e soybeans and glandless cottonseed) , the seed may be conditioned, flaked and extracted d i r e c t l y with food grade commerc i a l hexane. Flakes of high o i l content kernels (peanuts and sunflower seed) w i l l not remain i n t a c t during solvent e x t r a c t i o n . I t i s t y p i c a l to prepress these seeds to an o i l content of approximately 16% and then solvent extract the broken or reflaked press cake. A f t e r countercurrent e x t r a c t i o n , the hexane i s drained and the meal desolventized and toasted by heat. The extent of toasting greatly a f f e c t s protein s o l u b i l i t y of the meal, and a range of soy f l o u r s with p r o t e i n d i s p e r s i b i l i t y indexes (PDI's) from 90 t o 20% i s a v a i l able. Defatted dehulled meals are converted into f l o u r s by ginding to pass though a 100 mesh screen. In producing sunflower f l o u r , 95% removal of h u l l s (grey and white striped) from confectionery v a r i e t i e s , and 97% removal of h u l l s from o i l - t y p e (black h u l l ) v a r i e t i e s i s necessary t o avoid noticeable grayness i n the f l o u r . Extraction also has the e f f e c t of concentrating the r e l a t i v e percentages of components remaining i n the meal. Upon e x t r a c t i o n , gossypol content i n glandless cottonseed f l o u r and chlorogenic acid content i n sunflower seed f l o u r can be increased by nearly 50 and 100%, respect i v e l y , from the o r i g i n a l contents i n kernels because these compounds are not soluble i n hexane and stay with the meal. Concentrates Concentrates are made by extracting water-soluble sugars and other compounds from defatted meals or f l o u r s . This i s t y p i c a l l y a secondary e x t r a c t i o n , using a c i d i c ethanol-water i n a chain-type or basket-type continuous extractor f o r processing f l a k e s , or a c i d i c water e x t r a c t i o n of f l o u r i n vats, followed by spray-drying (8). A c i d i c polar solvents are used at or near the i s o e l e c t r i c point of the p r o t e i n t o minimize i t s s o l u b i l i t y and l o s s . The reextracted flakes may then be ground i n t o a f l o u r . Concentrates are more bland than defatted f l o u r s , but s t i l l contain the f i b e r components of the kernel. A f t e r e x t r a c t i o n with a c i d i c ethanol or water, concentrates

36

PLANT PROTEINS

may be neutralized to pH 6-7 to improve t h e i r s o l u b i l i t y and functionality. Isolates

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch004

Isolates t y p i c a l l y are made by s o l u b l i z i n g protein from defatted flakes with a l k a l i , removing the insoluble components by decanter or desludging centrifuge, p r e c i p i t a t i n g the protein at i t s i s o e l e c t r i c pH, concentrating the p r e c i p i t a t e by c e n t r i f u g a t i o n , and spray-drying the p r e c i p i t a t e f r a c t i o n . In some instances, pH of the acid p r e c i p i tate i s adjusted to near n e u t r a l i t y with sodium hydroxide to produce a "proteinate". Cottonseed protein i s unique i n having two f r a c t i o n s , "storage p r o t e i n " and "nonstorage p r o t e i n " , that can be r e a d i l y fractionated by p r e c i p i t a t i o n at selected pH's (9) Aqueous Extraction One of the e a r l i e s t methods of o i l extraction practiced by man was to mix f i n e l y ground dehulled seed i n hot water and skim o f f the layer of o i l which separated and rose to the surface of the vat. This process has been modernized by using mechanical grinders, s t a i n l e s s s t e e l extraction tanks, 3-phase centrifuges and spray dryers, and i s c a l l e d "aqueous extraction processing" (AEP). In t h i s procedure, the o i l i s removed as an emulsion which i s l a t e r broken by various means. The p r o t e i n remaining i n the l i q u i d may then be recovered and spray dried as protein concentrates or i s o l a t e s . To date, the following oilseeds have been extracted experimentally by AEP: soybeans (10) , glandless cottonseed (11), peanuts (12), sunflower seed (13), sesame (14), lupine (15), and coconuts U 6 ) . At the current state of the a r t , minimum achievable r e s i d u a l o i l contents i n AEP concentrates are: soybeans, 4-6%; glandless cottonseed, 6-8%; sunflower seed, 4-6%; peanuts 1-2%; and sesame 2-3%. However, the r e s i d u a l o i l s i n AEP f l o u r s , concentrates and i s o l a t e s are remarkably stable. I n d u s t r i a l Membrane Processing A v a r i e t y of processing options i s p o s s i b l e through i n d u s t r i a l membrane processing (IMP). U l t r a f i l t r a t i o n (UF) membranes of 20,000 molecular weight (MW) cutoff allow holding back of proteins (as retentate), while the sugars and water-soluble compounds pass through (as permeate). The permeate can then be processed by reverse osmosis (RO) to obtain e s s e n t i a l l y pure water as RO permeate, and the soluble compounds concentrated to about 20% s o l i d s as RO retentate. Experimental processes f o r producing soy concentrates and i s o l a t e s (17) , glandless cottonseed concentrates and i s o l a t e s (18), and peanut protein concentrates and i s o l a t e s (19) have been described. Various combinations of t r a d i t i o n a l IMP and AEP/IMP techniques also have been t r i e d i n preparation of vegetable protein concentrates and i s o l a t e s . COMPOSITION Protein contents of selected oilseeds and legume seeds, and food protein ingredients prepared by various procedures, are shown i n Table I. Amino acid contents and protein e f f i c i e n c y r a t i o s (PER's)

90

90

91

92

93

Protein Isolate

a

Protein Isolate

b

92

87 80°

—

Storage protein; Nonstorage protein; °Air-classified high-protein fraction.

71

68

Protein Concentrate

71

—

87

89

91

92

86

Protein Isolate

Membrane Process

71

68

67

70

68

Protein Concentrate

— —

52

77

70

71

71

72

Protein Concentrate

Aqueous Extraction Process

43

50

48

63

52

55

Defatted Flour

Classical Process

C

—

— —

—

53

43 C

29

30

26

24

43

30

43

Dehulled Seed (Kernel)

26

26

18

20

39

27

34

Whole Seed

Pinto Beans

Navy Beans

Sesame

Glandless Cottonseed

Peanuts

Soybeans

Fractions

Sunflower Seed

Table I. Percent Protein Content of Various Fractions of Several Oilseeds and Legumes

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch004

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch004

38

PLANT PROTEINS

of selected food protein ingredients are presented i n Table I I . Typical h u l l contents of seeds are: soybeans, 8-10%; peanuts (shells and t e s t a s ) , 20-30%; fuzzy cottonseed ( l i n t e r s and h u l l s ) , 40-50%; sunflower seed, 20-25%; sesame, 15-20%; and dry f i e l d beans, 8-10%. Typical o i l contents of dehulled kernels (and f u l l - f a t flours) are: soybeans, 20-23%; peanuts, 50-55%; glandless cottonseed 35-38%; sunflower, 50-55%; peeled sesame, 45-63%; and beans, 1-3%. Total carbohydrate contents of defatted f l o u r s are: soybeans, 26-30%; peanuts, 25-30%; glandless cottonseed, 23-27%; sunflower, 25-29%; sesame, 26-30%; and beans, 60-65%. Phytate contents of defatted f l o u r s are: soybeans 1.4-1.6%; peanuts, 1.7%; glandless cottonseed, 2.3-4.8%; sunflower, 1.5-1.9%; sesame, 3.6-5.2%; and beans, 1.4-1.8%. Trypsin i n h i b i t o r contents of dehulled kernels are: soybeans, 4-6%; peanuts, 0.8-1.5%; glandless cottonseed, 0.5-1.5%; sunflower, 0.71.8%; sesame, 0.5-0.8%; and beans, 2-3%. The U. S. Food and Drug Administration has set a l i m i t of 450 ppm free gossypol i n glandless cottonseed kernels and f l o u r , and the United Nations FAO/WHO has set l i m i t s of 600 ppm free gossypol and 1.2% t o t a l gossypol i n cottonseed products used f o r human feeding. FUNCTIONALITY Food protein ingredients are sometimes evaluated by comparative empirical t e s t s , including: nitrogen s o l u b i l i t y index (NSI) and protein d i s p e r s i b i l i t y index (PDI) p r o f i l e s over a range of pH's, water absorption, v i s c o s i t y , g e l l i n g strength, whipping and foaming c a p a b i l i t y (including volume and s t a b i l i t y of foam); f a t absorption, and o i l e m u l s i f i c a t i o n . Performance (including f l a v o r , texture and v i s u a l appeal) i s often evaluated p h y s i c a l l y using standardized food formulations, including bread (loaf volume, crumb and crust color and texture); sugar cookies (sheet spread, surface cracking), frankfurters (fat e m u l s i f i c a t i o n s t a b i l i t y , swelling and d r i p loss i n cooking, firmness and p e e l a b i l i t y ) ; meat loaves (moisture and f a t retent i o n during cooking); and frozen desserts (overrun and texture). However, the most meaningful evaluations are d i r e c t in-product trials. Proteins h i s t o r i c a l l y have been c l a s s i f i e d on the basis of t h e i r s o l u b i l i t y i n water (albumins); s a l t s o l u t i o n (globulins); alcohol (prolamines) and a l k a l i (glutelins) (20). Texture f u n c t i o n a l i t y of food proteins i s affected by many f a c t o r s , including r e l a t i v e proportions of the subfractions recovered by e x t r a c t i o n , and by s o l u b i l i t y as affected by heating or toasting. Also, i t should be remembered that most food products are complex systems with i n t r i n s i c pH and s a l t s o l u b i l i z a t i o n e f f e c t s , and that heat during product processing may coagulate and/or reduce s o l u b i l i t y of a l l proteins present, regardless of source. S o l u b i l i t y curves of proteins from s i x raw f l o u r sources are shown i n Figure 2. UTILIZATION F u l l - F a t Products Nut uses of roasted peanuts and sunflower kernels and deep f a t f r i e d soybean "nuts" are w e l l known. A s u b s t a n t i a l amount of vegetable protein i s consumed i n the

1.9 1.9 1.8 1.0 0.9

5.6 4.9 3.7 1.9 1.8

10.6 8.4 7.9 7.7 6.7

3.9 3.6 3.3 4.0 3.8

4.7 4.2 3.6 4.2 5.0

4.6 4.5 4.6 4.6 5.4

7.4 7.1 6.6 7.6 7.5

4.2 4.2 4.1 3.5 3.0 2.1 7.2 6.5

Sesame Defatted Flour Concentrate Isolate

Whole Navy Bean Flour

Whole Pinto Bean Flour

7.2 6.9 6.4

5.7 5.7 5.5

4.5 4.9 4.7 4.6 4.6 4.5 4.6 4.3

3.1 3.2 3.2 3.4 3.0 3.9 3.7 3.7

3.2 3.1 3.2 3.4 2.6

2.6 2.5 2.5

8.7 8.7 8.6

8.5 8.8 8.7 7.4 9.2

8.4 10.0 9.9

3.6 3.6 3.4

3.8 3.5 3.7 5.0 2.4

1.9 2.4 2.4

3.2 3.0 2.1

Sunflower Seed Defatted Flour Concentrate Isolate

6.0 6.2 6.1 6.4 5.6

3.2 4.3 3.6

8.9 9.1 9.1

4.0 4.0 4.0 6.2 2.9

5.3 4.5 4.4

4.3 4.2 3.7

Glandless Cottonseed Defatted Flour Concentrate Isolate, Classical Nonstorage Protein Storage Protein

6.4 6.7 6.6

5.1 4.8 4.9

3.0 3.0 3.0

5.4 4.9 4.8

Peanut Defatted Flour Concentrate Isolate

7.7 7.8 7.7

6.9 6.3 6.1

Soybean Defatted Flour Concentrate Isolate

1.1 1.0 1.0

1.5 1.5 1.5 1.6 1.0

1.0 1.1 1.0

1.3 1.5 1.4

1.0

3.5

6.0

4.0

4.0

5.0

7.0

5.5

FAO/WHO Reference Protein

Try

Met+Cys

Phe+Tyr

Thr

lieu

Val

Leu

Essential Amino Acid

Essential Amino Acid Profilée (g/16g N) and Protein Efficiency Ratios of Various Protein Food Ingredients

Lye

Table II.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch004

1.7 1.6 1.4

2.1 2.0 1.9

2.2 2.0 1.8 2.4 1.6

1.8 1.6 1.4

2.2 1.8 1.6

—

PER

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch004

40 PLANT PROTEINS

4.

LUSASANDRHEE

Vegetable Food Proteins in Traditional Foods

41

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch004

form of whole seeds and f u l l - f a t products. Examples of whole seed uses include peanuts i n nut-form or i n confections, sunflower seed of the loose-shelled "confectionery" type (21); sesame seed used as bread and bun toppings and f o r breads and buns (22); roasted soybean nuts (7); and the more recently introduced glandless cottonseed kernels used i n confections, toppings f o r i c e cream novelties and salad bars, and i n s p e c i a l t y breads l i k e Proteina bread. The Food Protein Research and Development Center at Texas A&M University has developed a cookbook of glandless cottonseed kernel uses i n a v a r i e t y of appetizer, salad, main course, side d i s h , and dessert products (23). The only f u l l - f a t o i l s e e d f l o u r with s i g n i f i c a n t domestic sales i s soy. I t has been used i n bakery products, breakfast cereals, canned baby foods, canned i n f a n t formulas f o r l a c t o s e - i n t o l e r a n t babies, and adult dietary beverages Ç24). Bakery Products Baked goods are the oldest known compounded foods made by mankind. Each ingredient i s selected f o r one or more s p e c i f i c purposes based on contribution to f u n c t i o n a l i t y and c o m p a t i b i l i t y , and on r e l a t i v e cost. Bakery products formulators are receptive to new ideas, and vegetable proteins (primarily f l o u r s and concentrates) have been well-accepted when they show a cost advantage, f o r example, soy f l o u r s as replacements f o r dried nonfat milk s o l i d s and d r i e d eggs. Defatted f l o u r s are e s p e c i a l l y a t t r a c t i v e as protein sources , since 10-12% s u b s t i t u t i o n of wheat f l o u r with 50% protein f l o u r w i l l r a i s e t o t a l p r o t e i n content of t y p i c a l wheat breads by approximately 50%, and 25% s u b s t i t u t i o n w i l l almost double the protein content of cookies. Preparation of protein-enriched breads has been reported i n the l i t e r a t u r e using soy f l o u r s and p r o t e i n concentrates (25), peanut f l o u r s and peanut protein concentrates (2£, 27), glandless cottonseed f l o u r s , concentrates and i s o l a t e s (28) , sunflower seed f l o u r s and seed p r o t e i n concentrates (27) and sesame f l o u r s and p r o t e i n concent r a t e s (26) . Generally, vegetable food p r o t e i n ingredients are more absorbant than other dough components, with the r e s u l t that mixing time and l o a f volume i s decreased. In a d d i t i o n , pan bread crumb becomes coarser and occasionally darker i n color. Negative e f f e c t s on loaf volume appear to be inversely r e l a t e d to p h y t i c a c i d content. The maximum amounts of vegetable food p r o t e i n f l o u r s that can be substituted i n bread without a f f e c t i n g loaf volume and texture are 5-10% (depending upon the source) , and 18-20% can be substituted i n cookies without a f f e c t i n g spread and surface c h a r a c t e r i s t i c s (26). The quantity of vegetable p r o t e i n f l o u r that can be accommodated i n bread can be increased s u b s t a n t i a l l y by pre-toasting and by the use of approximately 1.5% sodium stearoyl 2 - l a c t y l a t e (28) and other emulsifiers. Breakfast Cereals Soy f l o u r s and concentrates are used i n compounded breakfast cereals, p r i m a r i l y f o r improving t o t a l p r o t e i n content and PER. In the absence of dry nonfat milk s o l i d s , glucose i s often included i n bakery products formulations to impart a toasted brown c o l o r . Most

42

PLANT PROTEINS

ready-to-eat breakfast cereals are e i t h e r extruded d i r e c t l y from doughs, or are f i r s t p e l l e t i z e d by extrusion, then flaked by r o l l s before toasting i n continuous ovens. Thus, i t i s r e l a t i v e l y simple to incorporate vegetable protein ingredients i n these products.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch004

Extruded Products Soy proteins are commonly extruded as intermediate forms f o r l a t e r use i n processed foods. Flours and concentrates are t e x t u r i z e d to resemble meat chunks and are sold under the names of Texturized Vegetable Protein (TVP), or texturized soy p r o t e i n (TSP). After rehydration with water (to approximately 18% p r o t e i n and 60-65% moisture content), up to 30% reconstituted soy protein can be used i n ground meat blends i n the school lunch program, and i n m i l i t a r y and other federal-sponsored feeding programs. These products are also used as meat enhancers i n standard of i d e n t i t y canned stews and c h i l i , and as meat extenders and replacers i n nonstandardized products such as p i z z a toppings and sauces, and i n "meatless" products l i k e taco f i l l i n g and "Sloppy Joes". Textured peanut (29), sunflower seed, and glandless cottonseed (30) f l o u r products have been prepared experimentally, demonstrating the v e r s a t i l i t y of extrusion t e x t u r i z a tion. Processed Meat Products The U. S. Department of Agriculture permits up to 3.5% soy f l o u r or soy concentrate i n standard of i d e n t i t y f r a n k f u r t e r s , up to 8% soy f l o u r i n scrapple and c h i l i con came, and up to 2% soy protein i s o l a t e (containing titanium dioxide-TiO as a tracer material) i n standard of i d e n t i t y frankfurters. Soy f l o u r s and concentrates can bind up to 3 times t h e i r weight of water, compared to nonfat dry milk s o l i d s which t y p i c a l l y bind only equal weights of water. A general p r a c t i c e i n evaluating new vegetable food protein sources i s to compare t h e i r performance to soy f l o u r i n frankfurters Ç31). An extruded soy protein i s o l a t e f i b e r product i s also used f o r s t r u c t u r ing mechanically deboned meats, p o u l t r y , f i s h and seafoods i n t o r o l l s , s t i c k s or f i l l e t s , or i n t o extruded shrimp shapes. USDA regulations also allow use of non-meat proteins i n products such as pumped ham and corned beef, provided the f i n i s h e d product contains a minimum protein content of 17%. Pumping to achieve a cooked y i e l d of 130% i s permitted (32). Dairy Products Cow's milk, extended with f u l l - f a t soy f l o u r , i s produced by CIATECH i n Chihuahua, Mexico, and a peanut isolate-extended water b u f f a l o milk ("Miltone") has been produced i n India f o r approximately 20 years Ç33). Establishment of soymilk plants i n Southeast A s i a and L a t i n America i s a growth industry and soy milks also are sold i n the United States. Various beverages, flavored to mask the taste of soybeans, have been introduced world-wide during the l a s t two decades. A major problem of vegetable proteins i s that, being globul i n s , they are r e a d i l y p r e c i p i t a t e d by calcium f o r t i f i c a t i o n , r e q u i r ed under domestic law f o r milk replacement products. Whereas consumers i n other countries r e a d i l y accept shaking of beverage containers

4. LUSAS AND RHEE

Vegetable Food Proteins in Traditional Foods

43

before drinking, the domestic market prefers products which do not s e t t l e . Research progress has been made on succinylation and maleyl a t i o n o f soy, peanut and glandless cottonseed proteins t o prevent t h e i r p r e c i p i t a t i o n i n the presence of calcium f o r t i f i c a t i o n (34). Considerable i n t e r e s t has been shown i n uses o f vegetable food proteins i n cheese-type products. Attempts have been made to coprec i p i t a t e casein and vegetable protein i n the t y p i c a l vat process f o r making cheeses (_35). Rhee (36) has found that up t o 50% peanut protein i s o l a t e and 25% soybean i s o l a t e can be e f f e c t i v e l y s u b s t i tuted f o r sodium caseinate i n the preparation of i m i t a t i o n cheeses.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch004

Summary The invention o f new food forms i s not required to increase uses of vegetable food proteins i n the American d i e t . Uses o f f l o u r s , contrâtes and i s o l a t e s continue t o grow as increasingly more convenience foods are formulated and produced i n f a c t o r i e s , e i t h e r f o r grocery or i n s t i t u t i o n a l sales. REFERENCES 1. 2.

3. 4. 5. 6. 7. 8.

9.

10. 11. 12.

Bressani, R.; Elias, L. G.; Aguirre, Α.; Scrimshaw, N. S., J. Nutr. 1961, 74, 201-208. Orr, Ε., "The Use of Protein-rich Foods for the Relief of Malnutrition in Developing Countries: An Analysis of Experience"; Tropical Products Insti­ tute Monograph G 73, 1972; Aug. Aguilera, J. M.; Lusas, E. W., J. Am. Oil Chem. Soc. 1981, 58(3), 514-520. Carroll, Κ. K., J. Am. Oil Chem. Soc. 1981, 58(3), 416-419. Kritchevsky, D., J. Am. Oil Chem. Soc. 1979, 56(3), 135-140. Mustakas, G. C.; Albrecht, W. J.; Bookwalter, G. N.; McGee, J. E.; Kwolek, W. F.; Griffin, E. L., Jr. Food Technol. 1970, 24, 1290-1296. Circle, S. J.; Smith, Α. Κ., In "Soybeans: Chem­ istry and Technology"; Smith, A. K.; Circle, S. J., Eds; AVI Publ. Co., Westport, 1978. Campbell, M. F.; Kraut, C. W.; Yackel, W. C.; Yang, H. S. In "New Protein Foods"; Altschul, A. M.; Wilcke, H. L., Eds.; Academic Press, New York, 1985; Chap. IX. Martinez, W. H.; Hopkins, D. T. In "14th Nutri­ tional Quality of Foods and Feed. Part II. Ouality Factors: Plant Breeding, Composition, Processing, and Anti-Nutrients."; Friedman, M., Ed.; Marcel Dekker, New York, 1975; pp. 355-374. Rhee, K. C.; Cater, C. M.; Mattil, K. F. U. S. Patent 4 151 310, 1979. Cater, C. M.; Rhee, K. C.; Hagenmaier, R. D.; Mattil, K. F., J. Am. Oil Chem. Soc. 1974, 51(4), 137-141. Rhee, K. C.; Mattil, K. F.; Cater, C. Μ., Food Eng. 1973, 45(5), 82-86.

P L A N T PROTEINS

44

13. 14. 15. 16.

17. 18.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch004

19. 20. 21.

22. 23.

24. 25. 26. 27. 28. 29. 30. 31.

32.

33.

34. 35.

36.

Hagenmaier, R. D., J . Am. O i l Chem. Soc. 1974, 51(10), 470-471. Chen, S. L. M.S. Thesis, Texas A&M University, College Station, 1976. Aquilera, J . M.; Gerngross, M. F.; Lusas, E. W., J . Fd. Technol. 1983, 18, 327-333. Rhee, K. C.; Lusas, E. W. In "Tropical Foods: Chemistry and Nutrition"; Inglett, G. E.; Charalambous, G., Eds.; Academic Press, New York, 1979, Vol.2, pp. 463-484. Lawhon, J . T.; Lusas, E. W., Food Technol. 1984, 38(12), 97-106. Lawhon, J . T.; Manak, L. J . ; Lusas, E. W., J . Food S c i . 1980, 45, 197-203. Lawhon, J . T.; Manak, L. J . ; Rhee, K. C.; Lusas, E. W., J . Food S c i . 1981, 46, 391-398. Vickery, H. B., Physiol. Revs. 1945, 25, 347. Lusas, E. W. In "New Protein Foods"; A l t s c h u l , A. M.; Wilcke, H. L. Eds.; Academic Press, New York, 1985; Chap. XII. Johnson, L. Α.; Sulerman, T. M.; Lusas, E. W., J . Am. O i l Chem. Soc. 1979, 56(3), 463-468. Simmons, R. G.; Golightly, Ν. Η., "Cottonseed Cookery"; Food Protein R&D Center, Texas A&M University, College Station, 1981. Dubois, D. K.; Hoover, W. J . , J . Am. O i l Chem. Soc. 1981, 58(3), 343-346. Rooney, L. W.; Gustafson, C. B.; Clark, S. P.; Cater, C. M., J . Food S c i . 1972, 37, 14-18. Khan, M. N.; Rhee, K. C.; Rooney, L. W.; Cater, C. M., J . Food S c i . 1975, 40(2), 580-583. Khan, M. N.; Lawhon, J . T.; Rooney, L. W.; Cater, C. M., Cereal Chem. 1976, 53(3), 388-396. Khan, M. N.; Wan, P. J . ; Rooney, L. W.; Lusas, E. W., Cereal Foods World 1980, 25(7), 402-404. Aquilera, J . M.; Rossi, F.; Hiche, E.; Chichester, C. O., J . Food S c i . 1980, 45(2), 246-254. Taranto, M. V.; Meinke, W. W.; Cater, C. M.; M a t t i l , K. F., J . Food S c i . 1975, 40, 1264-1269. Smith, G. C.; Juhn, H. I.; Carpenter, Z. L.; M a t t i l , K. F.; Cater, C. M., J . Food S c i . 1973, 38, 849-855. "National School Lunch Program: Special Food Service Program f o r Children"; Federal Register 39(60), 1197. Chandrasekhara, M. R.; Ramanna, B. R.; Jagannath, K. S.; Ramanathan, P. R., Food Technol. 1971, 25, 596-598. Choi, K. R.; Lusas, E. W.; Rhee, K. C., J . Food S c i . 1982, 47, 1713-1716. Rhee, K. C.; Lusas, E. W., In "Annual Report"; Food Protein R&D Center, Texas A&M University, College Station, 1985. Rhee, K. C., In "Annual Report"; Food Protein R&D Center, Texas A&M University, College Station, 1985.

RECEIVED January 24, 1986

5 Uses of Soybeans as Foods in the West with Emphasis on Tofu and Tempeh Hwa L. Wang

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch005

Northern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Peoria, IL 61604

Soybeans have been used as food in the Orient since ancient times and various methods have been developed to make soybeans as palatable as possible. In recent years, a large number of these simply processed soyfoods are emerging in the West. Tofu and tempeh are the most popular and have the fastest growth rate of any soyfood in America. Tofu is made by coagulating the protein with a calcium or magnesium salt from a hot-water extracted, protein-oil emulsion of whole soybeans. It is a highly hydrated gelatinous product with a bland taste. The texture characteristics of the curds vary from soft to firm, depending on the processing conditions. Thus, tofu can be easily incorporated with other foodstuffs and used in nearly every culinary context from salad to dessert and from breakfast foods to dinner entrees. Tempeh is made by fermenting cooked soybeans with a mold, Rhizopus oligosporus. The white mycelium covers the bean mass and binds i t into a firm cake that can be sliced, seasoned, and cooked just like meat. Tempeh is becoming a hamburger alternative for vegetarians. In the West soybeans have been primarily viewed as an oilseed. As early as 1908, some European countries started to import beans from China to process into o i l and meal. Commercial o i l m i l l processing plants, however, were not b u i l t i n the U.S. u n t i l 1922 (1). The o i l was then mostly for i n d u s t r i a l uses. But, because of declining i n d u s t r i a l uses and increasing demand for edible o i l i n the late 1930s, research on soybean o i l for food uses was encouraged. By the seventies, soybean o i l became a major edible o i l i n the United States. Soybean meal, a by-product from the extraction of o i l has been widely used as animal feed since the late 1930s. American soybean processors also produce a v a r i e t y of edible protein products from the meal, such as defatted g r i t s and f l o u r s , concentrates, and isolates. These products became known i n the f i f t i e s and reached the highest popularity as meat extenders i n 1973. Since then t h e i r use has been s t a t i c , although the food industry continues to use these products as ingredients i n many food systems. The use of these edible soy protein products as d i r e c t food, however, i s s t i l l waiting to be accepted. This chapter not subject to U.S. copyright. Published 1986, American Chemical Society

46

PLANT PROTEINS

In East A s i a , on the other hand, soybeans have t r a d i t i o n a l l y been used d i r e c t l y as foods. Centuries of creative s t r i v i n g have yielded great numbers of protein foods that are v e r s a t i l e , e a s i l y digestible and d e l i c i o u s . It has been said that because of the existence of soybeans, the countries of East Asia succeeded i n supporting a high population density i n those distant days. Based on processing technology, the soybean foods that have been consumed i n East Asia may be c l a s s i f i e d into two general types non-fermented and fermented ( 2 - 8 ) as shown i n Table I. Names of these foods and the details of preparing and serving such foods may vary from country to country. Among them, soybean curd (tofu) and soy sauce have been the most widely consumed i n the Orient,

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch005

Table I. Foods Nonfermented Fresh green soybeans

Soybean sprouts Soybean milk P r o t e i n - l i p i d film

Soybean curd

Soybean flour Fermented Soy sauce

Miso

Hamanatto Sufu

Tempeh

Natto

(tofu)

Oriental Soybean Foods

Description and Uses Picked plump, firm, bright green before maturation. Cooked and served as fresh green vegetable. Bright yellow beans with 3 - 5 cm sprouts. Cooked and served as vegetable or i n salad. Water extract of soybeans, resembling dairy milk. Served as breakfast drink. Cream-yellow film formed over the surface of simmering soybean milk. Cooked and used as meat. White or pale yellow curd cubes coagulated from soybean milk. Served as main dish with or without further cooking. Ground roasted dry beans, nutty f l a v o r . Used as f i l l i n g or coating for p a s t r i e s . Dark reddish brown l i q u i d , salty taste suggesting the q u a l i t y of meat extract, a flavoring agent. Paste, smooth or chunky, l i g h t yellow to dark reddish brown, s a l t y and strongly flavored resembling soy sauce, a flavoring agent. Nearly black soft beans, s a l t y flavor resembling soy sauce, a condiment. Cream cheese-type cubes, s a l t y , a condiment, served with or without further cooking. Cooked soft beans bound together by mycelium as a cake, clean fresh and yeasty odor. Cooked and served as main dish or snack. Cooked beans bound together by and covered with viscous, sticky polymère produced by b a c t e r i a , ammonium odor, musty f l a v o r , served with or without further cooking as main dish or snack.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch005

5.

WANG

47

Uses of Soybeans as Foods

According to industry s t a t i s t i c s gathered i n early 1984 by Shurtleff and Aoyagi of the Soyfood Center i n C a l i f o r n i a (9), Americans were consuming an average of 2.22 pounds of such t r a d i t i o n a l soybean foods per year per capita as compared to 1.37 pounds of the modern soy protein foods. The annual production of tofu has increased from 12,020 MT i n 1978 to 24,300 MT i n 1983, with an average annual growth rate of 15% and the highest growth rate of 27% i n 1979. The annual production of tempeh has increased from 511 MT i n 1981 to 900 MT i n 1983, with the average annual growth rate of 33% and the highest growth rate of 36% i n 1982. Soy protein i s o l a t e s , which had the fastest growth rate among the modern soy products, increased from 11,000 MT produced i n 1970 to 41,000 MT i n 1982, with an average annual growth rate of 11%. The production figures on soy isolates also include exports. Consequently, the growth rate of consumption in U.S. would be s i g n i f i c a n t l y lower than the growth rate of production indicated. Furthermore, there has been l i t t l e or no growth i n the combined U.S. production of soy f l o u r , isolates and concentrates since 1974 based on a survey made by Shurtleff and Aoyagi (9). Tofu Tofu has long been a source of protein i n the Orient. It has much the same importance to the people of the Orient that meats, eggs and cheese have for the people i n Western Countries. Tofu is usually sold i n the form of a wet cake with a creamy-white c o l o r , smooth custard-like texture and a bland taste. It i s highly hydrated and, depending on the water content, tofu products with different c h a r a c t e r i s t i c s can be produced. The t y p i c a l o r i e n t a l type of tofu has a water content about 85%. Japanese prefer tofu having a smooth, f r a g i l e texture that contains about 88% water. The Chinese, on the other hand, produce many types of firm products with a chewy meatl i k e texture and a water content as low as 50-60%. Western consumers l i k e tofu with a firm texture; therefore, tofu found i n the U.S. supermarkets contains 75-80% water. Because of i t s fine texture, bland taste and l i g h t c o l o r , tofu has been used i n nearly every culinary context: desserts, salads, breakfast foods, dinner entrees and burgers. It can be cooked simply with desired flavoring agents or i t can be e a s i l y incorporated with other foodstuffs. Preparation. Tofu i s made by coagulating the proteins with a calcium or magnesium s a l t from a hot-water extracted, p r o t e i n - o i l emulsion (soybean milk) of soybeans. The process i s simple (Figure 1), but making a reproducible high-quality product i s a problem. Many factors, from the quality of the dry beans to pressing the curd can affect the y i e l d and q u a l i t y of the resultant tofu. In recent years, several studies (10-14) have been made on tofu processing i n an attempt to better understand the process and to optimize the processing conditions. Three main steps are involved i n making tofu (Figure 1): Preparation of soybean milk, coagulation of p r o t e i n , and formation of tofu cakes i n a mold. By experience, the Orientals have found that the most suitable r a t i o of water (including that absorbed during soaking) to dry soybeans i s 8:1 to 10:1. Watanabe et a l (15)

American Chemical Society Library 1155 16th St., N.W. Washington, O.C.

20036

PLANT PROTEINS

Dry Soybeans Soaked in water 16 hr, 20-22°C. Drained, washed, ground with water. More water added to make ratio

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch005

of water to dry beans 10:1

Soybean mash

(Okara)

Cooled to 75°C Added coagulant (powderd gypsum, Ca, Mg-salts, hydrate, 0.02-U.04M) Curd

(fresh Tofu)

Figure 1.

Flow diagram for preparation of tofu.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch005

5.

WANG

49

Uses of Soybeans as Foods

noted a s i g n i f i c a n t reduction i n the amount of protein and t o t a l solids extracted when the amount of water used was reduced to 6.5 times that of dry beans. Increasing the amount of water over 10:1 increases the extractable materials; however, excess water would result i n a soybean milk too low i n protein to achieve a proper curd formation. Soaking the beans i n water f a c i l i t a t e s the grinding and i t removes some undesirable factors such as the gas-forming o l i g o ­ saccharides, but i t also leaches out soluble proteins. To keep soaking losses at a minimum and to save energy, hydration of soybeans at an ambient temperature, around 2 0 - 2 2 ° C for 16-18 h r , i s most suitable (16). Grinding the soaked beans expedites the extraction and also the formation of the p r o t e i n - l i p i d emulsion. A heat treatment i s e s s e n t i a l , not only for protein denaturation to a t t a i n proper curd formation ( Π ) , but to improve n u t r i t i o n a l value and to reduce o f f - f l a v o r . Based on i n v i t r o d i g e s t i b i l i t y and amino acid composition (13), the maximum n u t r i t i v e value of soybean milk can be ensured by b o i l i n g for 10-15 min. Excessive heat not only adversely affects the n u t r i t i v e value and tofu texture, but also reduces the t o t a l solids recovery, and thus reduces the tofu y i e l d . Coagulation is the most important step i n terms of reproducible y i e l d and texture of tofu, but i t is the least understood. In the Orient, making of tofu has been considered an a r t , and even today, the relationship between the ion binding to the soybean proteins and the coagulation phenomenon are s t i l l not completely understood. According to Fukushiraa (17), native soy protein molecules are unfolded during heating. Consequently, the free SH groups, d i s u l f i d e bonds and hydrophobic groups are exposed. In a d i l u t e s o l u t i o n , the unfolded proteins remain soluble, but as the exposed groups are brought closer together through concentration by drying or freezing, or through n e u t r a l i z a t i o n of molecular charges, i r r e v e r s i b l e aggregates r e s u l t . The bonds responsible for the intermolecular polymerization are the d i s u l f i d e bonds formed by the s u l f h y d r y l / d i s u l f i d e interchange reaction and also the interactions among the hydrophobic amino acid residues. Fukushima (17) postulated that the i r r e v e r s i b l e coagulation i n tofu production i | b r o u g h £ about by decreasing molecular charges, because added Ca or Mg ions bind with the negatively charged a c i d i c amino acid residues and the sulfide group of the unfolded protein molecules. +

+

Recent studies (10,11,13) have shown that both ionic concentration and type of coagulant affect the quantity and q u a l i t y of the resultant tofu. Results obtained from our laboratory are shown i n Figures 2 and 3 (13). When the concentration of the coagulant i s lower than 0.01 M and higher than 0.1 M, there is no curd formation. In studying the binding of unfractionated soybean proteins with calcium i o n , Appurao and Rao (18) observed that at higher calcium concentrations the extent of p r e c i p i t a t i o n decreases and the protein becomee soluble again. Our data are consistent with t h e i r observations. Data i n Figure 2 also show that salt concentrations between 0.02-0.04 M result i n the highest nitrogen recovery and that the s e n s i t i v i t y to the concentration s h i f t s i s the least. Thus, the use of s a l t at a l e v e l between 0.02 to 0.04 M is most l i k e l y to y i e l d a reproducible product with a high nitrogen

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch005

50

PLANT PROTEINS

80 I 0.01

1

1

1

1

1

1

1

0.02

0.03

0.04

0.05

0.06

0.07

0.08

so I 0.01

1

1

1

1

1

1

1

0.02

0.03

0.04

0.05

0.06

0.07

0.08

Concentration of Coagulant (M)

Figure 2. Relationship of concentration and type of coagulant to the y i e l d of tofu (13).

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch005

WANG Uses of Soybeans as Foods 51

52

PLANT PROTEINS

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content. Data on texture c h a r a c t e r i s t i c s (Figure 3) also indicate that there i s l i t t l e s e n s i t i v i t y to concentration changes when a s a l t l e v e l of 0.02-0.04 M i s used. The hardness and the b r i t t l e n e s s of the curds, however, are influenced by the type of s a l t used. Calcium chloride and magnesium chloride result i n curds with much greater hardness and b r i t t l e n e s s than calcium sulfate and magnesium sulfate suggesting that anions have a greater effect on texture than cations. This observation agrees with a study by Aoki (19) on the effect of s a l t on the gelation of soybean proteins, where anions were found to have a stronger effect on water-holding capacity than cations. The hardness of tofu increases as i t s water content decreases (14). Tsai et a l (II) found that coagulant concentrations between 0.025 and 0.03 M are the most suitable for making Chinesestyle tofu. The temperature of the soybean milk at the time coagulants are added, the modes of mixing and pressing greatly affect the y i e l d and texture of the resulting tofu. Increasing the temperature increases the hardness, but decreases the volume, weight, and water content of tofu (13). Increasing mixing also decreases tofu volume and increases hardness (10 13). y

Thus, many factors aftect the f i n a l product. By knowing the effects that each factor produces, one can choose and establish a set of conditions to reproduce the desired type of tofu.

Soybean Variety. Saio and her coworkers (20) speculated that soybean v a r i e t y could have an effect on tofu texture, because they found that a gel made from isolated IIS globulin i s much harder and more e l a s t i c than that made from 7S g l o b u l i n . They also noted increasing tofu hardness as the amount of phytic acid was increased i n soybean milk, but such chemical variations between v a r i e t i e s may not be great enough to have the influence on texture that processing variables do. Recently, Skurray et a l (12) made a study with 15 v a r i e t i e s and found no s i g n i f i c a n t c o r r e l a t i o n between the r a t i o of 7S to 11S protein or phosphorus content and the q u a l i t y of tofu. However, they did find that the q u a l i t y of tofu i s more affected by the amount of calcium ion added. Wang et a l (14) studied v a r i e t a l effects with 5 U.S. and 5 Japanese soybean v a r i e t i e s grown under the same environmental conditions, and found that the composition and color of tofu are affected by soybean v a r i e t y but that y i e l d and texture are not s i g n i f i c a n t l y affected. V a r i e t i e s with a dark brown hilum result i n tofu with a less a t t r a c t i v e color so that these v a r i e t i e s are not desirable. Tofu made from v a r i e t i e s with a high protein content has a higher p r o t e i n / o i l r a t i o than tofu made from v a r i e t i e s with less protein (Table I I ) . Therefore, v a r i e t i e s with high protein are preferred.

5.

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Uses of Soybeans as Foods

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Table I I . Protein to O i l Ratio of Tofu and Soymilk as Affected by Protein and O i l Content of Soybeans (14)

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch005

Soybeans Oil Protein Variety Wase-Kogane Vinton Toyosuzu Coles Yuuzuru Tokachi-Nagaha Weber Hodgson Corsoy Kitamusume

% 45.2 45.1 44.1 43.2 42.3 41.δ 40.9 40*9 40.8 40.8

% 17.4 17.9 18.1 18.5 17.7 17.3 19.3 19.4 18.9 19.4

Soybeans 2.60 2.52 2.44 2.34 2.39 2.42 2.12 2.11 2.16 2.10

Protein/Oil Soymilk 2.49 2.50 2.13 2.11 2.30 2.12 1.75 1.90 1.95 1.86

Tofu 2.07 2.01 1.87 1.78 1.89 1.88 1.57 1.67 1.69 1.57

Dry basis. Composition and N u t r i t i o n a l Value of Tofu. The composition of tofu may vary depending on soybean v a r i e t y used and method of preparation as exemplified i n Tables II and I I I . Since the method of preparation greatly affects the water content of the product, i t influences the percentage of other components (Table I I I ) . Tofu available i n U.S. supermarkets usually contains 80% or less water so that i t may have more than 10% of p r o t e i n . Other nutrients t y p i c a l l y present i n 100 g tofu with 84.8% of water are: f i b e r , 0.1 g; calcium, 128 mg; phosphorus, 126 mg; i r o n , 1.9 mg; sodium 7 mg; potassium, 42 mg; thiamin, 0.06 mg; r i b o f l a v i n , 0.03 mg; n i a c i n , 0.1 mg (21). Tofu has been a source of calcium i n the Oriental d i e t . The calcium content of tofu varies depending on the coagulant used. Tseng et a l (22) reported that tofu prepared with a calcium s a l t has a higher calcium content and higher Ca/P r a t i o than that prepared by other coagulants. They suggested that tofu can help to correct the imbalanced Ca/P r a t i o i n many American d i e t s . A l s o , tofu made from calcium s a l t i s a good source of calcium i n vegetarian d i e t s . Table I I I .

Composition of Tofu as Related to Percentage of Water

Water

Protein

Oil

%

%

%

%

84.8 85.1 (84.2-85.7) 88.0

7.8 7.5 (6.8-8,4) 6.0

4.2 4.2 (3.8-4.7) 3.5

3.2 3.2

Other Solids

2.5

Protein Oil 1.9 1,8 (1.6-2.1) 1.7

Ref. 21 I4 a

17

Average of 10 soybean v a r i e t i e s , with ranges i n parenthesis. Although tofu has been claimed as a low-calorie protein food, the following comparison needs to be considered. One hundred grams of tofu (water, 84.8 g; protein 7.8 g; o i l , 4.2 g) contains about 72 c a l o r i e s , whereas 100 g of cooked hamburger (water, 54.2 g; p r o t e i n , 24.2 g; f a t , 20.3 g) has 286 c a l o r i e s (21). Although the hamburger

54

PLANT PROTEINS

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meat provides more than three times as much protein as tofu, i t has a lower p r o t e i n / f a t r a t i o (1.2 vs 1.9). Accordingly, hamburger has more calories than tofu based on the weight that provides the same amount of protein* Per 50 g p r o t e i n , hamburger has 591 and tofu has 461 c a l o r i e s . Hamburger also has more fat i n such a comparison. However, p r o t e i n / f a t ratio varies greatly among the various cuts and types of meat. Meat that is well trimmed to arrive at a higher p r o t e i n / f a t r a t i o could have less calories and fat content than tofu to provide the same amount of protein. Therefore, tofu can not always be considered as low c a l o r i e food. However, tofu i s a lowdensity protein food, and i s thus more f i l l i n g . The indisputable n u t r i t i o n a l assets of tofu are the absence of cholesterol and lactose, and low amounts of saturated fatty acids. Microbiological Quality of Tofu. Tofu i s a p r o t e i n - r i c h substrate with pH around 6, hence i t i s quite susceptible to microbial growth. T r a d i t i o n a l l y , tofu has been made and consumed i n the same day. However, i n the United States, tofu may be held at the supermarkets for many days on produce counters before consumption where temperatures are usually 10-15°C. Thus, microbial deterioration becomes a serious problem (23-25). Tofu should be r e l a t i v e l y free of vegetative microbial c e l l s i f i t is made under proper sanitary conditions. Cooking the soybean mash at the b o i l i n g temperature for 15 rain should k i l l a l l vegetative c e l l s and leave only the heat-resistant spores as survivors. However, the presence of heat-resistant, spore-forming bacteria observed on soybeans (unpublished data) suggests that, even though contamination may have been prevented during processing, b a c t e r i a l growth could occur i f tofu i s stored under conditions suitable for the microbes to grow. Measures then must be taken to prevent the growth of these microorganisms i n order to improve the microbiological quality of tofu. In addition to proper storage conditions, the processors should throughly clean the beans to reduce the surface microbial load and carry out the processing with a high l e v e l of sanitary practices (25,26). Recently, studies to evaluate the microbiological safety of tofu were made by Kovats et a l (27). Water-packed tofu samples were inoculated with such common food pathogens as Clostridium botulinum, Staphylococcus aureus, Salmonella typhimurium, and Yersinia e n t e r o c o l i t i c a , then held at different temperatures for various lengths of time. They found that a l l four organisms grew i n waterpacked tofu. C. botulinum toxin was produced i n tofu held at 15° and 25°C within 3 days and 1 wk, respectively, but not at 5 ° and 10°C within 6 wk. S. aureus and S. typhimurium grew at similar rates at 10, 15, 25°C., but neither pathogen grew during storage at 5°C. Staphylococcal enterotoxin was not produced within 4 wk at 10°C even though a population of greater than 10 /g was present i n most samples analyzed. Y. e n t e r o c o l i t i c a grew at a l l temperatures evaluated (5, 10, 15 and 25°CT! Isolates recovered from tofu samples agglutinated with antiserum (WA-SAA), indicating that the isolates continued to express their virulence-associated determinant after growing i n tofu. Thus, l i k e many other foods, the potential of microbial hazards i s great for tofu produced under unsanitary conditions and/or stored at improper temperatures. High l e v e l 7

5.

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Uses of Soybeans as Foods

55

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch005

sanitary p r a c t i c e s , pasteurization after packaging> and storage and display at 5°C or less by manufacturers, d i s t r i b u t o r s and r e t a i l e r s were recommended by Ko vat s et a l (27). Tofu can be kept frozen or freeze-dried to prevent microbial deterioration. However i n t e m o l e c u l a r interactions occur during frozen storage. As a r e s u l t , the texture of tofu i s changed from s o f t , smooth to sponge-like with a meat-like chewiness. Tempeh Tempeh, o r i g i n a t i n g i n Indonesia, i s made by fermenting dehulled and b r i e f l y cooked soybeans with Rhizopus mold; the mycelium binds the soybean cotyledons together i n a firm cake. Freshly fermented tempeh has a clean, yeasty odor. When s l i c e d and deep-fat f r i e d , i t has a nutty flavor and pleasant aroma. Tempeh i s used as a main dish and meat substitute i n Indonesia. Vegetarians i n the West have used tempeh as hamburger p a t t i e s . Unlike most other fermented soybean foods which usually involve more than one microorganism, long b r i n i n g , and an aging process, tempeh fermentation i s short and simple and requires only one mold. Preparation. T r a d i t i o n a l l y , soaked, hand-dehulled and b r i e f l y boiled soybeans are inoculated with small pieces of tempeh from a previous fermentation, wrapped i n banana leaves which also serve as a source of inoculum, then l e f t at room temperature for 1-2 days. Studies carried out by Hesseltine et a l (28) resulted i n a pure culture fermentation as shown i n Figure 4. To save time and labor, mechanically dehulled, f u l l - f a t g r i t s have replaced the t r a d i t i o n a l whole soybeans. A tempeh s t a r t e r containing spores of Rhizopus oligosporus NRRL 2710 (29) i s now used i n the West i n place of t r a d i t i o n a l inocula. Not only are P e t r i dishes the most convenient laboratory container, they also are used commercially i n preparing tempeh p a t t i e s . Other containers such as shallow aluminum f o i l or metal trays with perforated bottoms and perforated p l a s t i c f i l m covers, and perforated p l a s t i c bags and tubings have been used successfully for tempeh fermentation. Rhizopus oligosporus requires a i r to grow, but too much aeration w i l l cause spore formation and also may dry up the beans, r e s u l t i n g i n poor mold growth. Therefore, both properly perforating the containers and packing the beans for fermentation are important. Tempeh Products from Grains and Other Beans. T r a d i t i o n a l l y tempeh is made from soybeans known as tempeh kedele. However, copra (pressed coconut cake) and the by-product from making soybean milk have also been used i n Indonesia to make tempeh known as tempeh bongkrek and tempeh gembus, respectively. Recently, attempts have been made (30) to make tempeh-like products from grains such as wheat, oats, b a r l e y , r i c e , mixtures of cereal and soybeans, and from beans other than soybeans, such as broad beans, cowpeas, mung beans and winged beans. In the United States, tempeh made from a mixture of wheat and soybeans (31) has been available commercially since 1970. Biochemical Changes During Fermentation. The effects of R. oligosporus on soybeans have been studied by several investigators (30,32). As shown i n Table IV, the fermentation process does not

PLANT PROTEINS

56

Dehulled full-fat soybean grits {

•-Tap

water

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch005

Soaked 30 min. at 25 C

Drained }

-*-Tap

water

Cooked (30 min.)

• Drained and cooled

• Inoculated

* - Spore suspension of

ι

Rhizopus

t

oligosporus

SaitO

NRRL 2710

Tightly packed in petri dishes

Incubated 31 C for 20-24 hr

•

Tempeh cake

Figure 4. Flow diagram for tempeh fermentation.

5.

Uses of Soybeans as Foods

WANG

57

greatly affect the proximate composition of soybeans. The s l i g h t increase i n the percentage of protein reflects the decrease of other constituents that the mold might have consumed for growth. Table IV. Food Soybeans Tempeh

5

Proximate Composition of Soybeans and Tempeh Carbohydrates

Protein

Oil

Fiber

Ash

%

%

%

%

%

26.8 24.7

3.9 3.1

3.4 3.3

18.1 20.8

47.8 48.1

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch005

Treated s i m i l a r l y as for fermentation except the inoculation step was omitted. As the mold begins to grow r a p i d l y , the temperature of fermenting beans rises a few degrees above the incubator temperature, then f a l l s as the growth of mold subsides. The pH increases steadily to above 7, presumably because of protein break-down. After 69 hrs. of incubation, soluble solids r i s e from 13 to 28%, soluble nitrogen increases from 0.5 to 2.0%, but t o t a l nitrogen remains f a i r l y constant and reducing substances decrease s l i g h t l y , probably due to u t i l i z a t i o n by the mold. The mold does not u t i l i z e the carbohydrates i n the soybeans; instead, i t uses the soybean o i l as i t s energy source. Although t o t a l nitrogen remains f a i r l y constant during fermentation, free amino acids increase i n tempeh. The essential amino acid index, on the other hand, is not s i g n i f i c a n t l y changed by fermentation. Perhaps the amount of mycelial protein present i n tempeh i s not high enough to a l t e r greatly the amino acid composition of the soybeans, nor does the mold depend upon any s p e c i f i c amino acid for growth. N i a c i n , r i b o f l a v i n , pantothenic acid and vitamin B contents are greatly increased i n tempeh during fermentation, whereas thiamin exhibits no s i g n i f i c a n t change. R. oligosporus appears to have a great synthetic capacity for n i a c i n , r i b o f l a v i n , pantothenic a c i d , and vitamin B$, but not for thiamin. The most interesting and important finding was the presence of vitamin B12 i n tempeh because foods derived from plant materials are deficient i n this essential nutrient. Vitamin B i s known to be synthesized by microorganisms; however, molds have not been reported to produce Vitamin B . Liem et a l (33) found a f a i r l y high amount of vitamin B i n commercial tempeh bought from Canada and subsequently confirmed that the major source of the vitamin was a result of a contaminating bacterium which the authors isolated and i d e n t i f i e d as K l e b s i e l l a . They reported that tempeh made from pure mold isolated from commercial tempeh contained n u t r i t i o n a l l y i n s i g n i f i c a n t amounts of vitamin B , confirming that the tempeh mold does not produce the vitamin. On the other hand, tempeh made with the mold and the bacterium, K l e b s i e l l a , isolated from commercial tempeh, had 150 ng of vitamin B per gram of tempeh. The presence of the mold does not interfere with the production of vitamin B i by the b a c t e r i a , but presence of the bacteria requires longer fermentation time. Liem and his co-workers also demonstrated that soaking soybeans either with or without an acid did not increase the vitamin B content. The results indicated that tempeh made with 6

1 2

1 2

1 2

1 2

1 2

2

1 2

PLANT PROTEINS

58

pure mold fermentation under hygienic conditions adopted for food processing i n this country has no n u t r i t i o n a l l y s i g n i f i c a n t amount of vitamin B . However, there i s a great potential to make vitamin B - e n r i c h e d tempeh with an inoculum containing R. oligosporus and a vitamin B 2""P °ducing bacterium. 1 2

12

r

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch005

1

N u t r i t i o n a l Value. Although enzymes produced by the mold have acted upon the substrate and p a r t l y hydrolyzed i t s constituents into small molecules, the d i g e s t i b i l i t y coefficient of tempeh tested by the rat-assay method i s not s i g n i f i c a n t l y different from that of unfermented substrate. It i s also not surprising to learn that the protein efficiency r a t i o (PER) of tempeh (8) as determined by rat assay i s not s i g n i f i c a n t l y different from that of unfermented but properly heat-treated soybeans, because the fermentation process does not s i g n f i c a n t l y change the t o t a l nitrogen and the amino acid composition. However, tempeh made from a mixture of wheat and soybeans has been shown (8) to have a better protein value than that made from soybeans alone, because of the complementary effect of mixed proteins and the increased a v a i l a b i l i t y of lysine i n wheat from fermentation. Increase i n vitamins, such as n i a c i n , r i b o f l a v i n , pantothenic a c i d , Vitamin Be, and Vitamin B i s of great n u t r i t i o n a l significance, especially where f o r t i f y i n g foods with synthetic vitamins i s not practiced. 1 2 )

Microbiological Quality of Tempeh. Like tofu, tempeh should normally be r e l a t i v e l y free of contaminated vegetative c e l l s , but may not be free of heat-resistant spores. F a i l u r e of fermentation caused by b a c t e r i a l contamination has been reported by tempeh producers. In order to assure successful fermentation, a starter with high v i a b i l i t y is as important as a high l e v e l of sanitary p r a c t i c e s . To maintain the microbiological quality of tempeh, steaming after fermentation and then freezing are recommended. Results obtained from studies on the safety of tempeh inoculated with different b a c t e r i a l pathogens (34) indicated that tempeh should be steamed after fermentation and then kept at 5°C or below u n t i l i t i s used. Conclusions Whole soybean foods have been the major source of protein i n East Asia since ancient times and various methods have been developed to make soybeans more palatable. Among these simply made soybean foods, tofu and tempeh have recently become increasingly popular i n the West. The production processes may not improve the n u t r i t i o n a l value of soybean p r o t e i n , but they reduce the cooking time, improve the organoleptic characteristics and increase the v e r s a t i l i t y of soybean uses. With the recently increasing interest i n protein foods other than those from animal o r i g i n , the consumption of tofu and tempeh has been on an upsurge i n the West and i s expected to continue i t s steady growth i n the years to come.

5.

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Uses of Soybeans as Foods

59

Literature Cited 1. 2. 3.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch005

4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.

16. 17. 18. 19. 20. 21. 22. 23. 24. 25.

Smith, A. K.; Circle, S. J. Eds. In "Soybeans: Chemistry and Technology"; AVI: Westport, Conn., 1972; Chap. 1. Hesseltine, C. W.; Wang, H. L. In "Soybeans: Chemistry and Technology"; Smith, A. K.; Circle, S. J., Eds.; AVI: Westport, Conn., 1972; Chap 11. Wang, H. L.; Mustakas, G. C.; Wolf, W. J.; Wang, L. C.; Hesseltine, C. W.; Bagley, Ε. B. "Soybeans as Human Food: Unprocessed and Simply Processed," U.S. Department of Agriculture, Utilization Res. Rep. No. 5, January, 1979. Fukushima, D. J. Am. Oil Chem. Soc. 1979, 56(3), 357. Winarno, F. G. J. Am. Oil Chem. Soc. 1979, 56(3), 363. Wang, H. L.; Hesseltine, C. W. In "Microbial Technology'; Peppler, H. J.; Perlman, D., Eds.; Academic Press: New York, 1979; Vol II, Chap. 4. Fukushima, D. "Proc. World Conference on Soya Processing and Utilization," J. Am. Oil Chem. Soc. 1981, 58, 346. Wang, H. L. In "Handbook of Processing and Utilization of Agriculture," Wolff, I. Α., Ed.; CRC Press, Boca Raton, Florida, 1983; Vol. II, Part 2, p. 91. Shurtleff, W.; Aoyagi, A. "The Soyfoods Industry and Market: Director and Databook." The Soyfoods Center, Lafayette, CA. 1984-1985. Saio, K. Cereal Foods World 1979, 24, 342. Tsai, S. J.; Lau, C. T.; Kao, C. S.; Chen, S. C. J. Food Sci. 1981, 46, 1734. Skurray, G.; Cunich, J.; Carter, O. Food Chem. 1980, 6, 89. Wang, H. L.; Hesseltine, C. W. Process Biochem. 1982, 17, 7. Wang, H. L.; Swain, E. W.; Kwolek, W. F.; Fehr, W. R. Cereal Chem. 1983, 60, 185. Watanabe, T.; Fukamachi, C.; Nakayama, O.; Teramachi, Y.; Abe, K.; Suruga, S.; Mivanage, S. The Report of Food Research Institute, Ministry of Agriculture and Forestry, Japan, 1960, 1413 (in Japanese). Wang, H. L.; Swain, E, W.; Hesseltine, C. W.; Heath, H. D. J. Food Sci. 1979, 44, 1510. Fukushima, D. In "Chemical Deterioration of Proteins"; Whitaker, J. R.; Fugimaki, Μ., Eds.; ACS SYMPOSIUM SERIES No. 123, American Chemical Society: Washington, D.C., 1980, p. 211. Appurao, A. G.; Rao, M. S. Cereal Chem. 1975, 52, 21. Aoki, H. Nippon Hogli Kagaku Kaishi 1965, 39, 277. Saio, K.; Kamiya, M.; Watanabe, T. Agri. Biol. Chem. 1969, 33, 1301. "Composition of Foods," Agriculture Handbook No. 8, U.S. Department of Agriculture, 1975. Tseng, R. Y. L.; Smith-Nury, E.; Chang, Y. S. Home Economics Res. J. 1977, 6, 171. Hankin, L.; Hanna, J. G. Bulletin 810, The Connecticut Agriculture Experimentation Station, New Haven, Connecticut. 1983, March. Aulisio, C. C. G.; Stanfield, J. T.; Weagant, S. D.; H i l l , W. E. J. Food Protect. 1983, 3, 226. Rehberger, T. G.; Wilson, L. Α.; Glatz, B. A. J. Food Protect. 1984, 3, 177.

60

26. 27. 28. 29. 30. 31. 32.

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33. 34.

P L A N T PROTEINS

Wang, H. L. J. Am. Oil Chem. Soc. 1983, 61, 528. Kovats, S. K.; Doyle, M. P.; Tanaka, N. J. Food Protect. 1984, 47, 618. Hesseltine, C. W.; Smith, M.; Bradle, B.; Ko Swan Djien. Dev. Ind. Microbiol. 1963, 4, 275. Wang, H. L.; Swain, E. W.; Hesseltine, C. W. J. Food Sci. 1975, 40, 168. Steinkraus, Κ. Η., Ed, Handbook of Indigenous Fermented Foods, Marcel Dekker, New York, 1983. Hesseltine, C. W.; Smith, B.; Wang, H. L. Development in Industrial Microbiology 1967, 8, 179. Wang, H. L.; Hesseltine, C. W. In "Microbial Technology"; Peppler, H. J.; Perlman, D., Eds.; Academic Press: New York, 1979; Vol. II, p. 95. Liem, I. T. H.; Steinkraus, K. H.; Cronk, T. C. Appl. Environ. Microbiol. 1977, 34, 773. Tanaka, N.; Kovats, S. K.; Guggisberg, J. Α.; Meske, L. M.; Doyle, M. P. J. Food Protect. 1985, 48, 438.

RECEIVED December 13, 1985

6 Incorporation of Cottonseed into Foods for Humans Elwood F. Reber

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch006

Department of Nutrition and Food Sciences, Texas Woman's University, Denton, TX 76204

The Food and Drug Administration approved the use of cottonseed containing not more than 450 ppm gossypol for human use. Glandless whole kernel cottonseed flakes and cot-n-nuts are commercially available. Studies incorporating cottonseed into many different foods have yielded acceptable products with improved protein quantity and quality. The presence of free gossypol and cyclopropenoid fatty acids (CPFA) potentially limits the use of cottonseed in human foods. The levels of free gossypol and CPFA are reduced in processing the seed and preparation of food. The amount of free gossypol and CPFA in the food as eaten should be determined. The American Oil Chemists' Society method for free and total gossypol is not specific for gossypol and gave false positive readings for several food ingredients. Glandless cottonseed i s a valuable addition to the food supply in the United States. The development and utilization of glandless cottonseed in the rest of the world would be a major contribution to the alleviation of severe hunger in some areas. Glanded c o t t o n s e e d i s t h e c o t t o n c r o p grown around t h e w o r l d . The c o t t o n p l a n t and t h e c o t t o n s e e d have pigment g l a n d s which c o n t a i n s e v e r a l pigments t h a t c a n make t h e seed appear dark green t o b l a c k . One o f t h e pigments i s g o s s y p o l . C o t t o n s e e d was f i r s t s u g g e s t e d as a f o o d s o u r c e f o r human consumption i n 1876 (1). When g l a n d e d c o t tonseed i s f e d t o monogastric animals, t h e oxygen-carrying c a p a c i t y of t h e b l o o d i s reduced and s h o r t n e s s o f b r e a t h , edema o f t h e l u n g s and p a r a l y s i s may o c c u r . Rats u s u a l l y show s i g n s o f l o s s o f a p p e t i t e , d e c r e a s e d growth, rough h a i r c o a t and l i s t l e s s n e s s (2). However, t h e t o x i c e f f e c t s o f g o s s y p o l a f f e c t s v a r i o u s a n i m a l s t o d i f f e r e n t degrees o f s e v e r i t y . The C h i n e s e (3) found t h e consumption of u n r e f i n e d c o t t o n o i l by humans caused a r e v e r s i b l e i n f e r t i l i t y i n males. C o t t o n s e e d f l o u r h a s been i n c l u d e d i n INCAPARINA baby f o o d f o r m u l a s i n Guatemala (4).

0097-6156/86/0312-0061 $06.00/0 © 1986 American Chemical Society

62

PLANT PROTEINS

Glanded c o t t o n s e e d has been used t o produce a d e f a t t e d c o t t o n seed f l o u r w i t h r e d u c e d g o s s y p o l c o n t e n t by a p r o c e d u r e known as t h e l i q u i d c y c l o n e p r o c e s s (LCP). LCP c o t t o n s e e d f l o u r has been used i n the p r e p a r a t i o n o f many foods t h a t have been t e s t e d i n s e v e r a l a n i m a l and human n u t r i t i o n s t u d i e s . The commercial p r o d u c t i o n o f LCP c o t t o n s e e d f l o u r has n o t been s u c c e s s f u l (.5) .

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch006

S t u d i e s w i t h Raw, Cooked and Roasted

Cottonseed

G l a n d l e s s c o t t o n s e e d i s o b t a i n e d from a c o t t o n v a r i e t y t h a t has reduced amounts o f pigment and g o s s y p o l i n t h e seed k e r n e l . The f i r s t r e p o r t o f a sub-acute t o x i c i t y i n v e s t i g a t i o n o f g l a n d l e s s c o t tonseed f e d t o r a t s was made by Reber and Pyke ( 6 ) . The i n v e s t i g a t i o n was d e s i g n e d t o s a t i s f y t h e r e q u i r e m e n t s o f t h e Food and Drug A d m i n i s t r a t i o n (FDA). The r e s u l t s were s u b m i t t e d t o t h e FDA, who o b j e c t e d t o t h e v a l i d i t y o f t h e s t u d y on t h e b a s i s t h a t c o t t o n s e e d o i l was a d e r i v e d component o f c o t t o n s e e d k e r n e l s ; so t h e c o n t r o l d i e t d i d not serve i t s purpose. The FDA s u g g e s t e d t h a t a n o t h e r s t u d y be conducted where t h e r a t s would be f e d a c o n t r o l d i e t c o n t a i n i n g 6% c o r n o i l t o be a b l e t o c o n c l u d e w i t h o u t r e s e r v a t i o n t h a t g l a n d l e s s c o t t o n s e e d k e r n e l s a r e s a f e f o r human consumption, based on r a t studies. A p r o t o c o l approved by t h e FDA t o d e t e r m i n e t h e s a f e t y o f low g o s s y p o l c o t t o n s e e d k e r n e l s f o r human consumption was t h e b a s i s f o r the second s t u d y by Reber C7 ) . To p r e p a r e raw c o t t o n s e e d f l o u r , raw k e r n e l s were ground t o meet Ro-tap s i e v e s p e c i f i c a t i o n s o f l a b chow. To p r e p a r e r o a s t e d c o t t o n s e e d f l o u r , raw k e r n e l s were d r y r o a s t e d a t not l e s s than 121°C f o r n o t l e s s t h a n 5 min. To p r e p a r e cooked c o t t o n s e e d f l o u r , raw k e r n e l s were cooked i n steam u n t i l b a t c h temperat u r e had been a t o r above 121°C f o r 5 min. A l l c o t t o n s e e d k e r n e l s were ground i n t h e manner d e s c r i b e d above. The k e r n e l s c o n t a i n e d n o t more than O.037% (370 ppm) o f f r e e g o s s y p o l . They were f r e e o f S a l m o n e l l a and d i d n o t c o n t a i n d e t e c t a b l e amounts o f a f l a t o x i n . The proximate a n a l y s e s o f t h e c o t t o n s e e d f l o u r s a r e shown i n T a b l e I . The g l a n d l e s s c o t t o n s e e d was o b t a i n e d from Rogers C o t t o n s e e d Co., Waco, Texas, t h e n p r o c e s s e d and a n a l y z e d by t h e Food P r o t e i n R e s e a r c h and Development C e n t e r , Texas A&M U n i v e r s i t y , C o l l e g e S t a t i o n , Texas. Table I.

Moisture, % Protein, % Oil, % Ash, % Crude F i b e r , % Gossypol (free) % Gossypol ( t o t a l ) % Lead, ppm A r s e n i c , ppm Heavy m e t a l s , ppm

A n a l y s i s of Cottonseed Raw 6.20 39.13 35.45 4.30 1.48 O.037 O.042 1.5 O.1 10.0

Flours

Roasted 2.27 40.56 37.34 4.44 1.42 O.03 1.5 O.1 10.0

R e p r i n t e d from J . Food S c i . 1981. 46(2):593-596. I n s t i t u t e o f Food T e c h n o l o g i s t s .

C o p y r i g h t by

Cooked 4.23 39.81 36.94 4.39 1.37 O.034 O.034 1.5 O.1 10.0

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch006

6.

REBER

Incorporation of Cottonseed into Foods

63

Growing female r a t s u t i l i z e d cooked o r r o a s t e d c o t t o n s e e d more e f f i c i e n t l y than raw c o t t o n s e e d o r c o n t r o l d i e t . The p e r c e n t a g e s of pups a l i v e a t b i r t h s u r v i v i n g t o 4 days were s i g n i f i c a n t l y h i g h e r f o r r a t s f e d raw o r cooked c o t t o n s e e d than r o a s t e d c o t t o n s e e d . There were no s i g n i f i c a n t d i f f e r e n c e s due t o d i e t o b s e r v e d i n average body w e i g h t s of dams a t p a r t u r i t i o n and a t weaning time o r i n weight o f offspring. There were no d e t r i m e n t a l e f f e c t s due t o f e e d i n g low g o s s y p o l (370 mg/kg) c o t t o n s e e d k e r n e l s a t a l e v e l of 20% o f the d i e t e q u i v a l e n t t o 74 mg o f f r e e g o s s y p o l per kg o f d i e t as e a t e n . Rats f e d c o t t o n s e e d grew as w e l l as o r b e t t e r t h a n c o n t r o l a n i m a l s . Heat treatment o f c o t t o n s e e d a p p a r e n t l y made one o r more n u t r i e n t s more a v a i l a b l e on a n u t r i t i o n a l b a s i s t o female r a t s . O v e r a l l the d i e t c o n t a i n i n g cooked c o t t o n s e e d appeared t o be a b e t t e r d i e t than the d i e t containing roasted cottonseed. These o b s e r v a t i o n s l e d t o an i n v e s t i g a t i o n of the p r o t e i n q u a l i t y o f the c o t t o n s e e d as a f f e c t e d by the p r o c e s s i n g . The same shipment of raw, cooked and r o a s t e d g l a n d l e s s whole k e r n e l c o t t o n s e e d f l o u r s used i n t h e FDA study was used t o determine the p r o t e i n e f f i c i e n c y r a t i o (PER) of each f l o u r ( 8 ) . The a d j u s t e d PER ( T a b l e I I ) o f cooked (2.10) c o t t o n s e e d was s i g n i f i c a n t l y h i g h e r than r o a s t e d (1.77) c o t t o n s e e d . Protein retention efficiency (PRE) f o r r o a s t e d c o t t o n s e e d (58.08) was lower than v a l u e s f o r raw (60.54) and cooked (62.95) c o t t o n s e e d . R e l a t i v e p r o t e i n v a l u e s (RPV) i n d i c a t e d a u t i l i z a t i o n of 91, 91 and 96% o f the p r o t e i n i n raw, r o a s t e d and cooked c o t t o n s e e d , r e s p e c t i v e l y . The m u l t i p l i c a t i o n o f the (RPV) p e r c e n t a g e u t i l i z a t i o n and the p r o t e i n c o n t e n t o f the c o t t o n seed ( T a b l e I) r e s u l t s i n t h e r e l a t i v e u t i l i z a b l e p r o t e i n v a l u e s (Table I I ) . T a b l e I I . Average P r o t e i n E f f i c i e n c y R a t i o (PER), R e l a t i v e P r o t e i n V a l u e (RPV) and R e l a t i v e U t i l i z a b l e P r o t e i n f o r Raw, Roasted and Cooked Whole K e r n e l C o t t o n s e e d 3

Parameter (adjusted)

PER RPV Relative Utilizable Protein^ a

Casein 2.50b

R e p r i n t e d from J . Food Q u a l i t y 1983.

Raw 1.93 O.91 35.61

c

Cottonseed Roasted 1.77ce O.91 36.90

Cooked 2.10CÛ O.96 38.21

6:65-71.

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*ains Corn m e a l , whole F l o u r , w h i t e , wheat F l o u r , w h i t e , wheat w i t h O.3% L - L y s i n e HCI Wheat g l u t e n R i c e , whole Wheat, whole g r a i n s

Legumes and O i l s e e d s Beans, average Peas, d r i e d Peanuts, s h e l l e d Soybean f l o u r , low f a t Soybeans, extruded Sesame seed S u n f l o w e r seed Cottonseed meal or deglanded f l o u r

Food Source

Table I c o n t i n u e d .

9 .2 11 .8 11 .8 80 .0 7 .5 12 .2

14..08 14,.30 15.,84 48..62 19..80 7.,26

42 .3

26..6

59.0 37.0 70.2 65.2

51.1 45.6

52.7

38.4 46.7 42.7 61.4 58.0 53.4 58.1

% 21 .4 24 .0 26 .9 44 .7 52 .5 33 .4 23 .0

%

Crude Protein Content

P r i c e of Source Material .05) according to Duncan's multiple range t e s t .

From (6). Basic values based on 36 observations; Values f o r composition of cooking j u i c e s based on 12 observations because data from 3 patties were pooled in each instance. Means within a column having the same l e t t e r or l e t t e r s are not s i g n i f i c a n t l y d i f f e r e n t (P>.05) according to the Duncan's multiple range t e s t . Three of each type of patty were cooked at 121°C f o r 8, 9, 10, 11 min.; 149°C f o r 5, 6, 7, 8 min.; 177°C f o r 4, 5, 6, 7 min.

z

x

All-beef Textured soy 20% Soy concentrate 20% Soy i s o l a t e 20%

Study I i z

Study i x All-beef Textured soy 20% Textured soy 30% Soy concentrate 20% Soy concentrate 30%

Product

Internal temperature (°C)

Table IV. Cooking C h a r a c t e r i s t i c s of Beef-Soy P a t t i e s

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch007

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch007

7.

KOTULA AND BERRY

Soy Proteins in Meat Products

e f f e c t of s u b s t i t u t i n g soy p r o t e i n f o r muscle and c o n n e c t i v e t i s s u e are p r o b a b l y r e s p o n s i b l e f o r these tenderness improvements as w e l l as t h e f a c t t h a t s o l u b l e p r o t e i n s add t o b i n d i n g p r o p e r t i e s d u r i n g the d e n a t u r i n g of p r o t e i n s a s s o c i a t e d w i t h c o o k i n g . Toasted soy f l o u r , soy g r i t s and c e r t a i n soy p r o t e i n c o n c e n t r a t e s are a l r e a d y denatured p r i o r t o t h e i r a d d i t i o n to meat. An e v a l u a t i o n o f t h e c o m p o s i t i o n of t h e cooking j u i c e s , as presented i n T a b l e IV, demonstrates, by d i f f e r e n c e , t h a t f a t i s r e t a i n e d t o a g r e a t e r e x t e n t by t h e soy c o n c e n t r a t e meat product than by the soy f l o u r meat product or the ground b e e f . The meat product c o n t a i n i n g soy f l o u r l o s t more f a t d u r i n g cooking than d i d the a l l - b e e f ( T a b l e I V ) . S i m i l a r r e s u l t s were r e p o r t e d by Anderson and L i n d (9). When soy p r o t e i n c o n c e n t r a t e s are used i n canned meat products l i k e c h i l i , t h e f a t i s l a n d s w i t h i n t h e chopped meat p r o d u c t s and t h e f a t cap are e l i m i n a t e d ( 1 0 ) . When 4% soy c o n c e n t r a t e was added to a minced pork p r o d u c t , cook out o f f a t and m o i s t u r e was reduced 31% f o r p a s t e u r i z e d product and 34% f o r s t e r i l i z e d product. The s t a b i l i t y o f e m u l s i f i e d products c o n t a i n i n g soy p r o t e i n f l o u r , c o n c e n t r a t e or i s o l a t e was b e t t e r than s i m i l a r emulsions w i t h o u t soy (JJ_) · Emulsion s t a b i l i t y was h i g h e r i n emulsions c o n t a i n i n g soy f l o u r than i n those c o n t a i n i n g soy c o n c e n t r a t e o r isolate. The use o f soy p r o t e i n i s o l a t e has been recommended f o r n o n - s t a n d a r d i z e d sausage type p r o d u c t s because i t binds f a t and water, provides cohesiveness, prevents f a t migration during or a f t e r c o o k i n g , adds p r o t e i n and forms a f i r m g e l s t r u c t u r e 02). In t h e study by Thompson, et a l . ( 1 1 ) , t h e ml of gel r e l e a s e d per 100 g emulsion f o r t h e r e f e r e n c e emûTsion w i t h o u t s o y , w i t h soy i s o l a t e ( S I F ) , soy c o n c e n t r a t e (SCF) or soy f l o u r (SF) was 6 . 0 7 , 5.83, 5.49 and 3 . 0 8 , r e s p e c t i v e l y , when t h e h y d r a t i o n r a t i o s were 1:4 ( f l o u r : w a t e r ) f o r S I F , 1:3 f o r SCF and 1:2 f o r SF. The ml g e l r e l e a s e d per 100 g emulsion c o n t a i n i n g 10, 15, 2 0 , and 25% soy p r o t e i n was 6 . 7 0 , 5 . 0 1 , 3.94 and 3 . 5 7 , r e s p e c t i v e l y . When soy p r o t e i n c o n c e n t r a t e was i n c o r p o r a t e d i n t o an emulsion at t h e 3.5% l e v e l , t h e p r o c e s s i n g y i e l d s , t e x t u r a l p r o f i l e and s e n s o r y t e x t u r a l a t t r i b u t e s of f r a n k f u r t e r s were not d i f f e r e n t among t h e products w i t h and w i t h o u t added soy c o n c e n t r a t e ( 13). An o b j e c t i v e measure of compression and shear modulus i n d i c a t e d t h a t soy p r o t e i n c o n c e n t r a t e i n c o r p o r a t e d i n t o f r a n k f u r t e r s at t h e 3.5% l e v e l had no e f f e c t on b a t t e r s t r e n g t h or t e x t u r e (_U). The a d d i t i o n of a c o t t o n s e e d p r o t e i n t o f r a n k f u r t e r s t o r e p l a c e 5, 10 o r 15% o f the meat r e s u l t e d i n higher pH, l e s s cured c o l o r , l e s s f i r m n e s s o f s k i n , s o f t e r t e x t u r e and reduced d e s i r a b i l i t y as judged by a s e n s o r y panel ( J 5 ) . When s t r u c t u r e d soy p r o t e i n f i b e r was added t o fermented salami at 15 o r 30% l e v e l s , t r a i n e d s e n s o r y panels found t h e f l a v o r to be u n d e s i r a b l e , whereas a 116-member u n t r a i n e d panel found t h e product c o n t a i n i n g 30% soy f l o u r t o be u n d e s i r a b l e i n f l a v o r , tenderness and o v e r a l l d e s i r a b i l i t y (J6»). The f l a v o r o f beef p a t t i e s c o n t a i n i n g 20% soy p r o t e i n f l o u r or c o n c e n t r a t e was r a t e d about equal t o a l l beef p a t t i e s by a 52-member p a n e l , whereas p a t t i e s c o n t a i n i n g 30% were scored lower by the panel ( 6 ) . B e r r y e t a l . (7) found t h e c h a r a c t e r i s t i c " s o y - l i k e " f l a v o r t o be more

81

82

PLANT PROTEINS

p r e v a l e n t i n p a t t i e s made w i t h soy f l o u r vs soy i s o l a t e and soy c o n c e n t r a t e . Compared to a l l - b e e f p a t t i e s , use of soy f l o u r reduced t h e i n c i d e n c e of r a n c i d f l a v o r , which was p r o b a b l y due i n p a r t to the a n t i o x i d a n t p r o p e r t i e s i n h e r e n t to soy f l o u r . F o r t i f i c a t i o n o f the soy f l o u r w i t h i r o n and z i n c e l e v a t e d t h e incidence of rancid f l a v o r .

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch007

Nutritional

Characteristics

T y p i c a l chemical analyses f o r soy f l o u r and soy c o n c e n t r a t e are presented i n T a b l e V. N u t r i t i o n a l l y , soy p r o t e i n s are a good source of amino a c i d s , but they c o u l d b e n e f i t from i n c r e a s e d l e v e l s of m e t h i o n i n e ( 1 8 ) . Though such p r e v i o u s l i t e r a t u r e r e p o r t e d soy p r o t e i n s t o be ïïëficient i n m e t h i o n i n e , t h e r e p o r t o f t h e 1981 Expert Committee on P r o t e i n - E n e r g y Requirements, F o r e i g n A g r i c u l t u r e O r g a n i z a t i o n o f the U n i t e d N a t i o n s , which i s i n p r e s s , i n d i c a t e d soy p r o t e i n products meet the requirements f o r t o t a l s u l f u r amino a c i d s f o r a l l age groups except i n f a n t s . Regardless, m e t h i o n i n e i s an e s s e n t i a l amino a c i d and p r o t e i n q u a l i t y of soy p r o d u c t s w i l l be enhanced by i n c r e a s e d l e v e l s o f t h a t amino a c i d . When Vemury et a l . (19) s t u d i e d the c o m p a r a t i v e v a l u e of s e v e r a l v e g e t a b l e p r o t e i n prôïïucts f e d at equal n i t r o g e n l e v e l s t o human a d u l t s , they r e p o r t e d the products c o n t a i n i n g the h i g h e s t to t h e lowest p r o t e i n n u t r i t i o n a l v a l u e s were egg, b e e f , blended wheat p r o t e i n p r o d u c t , extruded soy f l o u r and extruded soy c o n c e n t r a t e . The authors a l s o r e c o g n i z e d t h a t t h e i r use o f a n i t r o g e n c o n v e r s i o n f a c t o r o f 6.25% r a t h e r than 5.71% f o r soy p r o t e i n r e s u l t e d i n a comparison being made between 22.8 g of p r o t e i n from soy p r o t e i n w i t h 25 g p r o t e i n from b e e f . The blood c h o l e s t e r o l v a l u e s o f human a d u l t s f e d t e s t d i e t s o f d e f a t t e d soy f l o u r or extruded soy c o n c e n t r a t e tended t o be lower than the v a l u e s f o r the i n d i v i d u a l s on t h e n o n - t e s t or animal product ( b e e f , egg) d i e t . The mean v a l u e f o r c h o l e s t e r o l and range, i n p a r e n t h e s i s , f o r the n o n - t e s t , b e e f , eggs, soy f l o u r , soy c o n c e n t r a t e and blended wheat p r o t e i n d i e t s i n mg/100 mg were 209 ( 1 8 1 - 2 5 0 ) ; 200.5 (104-238); 206.8 (164-267); 180.4 (149-216); 191.3 ( 1 6 4 - 2 3 8 ) ; and 178.6 ( 1 4 3 - 1 9 2 ) , r e s p e c t i v e l y . Rhee and Smith (20) i n d i c a t e d t h e c h o l e s t e r o l c o n t e n t of ground beef augmented w i t h soy f l o u r decreased as the amount o f added soy i n c r e a s e d , due to the d i l u t i o n o f meat which c o n t a i n s c h o l e s t e r o l w i t h soy, which does not. However, i n t h e cooked p a t t i e s , the amounts of c h o l e s t e r o l were not s i g n i f i c a n t l y d i f f e r e n t from t h e a l l beef p a t t i e s c o n t a i n i n g 8 or 16% f a t , but i n the case o f the p a t t i e s c o n t a i n i n g 27% f a t , t h e p a t t i e s c o n t a i n i n g soy p r o t e i n c o n t a i n e d s i g n i f i c a n t l y higher l e v e l s of c h o l e s t e r o l . Some legumes, i n c l u d i n g raw soy or peanut f l o u r are known t o c o n t a i n c e r t a i n a n t i n u t r i t i o n a l f a c t o r s such as p r o t e i n a s e i n h i b i t o r s and h e m a g g l u t i n i n s or l e c t i n s ( 2 1 , 2 2 ) . These f a c t o r s can be i n a c t i v a t e d , f o r the most p a r t , by moist h e a t , d u r i n g processing. I n t e r e s t i n g l y , peanut f l o u r c o n t a i n e d more t r y p s i n i n h i b i t o r and l e c t i n than d i d soy f l o u r ( 2 2 ) . The c o n t r o v e r s y c o n c e r n i n g the allegëcT i n h i b i t o r y a c t i v i t y o f soy products t o non-heme i r o n has not yet been r e s o l v e d c o m p l e t e l y . R o d r i g u e z et a l . (23) d i s c u s s e d the presence o f p h y t a t e i n soy

*Unfortified

product.

(PER)

Maximum)

Protein E f f i c i e n c y Ratio (PER o f C a s e i n - 2.5) C a l o r i e s per 100 Grams

NUTRITIONAL DATA*

Mercury Lead Arsenic

HEAVY METAL (PPM)

2.1 330

2.1 340

O.05 » Z» 2' 11) · ϋ ^ r e c e n t l y , most soy protein technology was directed exclusively toward cured, pumped ( i . e . injected) whole pork products such as hams, shoulders, p i c n i c s , butts and loins Ç5, _6, 11). New and e x i s t i n g USDA guidelines regulating meat/non-meat combinations (13) have d i v e r s i f i e d interest i n soy protein injection/absorption technology to other selected muscle tissues (Table I ) . When properly a p p l i e d , soy protein brines can offer reduced c o s t , reduced f a t , reduced c a l o r i e , portion controlled and/or protein standardized foods with yields up to 200% of green weight while resembling the structure of whole muscle tissue ( 1 4 ) · 1

TABLE I .

1

WHOLE MUSCLE MEAT SYSTEMS ADAPTABLE TO INJECTION OR ABSORPTION PROCESSES Ham Roast Beef Corned Beef Turkey Ham Chicken Breast

B-B-Q Ribs Shrimp Salmon Fish F i l e t s Scallops

Proper selection of soy protein i s c r i t i c a l to successful brine formulation and finished product quality (Table I I ) · TABLE I I .

CRITICAL CHARACTERISTICS OF SOY PROTEIN PRODUCTS FOR USE IN INJECTION OR ABSORPTION PROCESSES -Protein Content -Dispersibility -Solubility -Brine S t a b i l i t y -Brine Viscosity -Color -Moisture Retention -Flavor -Legal Standards

92

PLANT PROTEINS

Soy Protein Products To Consider

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch008

Advances i n soy protein processing technology have allowed extensive d i v e r s i f i c a t i o n of protein product applications. More sophisticated soy protein products now manufactured have more f u n c t i o n a l i t y , better performance, more consistency and better flavor than commerci a l l y a v a i l a b l e d e f a t t e d soy f l o u r and g r i t s (50% p r o t e i n d r y basis). Among these products are improved textured soy f l o u r s , concentrates, and isolates (50%, 70% and 90% protein dry basis, r e s p e c t f u l l y ) , functional and non-functional soy protein concentrates (70% protein dry basis) and highly soluble, highly functional isolated soy proteins (90% protein dry basis) (6^8, 14-18). Textured Soy Proteins. Textured vegetable proteins, primarily textured f l o u r s and concentrates (50% protein and 70% protein, dry basis, r e s p e c t f u l l y ) are widely used i n the processed meat industry to provide meat-like structure and reduce ingredient costs (3-6, 9-10). Available i n a variety of s i z e s , shapes, colored or uncolored, flavored or unflavored, f o r t i f i e d or u n f o r t i f i e d , textured soy proteins can resemble any basic meat ingredient. Beef, pork, seafood and poultry applications are possible (3, 4-7, 15, 19)· Proper p r o t e i n selection and hydration i s c r i t i c a l to achieving superior finished product q u a l i t y . Textured proteins have v i r t u a l l y no solub i l i t y and, thus, no a b i l i t y to penetrate into whole muscle t i s s u e . Therefore, textured soy proteins are inherently r e s t r i c t e d to coarse ground (e.g. sausage) or fine emulsion (e.g. weiners and bologna) products, and comminuted and reformed ( i . e . restructured) meat products. None are used i n whole muscle absorption or i n j e c t i o n applications (2-4, 6^, 11). Soy Protein Concentrates. Both non-functional (low or no s o l u b i l i ty) and functional (good s o l u b i l i t y , emulsification capacity, and d i s p e r s i b i l i t y ) soy protein concentrates (70% protein, dry basis) are commercially available for use i n meat products (2-4, 6^, 9^, 15) · Normally, a h i g h l y f u n c t i o n a l product w i t h no harsh or b i t t e r flavors i s desirable. When used to replace lean meat, non-hydrated c o n c e n t r a t e can be used at l e v e l s up to 6-7% i n f i n i s h e d nons p e c i f i c emulsion meats. Higher replacement l e v e l s or formulas with s p e c i f i c c o s t / n u t r i t i o n requirements may use soy protein concentrate with a judicious amount of textured soy protein ( 6 ) . Excellent y i e l d s , cost savings, texture, flavor and nutrient p r o f i l e s are possible. However, most soy protein concentrates lack s u f f i c i e n t s o l u b i l i t y or s u f f i c i e n t l y low v i s c o s i t i e s to be used i n brines f o r absorption or i n j e c t i o n into whole muscle t i s s u e . When l e g a l standards for protein content exist (13), more concentrate must be used to achieve l e g a l minimums. Brine v i s c o s i t i e s increase and uniform d i s t r i b u t i o n of brine components throughout the s p e c i f i c whole muscle piece i s r e s t r i c t e d . Finished product appearance and flavor are e a s i l y compromised. Thus, use of soy protein concentrates i n whole muscle applications i s l i m i t e d . I s o l a t e d Soy Proteins. Isolated soy proteins (90% protein dry basis) are highly d i s p e r s i b l e , highly soluble, highly functional soy products (8j _9, 11, 17, 18). Designed to replace a portion of

8.

YOUNG ET AL.

Soy Protein Products in Whole Muscle Meats

93

salt-soluble meat proteins, i s o l a t e d soy proteins bind water and f a t , s t a b i l i z e emulsions and help insure maintenance of structure i n f i n i s h e d cooked meats (3, 5, 6-9). Proper selection i s required to match s p e c i f i c f u n c t i o n a l i t y with cost, n u t r i t i o n , process and marketing needs (Table I I ) . Isolated soy protein can give excellent e m u l s i f i c a t i o n , low v i s c o s i t y , high moisture retention, and good s t a b i l i t y i n high s a l t c o n c e n t r a t i o n s , such as i n a b s o r p t i o n / i n j e c t i o n brines and within muscle tissue (5-6^, 9_, 11-12). Injection/Absorption of Soy Protein Containing

Brines

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch008

Table I l i s t s whole muscle meats which can be adapted to the i n j e c tion or absorption of brines containing soy protein. Special considerations and guidelines (9, 12) can be taken into account with s p e c i f i c goals are defined (Tables III and IV)· TABLE I I I .

FORMULA CONSIDERATIONS -Process -Ingredient -Nutritional -Marketing -Acceptability -Legal -Economic

TABLE IV.

NUTRITIONAL GUIDELINES

-Reduced Oil/Fat -Reduced Cholesterol -Increased Protein -Reduced Sweetener -Reduced Calorie -Vitamin/Mineral F o r t i f i c a t i o n Injection Process. Brines containing soy protein (Table V) may be i n j e c t e d d i r e c t l y into large, whole muscle pieces such as roast beef, ham, e t c . ( 5-£, 11-12). Injection i s appropriate when tissue pieces are large, firm, and able to withstand the physical action of the i n j e c t i o n process. Injection i s normally accomplished by use of a mechanical ("stitch") pump. Brine i s forced into various areas of the whole muscle piece through i n j e c t o r needles and d i s t r i b u t e d according to needle configuration, s i z e , number and type. Even d i s t r i b u t i o n of brine within each muscle piece i s assured by tumbling or "massaging" injected muscle i n a rotating tumbler. Vaccum may, or may not, be applied to improve brine component d i s t r i b u t i o n throughout the t i s s u e . Injected and tumbled product can then be appropriately cooked, cooled, and packaged. Finished products exhibit whole muscle features including appearance, f l a v o r , color and s l i c i n g c h a r a c t e r i s t i c s (6, 9^, 11-12). In addition, s i g n i f i c a n t cost savings are achieved while s a t i s f y i n g U.S.D.A. guidelines (13).

PLANT PROTEINS

94 TABLE V.

Recommended Brine Formulas for 50% Brine Injection Into Selected Whole Muscle Tissues

Ingredient Water Isolated Soy Protein Salt Dextrose Sodium Tripolyphosphate Cure Spices/Flavors

Roast Beef Corned Beef Percent 86.3 82.2 82.6 7.5 7.5 7.5 5.0 7.0 6.5 2.0 2.0 — 1.2 1.2 1.2 O.2 O.1 — as desired as desired as desired

Total

100.0

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch008

Ham

100.0

100.0

Absorption Process. It i s possible to absorb brines containing soy protein (Table VI) into unground, fresh muscle t i s s u e . Most adaptable are small pieces or trimmings with larger available surface area as compared to large muscle pieces more applicable to i n j e c t i o n processing. This can Include pork, beef, mutton, lamb, venison, turkey, chicken, f i s h f i l l e t s , shrimp, e t c . (3. 9^ 11-12). F i n e l y ground, comminuted or chopped tissues are not normally compatible with absorption technology. Absorption can be used to aid the "restructuring" of pieces which have been reduced i n size into a larger whole muscle structure or to process i n d i v i d u a l l y defined pieces ( e . g . f i s h f i l l e t s , shrimp) without "restructuring" (6, 9 ) . In general, absorption of brines containing soy protein into muscle tissue i s applicable when: 1. Injection i s not possible (meat pieces are too small or f r a g i l e to handle the mechanical stress of the s t i t c h pump)· 2. Meat from less desirable portions (including tissue after boning and trimming) are to be combined ("restructured") into more desirable and uniform p r o d u c t s · 3. Prime pieces are needed to conform to various shapes and sizes of containers and packaging. 4. Uniform weights and sizes are required by combining ("restructuring") small and large pieces. 5. Specifications require removal of undesirable i n t e r n a l f a t , g r i s t l e , veins, e t c . , to y i e l d more desirable and n u t r i t i o n a l l y sound finished p r o d u c t s · 6. Tenderization of lesser grade whole muscle meat i s d e s i r a b l e . 7. Color uniformity i s a major concern. 8. Maintenance of whole muscle tissue i n t e g r i t y i s required. Brine containing soy protein can be e a s i l y absorbed into small muscle pieces by the use of gentle mechanical action ( e . g . tumbling). Again, vaccum may, or may not, be applied to the tumbling process. As brine i s absorbed into the muscle t i s s u e , release of natural myosin gives each piece the c a p a b i l i t y of being reunited or "restructured" into a larger whole muscle piece. Absorption of up to 100% over green weight i s possible. Since tissues remain p l i able, they can e a s i l y be molded or packaged into a variety of shapes as r e q u i r e d . Heat processing s o l i d i f i e s myosin exudate and soy p r o t e i n , thus, unifying small muscle pieces into a uniform mass which w i l l not separate during subsequent handling. When formula-

8. YOUNG ET AL.

95

Soy Protein Products in Whole Muscle Meats

ted properly, finished restructured products can retain up to 100% of absorbed brine after cooking ( i . e . no cooking loss) and products resemble, s l i c e and eat l i k e their whole muscle counterparts (3-6 9^, ii> J E ­ TABLE V I .

Recommended Brine Formulas for Brine Absorption into

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch008

Selected Whole Muscle Tissue Roast Beef Ingredient Water 82.1 Isolated Soy Protein 7.3 Salt 4.5 Dextrose 4.0 Sodium Tripolyphosphate 1.1 Spice/Flavoring as desired Total

100.0

Breast Chicken Percent 90.7 5.3 2.5

—

1.5 as desired 100.0

Shrimp 91.0 5.0 2.0

—

2.0 as desired 100.0

U . S . D . A . Regulatory Guidelines. In the U . S . , whole muscle meat products ( i . e . beef, corned beef, ham, pork l o i n s , e t c . ) , which have been absorbed or injected with soy protein containing b r i n e , must comply with the following guidelines (13): 1. Products must be appropriately labeled and standard USDA l a b e l ­ ing approval granted. 2. A l l other U.S.D.A. regulations ( e . g . use of phosphates) must be satisfied. 3. The non-meat protein product ( e . g . isolated soy protein) must contain a prescribed vitamin/mineral pre-mix. 4. The non-meat protein product must have b i o l o g i c a l quality of protein (including amino acids added) of not less than P . E . R . 2.0 (80% of casein) or an essential amino acid content (exclud­ ing tryptophan) of no less than 28% of t o t a l p r o t e i n . 5. The finished cooked product must contain at least 17% p r o t e i n . 6. Finished product must be labeled "Combination Product" (Ham, Roast Beef, Turkey, e t c . ) with an appropriate statement of minimum percent meat ingredient ( e . g . 70% Ham, 70% Roast Beef, etc.). Product which has been s e c t i o n e d and formed ( i . e . restructured) must be i d e n t i f i e d . Calculation of Brine Components. In order to s a t i s f y U.S.D.A. regu­ l a t i o n s , care must be taken during brine preparation so that f i n i s h ­ ed product protein meets or exceeds 17 percent. The following formula can be used to determine brine composition (isolated soy p r o t e i n , s a l t , dextrose, polyphosphate, e t c . ) ( 6 ) · Percent Dry Ingredient = Μ + Β i n Brine Β M = Percent Raw Meat - 100% Y » Percent Ingredient i n Uncooked, Injected Product Β = Percent Injected Brine X

PLANT PROTEINS

96

Example - Raw meat (21% protein) to be injected to 50% over raw weight. Maintain 17% protein i n 70% meat finished/cooked combina­ tion using isolated soy protein. Assume isolated soy protein i s 92% protein. 17% Protein = (70 χ .21) + (Υ χ .92) Therefore, Y = Amount isolated soy protein i n uncooked, pumped product = 2.5 percent M = 100 percent Β = 50 percent

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch008

Amount Isolated Soy Protein i n Brine

=

100

+

50

« « s

50

T y p i c a l selected brine formulas for i n j e c t i o n of roast beef, corned beef and ham are given i n Table V. Brines for absorption technologies given i n Table VI are calculated s i m i l a r l y and may only d i f f e r i n minor brine components ( i . e . s a l t , seasonings, e t c . ) . Economics. Tables VII, VIII, IX and X summarize savings (based on ingredient prices, delivered Chicago, F a l l , 1985) and yields p o s s i ­ b l e when applying soy protein, i n j e c t i o n , absorption and restruc­ turing technologies to the processing of whole muscle meats · Although s i g n i f i c a n t y i e l d increases and savings are possible, extensive new opportunities can result from the development of new products and new product a p p l i c a t i o n s . TABLE VII.

COW

TOP ROUND - 50% INJECTION PROCESS

Cow Top Round Brine: Water Isolated Soy Protein Salt Sodium Tripolyphosphate Dextrose Flavor Total Ingredient Cost Finished Cooked Weight Cost Per l b . Finished Savings Per l b . Finished % Savings

Control 100.0 l b s .

Inj ected 100.0 l b s .

100.0 l b s .

43.0 3.4 2.5 O.7 O.3 O.1 150.0

$117.00 88.0 l b s .

lbs. lbs. lbs. lbs. lbs. lbs. lbs.

$120.00 132.0 l b s . $O.91 $O.42 35.9%

8.

YOUNG ET AL. TABLE VIII.

Soy Protein Products in Whole Muscle Meats TURKEY ROLL - 35% ABSORPTION/RESTRUCTURE PROCESS

Turkey Breast (Boneless) Brine: Water Isolated Soy Protein Salt Sodium Tripolyphosphate Spice Total

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch008

Ingredient Cost Finished Cooked Weight Cost Per l b . Finished Savings Per l b . Finished % Savings

Control 100.0 l b s .

Absorbed 100.0 l b s .

100.0 l b s .

30.5 l b s . 2.3 l b s . 1.4 l b s . O.5 l b s . O.3 l b s . 135.0 l b s .

$222.00 90.0 l b s . $2.47

— —

$237.67 121.5 l b s . $1.96 $O.51 20.6%

TABLE IX. BOILED SHRIMP - 25% ABSORPTION PROCESS

70-90 P&D Raw Shrimp Brine : Water Isolated Soy Protein Sodium Tripolyphosphate Salt Total Ingredient Cost Finished Cooked Weight Cost Per l b . Finished Savings Per l b . Finished % Savings TABLE X.

Control 100.0 l b s .

100.0 l b s . $250.00 72.0 l b s . $3.47

— —

Absorbed 100.0 l b s . 23.0 l b s . 1.3 l b s . O.5 l b s . O.2 l b s . 125.0 l b s . $251.83 95.0 l b s . $2.65 $O.82 24.0%

SMOKED CHUM SALMON - 33% INJECTION PROCESS

Chum Salmon Brine: Water Isolated Soy Protein Salt Sodium Tripolyphosphate Sodium N i t r i t e Sodium Erythorbate Total Ingredient Cost Finished Cooked Weight Cost Per l b . Finished Saving Per l b . Finished % Savings

Control 100.00 l b s .

Injected 100.00 l b s .

100.00 l b s .

29.60 l b s . 1.70 l b s . O.90 l b s . O.70 l b s . O.03 l b s . O.07 l b s . 133.00 l b s .

$175.00 72.0 l b s . $2.43

— —

$177.00 107.0 l b s . $1.65 $O.78 32.1%

97

P L A N T PROTEINS

98

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch008

New

Product Opportunities

Injection and absorption of brines containing soy protein into whole muscle meats can be used to develop a v a r i e t y of new product con­ cepts designed to meet s p e c i f i c formula guidelines (Table I I I ) . Through simple brine reformulation finished meats can be made to comply with desired or l e g a l requirements · Possible are whole muscle foods with reduced f a t , reduced c h o l e s t e r o l , reduced sodium, increased protein, reduced simple sugars ( i . e . sweeteners) and/or reduced c a l o r i e s (3, _6, 12, 14). Finished products such as these can be used as d i r e c t consumer goods or as ingredients i n other engineered systems. These, i n t u r n , may i n c l u d e p o r t i o n and nutrient controlled meals or d i e t s , frozen entrees, sandwiches, e t c . Thus, by properly applying the proper soy protein ingredient and brine injection/absorption technologies to control of costs, y i e l d s , and nutrient p r o f i l e s , new product concepts are possible while maintaining the structure, function and i n t e g r i t y of whole muscle tissues. LITERATURE CITED 1. 2. 3. 4. 5.

6. 7. 8. 9.

10. 11. 12.

13. 14. 15. 16. 17. 18. 19.

Brown, W. L. J Am Oil Chemists Soc., 1979, 56 (3), 316-319. I n g l e t t , M. J . ; Inglett, G. E. Food Products Formulary, Avi Publishing Co., Inc., Westport, CT, 1982, Volume 4, 89-101. "Ingredient Update 1985", Archer-Daniels-Midland Company, Chicago, IL, 1985. J u l , M. J Am Oil Chemists Soc., 1979, 56 (3), 313-315. L o n g , L.; Komarik, S. L.; T r e s e l e r , D. K. Food Products Formulary, Avi Publishing Company, Inc., Westport, CT, Volume 1, 130-183. "Meat Products Update", Archer-Daniels-Midland Company, Chicago, IL, 1983. Nowacki, J . A. J Am Oil Chemists Soc., 1979, 156 (3), 328-329. Waggle, D. H.; Decker, C. D.; Kolar, C. W. J AM Oil Chemists Soc., 1981, 58 (3), 341-342. Young, L. S. "Soy Protein Products i n Processed Meat and Dairy Foods", Presented at World Soybean Research Conference, Ames, IA, 1984. Kadane, V. V. J Am Oil Chemists Soc., 1979, 56 (3), 330-333. Desmyter, Ε. Α.; Wagner, T. J . J Am Oil Chemists Soc., 1979, 56 (3), 334-336. Young, L. S. "Use of Soy P r o t e i n Products i n I n j e c t e d and Absorbed Whole Muscle Seafood", Presented at A t l a n t i c Fisheries Technical Conference, Boston, MA, 1985. Federal Register, 105, 21761, 1976. Bonkowski, Α., and Taylor, G., unpublished data. Campbell, M. F. J Am Oil Chemists Soc., 1981, 58 (3), 259-261. K i n s e l l a , J . E. J Am Oil Chemists Soc., 1979, 56 (3), 259-261. Ohren, J . A. J Am Oil Chemists Soc., 1981, 58 (3), 333-335. Wilke, H. L.; Waggle, D. H.; Kolar, C. F. J Am Oil Chemists Soc., 1979, 56 (3), 259-261. S i p o s , E. F.; Endres, J . G.; Tybor, P. T.; Nakajima, Y. J Am Oil Chemists Soc., 1979, 56 (3), 320-327.

RECEIVED February 10, 1986

9 Effect of Dietary Protein On Skeletal Integrity in Young Rats Faustina Bohannon and Gur Ranhotra

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch009

Nutrition Research, American Institute of Baking, Manhattan, KS 66502

A number of nutrients affect bone integrity early in l i f e . While the role of certain minerals and vitamins bearing on skeletal integrity is well established, that of protein remains controversial, especially when consumed in excessive amounts. Protein-included calciuric effect as observed in adult man and animals may also occur early in l i f e and thus conceivably affect peak bone mass adversely, particularly when calcium intakes may be marginal. In studies reported here (test model: young female rats), i t was found that a diet approaching adequacy in protein and based equally on plant and animal sources would favor some parameters which bear on skeletal mass at maturity more than other combinations of protein consumed. S e v e r a l f a c t o r s , d i e t - r e l a t e d and o t h e r s , a f f e c t bone mass, and thus skeletal integrity early in l i f e . I t i s suspected that i n d i v i d u a l s w i t h l a r g e bone mass a c q u i r e d e a r l y i n l i f e (peak bone mass) a r e l e s s l i k e l y to d e v e l o p o s t e o p o r o s i s — t h i n n i n g o f b o n e s — i n l a t e r y e a r s than i n d i v i d u a l s w i t h l e s s e r bone mass ( 1 - 3 ) . W h i l e the d i e t a r y i n adequacy of c e r t a i n m i n e r a l s and v i t a m i n s t h a t a f f e c t s k e l e t a l mat u r i t y a d v e r s e l y i s w e l l documented, f o r p r o t e i n our c o n c e r n c e n t e r s around the e x c e s s i v e i n t a k e of t h i s n u t r i e n t . P r o t e i n - i n d u c e d c a l c i u r i c e f f e c t o b s e r v e d i n a d u l t man and a n i m a l s i s i m p l i c a t e d by some (4-6)as a c o n t r i b u t o r y f a c t o r i n the e t i o l o g y o f o s t e o p o r o s i s . P r o t e i n - i n d u c e d c a l c i u r i a , i f o c c u r r i n g e a r l y i n l i f e , may c o n t r i b u t e to an e a r l y onset of o s t e o p o r o s i s by a d v e r s e l y a f f e c t i n g the peak bone mass, e s p e c i a l l y when c a l c i u m i n t a k e may be m a r g i n a l . The s t u d i e s r e p o r t e d h e r e were u n d e r t a k e n to examine t h i s l a t t e r p o s s i b i l i t y under c o n d i t i o n s w h e r e i n the s o u r c e of d i e t a r y p r o t e i n a l s o varied. M a t e r i a l s and

Methods

Six p r o t e i n s o u r c e s — t w o p l a n t - d e r i v e d and f o u r a n i m a l - d e r i v e d — w e r e used i n t h i s 2 x 3 f a c t o r i a l type study ( T a b l e I ) . D i e t s were formu-

0097-6156/86/0312-0100S06.00/0 © 1986 American Chemical Society

9.

BOHANNON AND RANHOTRA

Effects of Protein on Skeletal Integrity

101

l a t e d u s i n g t h r e e c o m b i n a t i o n s o f p r o t e i n s o u r c e s , t o c o n t a i n 10% o r 30% p r o t e i n . D i e t s were complete i n a l l n u t r i e n t s r e q u i r e d by t h e r a t (7) except c a l c i u m which was p r o v i d e d a t 60% o f t h e r e q u i r e m e n t level. C a l c i u m (O.3%), phosphorus (O.4%), magnesium, z i n c , sodium and p o t a s s i u m l e v e l s were a l l e q u a l i z e d between d i e t s . Additional i n f o r m a t i o n on d i e t s i s p r o v i d e d e l s e w h e r e ( 8 ) . Table

I.

Experimental

D i e t No.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch009

Level (%)

Design

( 2 x 3 Factorial)

Dietary Protein Type (% o f T o t a l ) Plant Animal a

A Β C

10 10 10

67 50 33

33 50 67

D Ε F

30 30 30

67 50 33

33 50 67

b

a

A s bread: Bread was made w i t h w h i t e wheat f l o u r , wheat g l u t e n and d e f a t t e d soy f l o u r . ^Sources used: Cooked ground b e e f , parmesan c h e e s e , non­ f a t d r y m i l k and egg w h i t e powder. Weanling female r a t s were used as t h e t e s t model i n t h e s e studies. They were housed i n d i v i d u a l l y (10 r a t s / d i e t ) and o f f e r e d d i e t and d e i o n i z e d water ad l i b i t u m f o r 5 months. Apparent c a l c i u m and phosphorus a b s o r p t i o n and u r i n a r y Ca and Ρ l o s s e s were measured on c o l l e c t i o n s made the l a s t f i v e days each month. U r i n e volume and pH v a l u e s were a l s o r e c o r d e d . Other d a t a (growth r e s p o n s e , serum Ca and Ρ l e v e l s , femur m i n e r a l c o m p o s i t i o n , femur s t r e n g t h and d e n s i t y , and femur h i s t o l o g y ) were o b t a i n e d a t t h e end o f t h e 5-month f e e d i n g study. D e t a i l s o f t h i s and t h e a n a l y t i c a l methods used a r e p r e s e n t ­ ed e l s e w h e r e ( 8 ) . A l l d a t a were s u b j e c t e d t o a p p r o p r i a t e s t a t i s t i c a l analyses. R e s u l t s and D i s c u s s i o n P h y s i o l o g i c a l Responses. The v a r i o u s p h y s i o l o g i c a l r e s p o n s e s mea­ s u r e d i n r a t s a t t h e end o f t h e 5-month f e e d i n g p e r i o d a r e summarized i n T a b l e I I . These r e s p o n s e s were o b t a i n e d on d i e t s which were com­ p l e t e i n a l l r e q u i r e d n u t r i e n t s except p r o t e i n and c a l c i u m . Protein was p r o v i d e d a t a m a r g i n a l (10%) o r e x c e s s i v e (30%) l e v e l w h i l e c a l ­ cium was p r o v i d e d a t a s u b m a r g i n a l l e v e l . These l e v e l s r e p r e s e n t p a t t e r n s o f i n t a k e t y p i c a l o f t h e American p o p u l a t i o n . W i t h t h e e x c e p t i o n o f d i e t Β (10% p r o t e i n d i e t based e q u a l l y on p l a n t and a n i m a l p r o t e i n s o u r c e s ; T a b l e I ) , t h e body weight g a i n s of r a t s ( T a b l e I I ) were s i g n i f i c a n t l y h i g h e r ( T a b l e I I I ) when f e d 30% r a t h e r than 10% p r o t e i n d i e t s . Weight g a i n s on d i e t Β e q u a l l e d o r approached g a i n s o b s e r v e d on 30% p r o t e i n d i e t s ( d i e t s D - F ) . D i e t Β a l s o showed t h e h i g h e s t d i e t u t i l i z a t i o n e f f i c i e n c y as t h e d i e t : g a i n r a t i o s suggest ( T a b l e I I ) . I r r e s p e c t i v e o f t h e p r o t e i n s o u r c e s

a

b

(5-Month E x p e r i m e n t )

245+23 2130+80 8.8+O.8 639+24 O.42+O.04 6389+240 8519+320 10.1+O.3 3.4+O.7 O.50+O.03 69.9+O.3 25.1+1.0 10.7+O.8

233+22 2034+105 8.7+O.4 610+32 O.45+O.04 6102+316 8134+420 10.1+O.4 3.3+O.3 O.48+O.04 70.2+O.8 26.0+O.4 10.7+O.6

205+14 2026+67 9.9+O.5 203+7 O.40+O.05 6078+200 8104+266 9.9+O.3 3.1+O.3 O.46+O.03 70.2+O.5 25.7+O.6 12.9+O.7

233+4 2003+52 8.6+O.3 200+5 O.37+O.03 6008+155 8011+207 9.9+O.4 3.3+O.3 O.48+O.04 69.9+O.6 25.1+2.0 12.4+O.5

214+17 1960+97 9.2+O.6 196+10 O.38+O.02

5880+291 7840+388 9.8+O.3 3.2+O.6 O.45+O.02 70.6+O.3 26.5+1.3 12.5+O.1 deviation.

Ε

D

C

3

Β

Diets

P h y s i o l o g i c a l Responses Of R a t s

A

II.

V a l u e s show a v e r a g e (9-10 r a t s p e r d i e t ) + s t a n d a r d 'Fat-free, moisture-free b a s i s .

b

b

Body wt. g a i n (g) D i e t i n t a k e (g) Diet:gain (ratio) P r o t e i n i n t a k e (g) Kidney wt. (g/100 g. wt. g a i n ) C a l c i u m i n t a k e (mg) Phosphorus i n t a k e (mg) Serum Ca (mg/dl) Serum Ρ (mg/dl) Femur d r y wt. (g) Femur a s h (%) Femur C a (%) Femur P (%)

Parameter

Table

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch009

6333+281 8444+375 9.9+O.2 3.3+O.5 O.52+O.04 70.4+O.6 24.9+O.4 10.9+O.4

240+23 2111+94 8.8+O.5 633+28 O.42+O.04

F

9.

Effects of Protein on Skeletal Integrity

BOHANNON AND RANHOTRA

used, high p r o t e i n d i e t s - i n d u c e d ney ( T a b l e s I I and I I I ) . Table

III.

significant

103

enlargement of the k i d ­

S t a t i s t i c a l Analysis: F V a l u e s For Parameters I n c l u d e d In T a b l e I I a

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch009

Level Body wt. g a i n Diet intake Diet : gain Protein intake Kidney wt. Ca i n t a k e Ρ intake Serum Ca Serum Ρ Femur wt. Femur ash Femur Ca Femur Ρ

:

20.2*** 18.6*** 10.5** 62.9*** 27.2*** 18.6*** 18.6*** 4.7 O.5 18.3*** O.6 2 3 143.4*** n s

ns

ns

n s

Dietary Type 4.3* 4.6** 7.2** 3.9* O.8 4.6* 4.6** O.8 O.5 3.4* 3.6* 6.6** 2.3 ns

ns

ns

n s

Protein L e v e l χ Type ns

1.8 O.6 6.0** 1.8 3.2* O.6 O.6 1.2 O.1 2.0 2.7 O.6 O.3 ns

ns

ns

ns

ns

ns

n s

n s

ns

ns

ns, not s i g n i f i c a n t *, P ζ

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch010

10.

BODWELL

119

Utilization of Trace Minerals in Humans

Some of the apparent d i s c r e p a n c i e s between s t u d i e s (often between s t u d i e s based on long-term f e e d i n g vs those i n v o l v i n g s i n g l e t e s t meals) can, i n p a r t , be explained by the r e s u l t s of a recent study by Lynch e t al. (56). In t h i s study, the heme-iron and the non-heme i r o n were s e p a r a t e l y l a b e l e d with d i f f e r e n t i r o n i s o t o p e s . The a d d i t i o n of soy p r o t e i n to beef caused a marked decrease i n non-heme i r o n a b s o r p t i o n ( 5 . 1 vs 1 . 9 % ) . However, a marked i n c r e a s e was observed i n the a b s o r p t i o n of the heme i r o n upon i n c l u s i o n of the soy p r o t e i n (increased from 3 3 . 1 to 4 2 . 1 % ) . The amount of t o t a l i r o n absorbed was decreased by the i n c l u s i o n of soy ( O . 4 3 mg i n s t e a d of O.56 mg); however, the decrease was not as marked as would have been suggested by the r e s u l t s of the e a r l i e r s t u d i e s and might not be d e l e t e r i o u s during long-term consumption. Lynch e t a l . (5J7) found non-heme i r o n a b s o r p t i o n s , as measured by s i n g l e t e s t meals, f o r black beans, l e n t i l s , mung beans s p l i t peas, and whole soybeans to be low ( O . 8 4 to 1 . 9 1 % ) . T h i s suggests that many commonly consumed legumes are poor sources of i r o n ; whether legumes other than soy may have an " o f f s e t t i n g enhancing e f f e c t on heme-iron a b s o r p t i o n cannot be predicted. Z i n c . Some recent s t u d i e s on the e f f e c t s of soy p r o t e i n on z i n c u t i l i z a t o n are summarized i n Table IV. Young and Janghorbani (4j4) and I s t f a n et a l . (46) compared the e f f e c t s of soy i s o l a t e or soy concentrate and d r i e d skim milk as p r o t e i n sources i n multi-day feeding p e r i o d s . Zinc a b s o r p t i o n s , measured by f e c a l monitoring of the e x t r i n s i c l a b e l g i v e n , were e q u i v a l e n t and no d e l e t e r i o u s e f f e c t s of soy p r o t e i n were observed. In a second study, I s t f a n e t a l . (47) fed egg p r o t e i n d i e t s f o r 10 days and then a soy concentrate d i e t f o r 82 days. Zinc absorptions were not decreased by feeding the soy concentrate d i e t . Sandstrom and Cederblad (39) fed s i n g l e t e s t meals of chicken, beef, chicken or beef plus soy f l o u r or soybeans. The amount of z i n c i n the t e s t meal a f f e c t e d a b s o r p t i o n (Table IV) but not soy f l o u r per se. Higher l e v e l s of z i n c r e s u l t e d i n lowered a b s o r p t i o n s . Janghorbani e t a l . ( 5 8 ) fed i s o n i t r o g e n o u s d i e t s to 10 s u b j e c t s f o r 12 days. Both an i n t r i n s i c l a b e l (chicken) and e x t r i n s i c l a b e l s were used. Zinc absorptions from an a l l - c h i c k e n d i e t and from a 50% c h i c k e n - 5 0 % soy i s o l a t e d i e t were e q u i v a l e n t . Solomons et a l . (59) fed 5 or 10 s u b j e c t s d i e t s i n which milk, soy i s o l a t e , and beef (or mixtures of these) were p r o t e i n sources; f o r the milk and/or soy d i e t s , absorptions were s i m i l a r ; " f r a c t i o n a l " absorptions from beef bologna may have been higher than from soy bologna (Table IV). In the a b s o r p t i o n study conducted by I s t f a n e t a l . (47), z i n c balances were a l s o determined. Mean z i n c balances were p o s i t i v e and serum z i n c l e v e l s were w

f

(46)

(47)

(39)

Zinc a b s o r p t i o n s were e q u i v a l e n t ; mean values o f (a)29 and (b)26% Zinc a b s o r p t i o n s not d i f f e r e n t ; mean values of (a)31% and (b) 23%; f o r seven 12-day p e r i o d s of soy d i e t , mean values v a r i e d from 19 t o 32% Absorptions were (a) 36.2, (b) 20.4, (c) 24.7, (d) 16.5, (e) 19.6, (f) 24.4, and (g) 15.3%; a b s o r p t i o n appeared t o depend on zinc intake level

Six s u b j e c t s f e d formula d i e t s w i t h p r o t e i n provided by (a) egg (10 days) o r soy concen­ t r a t e (82 days); e x t r i n s i c z i n c l a b e l ( f e c a l monitoring method)

Six t o 11 s u b j e c t s consumed i s o n i t r o g e n o u s t e s t meals with primary p r o t e i n source being (a) c h i c k e n , (b) beef, (c) c h i c k e n + soy f l o u r , (d) beef + soy f l o u r , (e) soybeans, (f) chicken + z i n c , (g) beef + z i n c ; e x t r i n s i c z i n c l a b e l (whole body r e t e n t i o n measured)

(44)

Ref.

E i g h t s u b j e c t s f e d (10 days) formula d i e t s with e i t h e r (a) DSM o r (b) soy p r o t e i n concen­ t r a t e as p r o t e i n source; e x t r i n s i c z i n c l a b e l ( f e c a l monitoring method)

Absorptions (37-41%) e q u i v a l e n t among 3 d i e t s

Results

E f f e c t s of Soy P r o t e i n on Zinc U t i l i z a t i o n i n Humans.

F i v e s u b j e c t s consumed (14 days) formula d i e t s with p r o t e i n provided from e i t h e r (a) d r i e d skim milk (DSM) (b) DSM + soy i s o l a t e (50:50 p r o t e i n b a s i s ) , o r (c) soy i s o l a t e ; e x t r i n s i c z i n c l a b e l ( f e c a l monitoring method)

Absorption S t u d i e s

Description

Table IV.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch010

c/3

ζ

70

Ο Η m

Mean z i n c balances v a r i e d (+O.14 t o +1.38mg/day) f o r 7 12-day balances; serum z i n c l e v e l s constant a c r o s s 82 days Mean balances f o r days 15-21 not d i f f e r e n t ; although p o s i t i v e , mean balances f o r days 29-35 were lower f o r (a) and (b) compared to (c) Mean z i n c balances lower and n e g a t i v e , -2.39mg/day f o r (b); +3.25mg/day f o r (a); plasma z i n c l e v e l s lower f o r (b); p o s s i b l y d e l e t e r i o u s e f f e c t s of " r e s i d u a l " EDTA a p p a r e n t l y not determined

Subjects (16 or 17) consumed meals w i t h >70% of p r o t e i n from (a) t e x t u r e d soy, (b) soy i s o l a t e or (c) animal p r o t e i n sources, each f o r 35 days

F i v e s u b j e c t s consumed (a) animal p r o t e i n d i e t or (b) soy p r o t e i n ( f l o u r , i s o l a t e ) d i e t f o r 3 months; soy products "washed" with EDTA

Studies

Six s u b j e c t s f e d formula d i e t s w i t h p r o t e i n provided by soy concentrate (82 days)

Balance

Mean a b s o r p t i o n s were (a) 41, (b) 34, (c) 41, (d) 30 and (e) 41%; no d i f f e r e n c e s between ( a ) , (b), ( c ) ; (e) may have "favored z i n c a b s o r p t i o n " over (d).

F i v e or 10 s u b j e c t s f e d (12-14 days) d i e t s with (a) nonfat d r i e d m i l k (b) soy i s o l a t e , (c) milk & i s o l a t e , (d) soy i s o l a t e bologna and (e) beef bologna; e x t r i n s i c z i n c l a b e l s used ( f e c a l monitoring method) f

Absorptions of z i n c e q u i v a l e n t between d i e t s w i t h s i m i l a r z i n c i n t a k e s ; a b s o r p t i o n s higher with low z i n c i n t a k e

Ten s u b j e c t s fed (12 days) i s o n i t r o g e n o u s d i e t s w i t h a l l p r o t e i n from c h i c k e n meat or 50% from c h i c k e n and 50% from soy i s o l a t e ; i n t r i n s i c (chicken) and e x t r i n s i c l a b e l s used ( f e c a l monitoring method)

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch010

(41)

(40)

(47)

(59)

(58)

122

PLANT PROTEINS

unchanged across the 82-day p e r i o d of feeding soy concentrate. In the study by Bodwell e t a l . (40) mean balances were lower f o r textured soy and soy i s o l a t e d i e t s , compared to an animal p r o t e i n d i e t , but were s t i l l p o s i t i v e . Conversely, Cossack and Prasad (41) observed negative balances when a d i e t c o n t a i n i n g soy i s o l a t e plus textured soy was fed f o r 3 months. However, as noted above, whether or not the EDTA used to "wash" the soy products was completely removed is unknown.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch010

Reasons f o r Discrepancies As noted above, disagreement has o f t e n been observed among d i f f e r e n t s t u d i e s on the e f f e c t s of f i b e r , p h y t i c a c i d and p r o t e i n source on mineral u t i l i z a t i o n . Some p o s s i b l e reasons i n c l u d e : (a) estimates of absorption from s i n g l e meals (with or without previous consumption of the same foods used i n the t e s t meal which may also a f f e c t r e s u l t s ) may not always be e q u i v a l e n t to r e s u l t s from multi-day balance s t u d i e s , (b) i n balance s t u d i e s , the f a i l u r e to allow s u f f i c i e n t time (e.g., 1-2 weeks or more) f o r adaptation may a l t e r the f i n d i n g s , (c) v a r i a t i o n s i n the compositions of meals or d i e t s , i n c l u d i n g mineral l e v e l s , between s t u d i e s may i n f l u e n c e the r e s u l t s obtained, and (d) the persons used as subjects vary and t h i s may have an a f f e c t . In a d d i t i o n , i n the f i b e r s t u d i e s , the l e v e l s , types, and p a r t i c l e s i z e of f i b e r fed have v a r i e d widely and l e v e l s of other p o s s i b l y confounding components (e.g., c a f f e i n e , t a n i n s , oxalates) may have d i f f e r e d . P r a c t i c a l Implications Numerous s t u d i e s (e.g., 60-63) have evaluated the n u t r i t i o n a l mineral status of v e g e t a r i a n s . Most consume r e l a t i v e l y high l e v e l s of f i b e r and some probably consume a r e l a t i v e l y high l e v e l of p h y t i c a c i d . Although exceptions occur, i n general t h e i r mineral s t a t u s has been adequate. Obviously, adaptation occurs; t h i s has been shown c l i n i c a l l y (34,35). I t thus seems u n l i k e l y that increased intakes of vegetable p r o t e i n products pose long term r i s k s f o r those accustomed to non-vegetarian d i e t s . Literature Cited 1. 2. 3. 4. 5.

Berner, L.A. and M i l l e r , D.D. JAOCS (In P r e s s ) . Sandstead, H.H. Am. J . C l i n Nutr. 1982, 35, 809. Morck, T.A. and Cook, J.D. Cereal Foods World 1981, 260, 667. Kelsay, J.L. Cereal Chem. 1981, 58, 2. Kelsay, J.L. Am. J . Clin. Nutr., 1978, 31, 142.

10.

BODWELL

6. 7.

8. 9. 10.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch010

11. 12. 13. 14.

15. 16. 17. 18. 19. 20.

21. 22. 23. 24. 25. 26. 27.

Utilization of Trace Minerals in Humans

Bodwell, C.E. Cereal Foods World, 1983, 23, 343. Bodwell, C.E. and Hopkins, D.T. In "New P r o t e i n Foods, V o l . 5, Seed Storage P r o t e i n s " ( A l t s c h u l , A.M., and Wilcke, H.L., Eds.), Academic Press, N.Y., (1985) pp. 221-257. Solomons, N.W. Am. J . Clin. Nutr. 1982, 35, 1048. Davies, N.T. In "Dietary F i b e r In Health and Disease" (Vahouny, G.V., and Kritchevsky, D., Eds.), Plenum Pres, N.Y., 1982, pp. 105-116. Smith, J.C., J r . , M o r r i s , E.R. and Ellis, R. In "Zinc D e f i c i e n c y In Human Subjects" ( Prasad, A.S. Cabdar, A.O., Brewer, G.J., Aggett, P.J., Eds.), A.L. L i s s , N.Y, 1983, pp. 147-169. Erdman, J.W., J r . Cereal Chem. 1981, 58, 21. Erdman, J.W., J r . and Forbes, R.M. JAOCS 1981, 58, 489. Turnland, J.R. Cereal Foods World, 1982, 27, 152. Bothwell, T.H., Clydesdale, F.M., Cook, J.D., Dallman, P.R., H a l l b e r g , L., Van Campen, D. and Wolf, W.J. "The E f f e c t s of Cereals and Legumes on Iron Availability," I n t e r n a t l . N u t r i t i o n a l Anemia C o n s u l t a t i v e Group, The N u t r i t i o n Foundation, Washington, D.C., 44 pages, 1982. Kies, C. (Ed.) " N u t r i t i o n a l B i o a v a i l a b i l i t y of Iron", ACS SYMPOSIUM SERIES 203, American Chemical S o c i e t y , Washington, D.C., 1982. I n g l e t t , G.E. (Ed). " N u t r i t i o n a l B i o a v a i l a b i l i t y of Z i n c , " ACS SYMPOSIUM SERIES 210, American Chemical S o c i e t y , Washington, D.C., 1983. Monsen, E.R., H a l l b e r g , L., L a y r i s s e , M., Hegsted, D.M., Cook, J.D., Mertz, W., and F i n c h , C.A. Am. J . Clin. Nutr. 1978, 31, 134. Reinhold, J.G. In Reference 15, pp. 143-161. Guthrie, B.E. and Robinson, M.F. Fed. Proc. 1978, 37, 254. Sandstead, H.H., Munoz, J.M. Jacob, R.A., Klevay, L.M., Reck, S.J., Logan, G.M., J r . , D i n t z i s , F.R., I n g l e t t , G.E., and Shuey, W.C. Am. J . Clin. Nutr. 1978, 31, S180. M o r r i s , E.R. and Ellis, R. In Reference 15, pp. 121-141. M o r r i s , E.R. and Ellis, R. In Reference 16, pp. 159-172. Andersson, Η., Navert, Β., Bingham, S.A., Englyst, H.N. and Cummings, J.H. Br. J . Nutr. 1983, 50, 503. Simpson, K.M., M o r r i s , E.R. and Cook, J.D. Am. J . Clin. Nutr. 1981, 34, 1469. Sandberg, A.-S., Hasselblad, C. and Hasselblad, K. J. Nutr. 1982, 48, 185. Van Dokkum, W., Wesstra, A. and Schippers, F.A. Br. J . Nutr. 1982, 47, 451. Kelsay, J.L., B e h a l l , K.M., and Prather, E.S. Am. J . Clin. Nutr. 1979, 32, 1876.

123

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28. Kelsay, J.L., Jacob, R.A., and Prather, E.S. Am. J. Cln. Nutr. 1979, 32, 2307. 29. Kelsay, J.L., C l a r k , W.M., Herbst, B.J., and Prather, E.S., Fed. Proc. 1979, 38, 767. 30. I s m a i l - B e i g i , F., Reinhold, J.G., F a r a d j i , B., and Abadi, P., J. Nutr. 1977, 107, 510. 31. Drews, L.M., K i e s , C., and Fox, H.M., Am. J. Clin. Nutr. 1979, 32, 1893. 32. Papakyrikos, H., Kies, C., and Fox, H.M., Fed. Proc. 1979, 38, 549. 33. Kies, C., Fox, H.M., and Beshgetoor, D., Cereal Chem. 1979, 56, 133. 34. Kies, C., Young, E. and McEndree, L. In Reference 16, pp. 8-126. 35. Kies, C. and McEndree, L. In Refernce 16, pp. 183-198. 36. Turnland, J.R., King, J.C., Keyes, W.R., Gong, B. and M i c h e l , M.C. Am. J. Clin. Nutr. 1984, 40, 1071. 37. Kelsay, J.J. In Reference 16, pp. 127-143. 38. H a l l b e r g , L. and Rossander, L. Am. J. Clin. Nutr. 1982, 36, 514. 39. Sandstrom, B. and Cederblad, A. Am. J. Clin. Nutr. 1980, 33, 1778. 40. Bodwell, C.E., Smith, J.C., Judd, J., S t e e l e , P.D., Cottrell, S.L., Schuster, E., S t a p l e s , R., XII I n t e r n a t i o n a l N u t r i t i o n Congress, (Abstr), San Diego, CA (1981). 41. Cossack, Ζ.T. and Prasad, A.S. Nutr. Res. 1983, 3, 23. 42. G i l l o o l y , M., Bothwell, T.H., Torrance, J.D., MacPhail, A.P., Derman, D.P., Bezwoda, W.R., M i l l s , W. and C a r l t o n , R.W. Br. J. Nutr. 1983, 49, 331. 43. Navert, Β., Cedarblad, A. and Sandstrom, B. In Reference 25. 44. M o r r i s , E.R. and Ellis, R. 1986. In "Trace Element Metabolism In Man And Animals-IV." ( M i l l s , C.F., Aggett, P.J., Bremner, I . , Chesters, J.K., Eds.) Cambridge U n i v e r s i t y Press, London, 1986 (In Press). 45. Young, V.R., and Janghorbani, M. (1981). C e r e a l Chem. 1981, 58, 12. 46. I s t f a n , Ν., Murray, E., Janghorbani, M., and Young, V.R. J. Nutr. 1983, 113, 2516. 47. I s t f a n , Ν., Murray, Ε., Janghorbani, M., Evans, W.J., and Young, V.R. J. Nutr. 1983, 113, 2524. 48. Morck, T.A., Lynch, S.R., and Cook, J.D. Am. J. Clin. Nutr. 1981, 34, 2630. 49. Cook, J.D., Morck, T.A., and Lynch, S.R. Am. J. Clin. Nutr. 1981, 34, 2622. 50. Morck, T.A., Lynch, S.R., and Cook, J.D. Am. J. Clin. Nutr. 1981, 36, 219. 51. Cook, J. Data p u b l i s h e d in Reference 14.

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10. BODWELL

Utilization of Trace Minerals in Humans

52. S t e k e l , A. Data p u b l i s h e d in Reference 14. 53. M o r r i s , E.R., Bodwell, C.E., M i l e s , C.W., Mertz, W., Prather, E.S., and Canary, J.J. Fed. Proc. 1983, 42, 530. 54. M i l e s , C.W., Bodwell, C.E., M o r r i s , E.R., Mertz, W., Canary, J.J., Prather, E.S., Fed. Proc. 1983, 42, 529. 55. Bodwell, C.E., M i l e s , C.W., M o r r i s , E.R., Mertz, W., Canary, J.J., and Prather, E.S., Fed. Proc. (1983) 42:529. 56. Lynch, S.R., Dassenko, S.A., Morck, T.A., Beard, J.L., and Cook, J.D. Am. J. Clin. Nutr. 1985, 41, 13. 57. Lynch, S.R., Beard, J.L., Dassenko, S.A. and Cook, J.D. Am. J. Clin. Nutr. 1984, 40, 42. 58. Janghorbani, M., I s t f a n , N.W., Pagounes, J.O., Steinke, F.H., and Young, V.R. Am. J. Clin. Nutr. 1982, 36, 537. 59. Solomons, N.W., Janghorbani, Μ., T i n g , B.T.G., Steinke, F.H., C h r i s t e n s e n , Μ., Bijlani, R., I s t f a n , N. and Young, V.R. J. Nutr. 1982, 112, 1809. 60. Anderson, B.M., Gibson, R.S. and Sabry, J.H. Am. J. Clin. Nutr. 1981, 34, 1042. 61. Harland, B.F. and Peterson, M. J. Am. D i e t e t . A. 1978, 72, 259. 62. Dwyer, J.T., D i e t z , W.H., J r . , Andrews, E.M. and Suskind, R.M. Am. J. Clin. Nutr. 1982, 35, 204. 63. S c h u l t z , T.D. and Leklem, J.E., J. Am. D i e t e t . A. 1983, 83, 27. RECEIVED March 17, 1986

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11 Protein-Procyanidin Interaction and Nutritional Quality of Dry Beans 1

W. E. Artz , B. G. Swanson, B. J. Sendzicki, A. Rasyid, and R. E. W. Birch

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch011

Food Science and Human Nutrition, Washington State University, Pullman, WA 99164-6330

Thermodynamic analysis of the temperature dependance of procyanidin binding to bovine serum albumin (BSA) and bean glycoprotein G-1 suggested predominantly hydrophobic and hydrophilic binding, respectively. A cis-parinaric acid fluorescence assay for surface hydrophobicity supported amphiphilic interactions of procyanidin. Heat denatured G-1 had a surface hydrophobicity greater than native G-1. Procyanidin dimer and trimer inhibited trypsin digestion of BSA. In vitro digestibility and Tetrahymena-Protein Efficiency Ratio (t-PER) were inversely related to procyanidin concentration. Procyanidin intubation restricts rat growth and damages intestinal villi. Procyanidins intubated with food or as dry beans were not as inhibitory as procyanidins intubated alone. Digestibility and PER of tempeh prepared with red beans and corn were less than the digestibility and PER of soybean tempeh. Tempeh, Rhizopus oligosporus, fermentation did not improve digestibility or nutritional quality of dry black beans.

The common dry bean, Phaseolus v u l g a r i s , is a grain legume consumed in large quantities around the world. Black and other colored beans provide appreciable protein, vitamins, minerals and calories f o r r u r a l and urban populations of developing countries. The n u t r i t i o n a l importance of beans is great since access to protein of animal o r i g i n is limited. Legumes and cereals, which contain complementary proteins, provide protein of greater quality than consumption of legumes or cereals alone. However, consumption of beans and cereals in a favorable n u t r i t i o n a l quality r a t i o and amount tends to be infrequent in developing countries. World production of legumes appears to be declining compared to production and greater y i e l d s of cereals. Legume production, however, is s t i l l encouraged i n t e r n a t i o n a l l y to f i x atmospheric nitrogen and contribute to increased s o i l f e r t i l i t y in developing countries. Dry 1

Current address: Food Science, University of Illinois, Urbana, IL 61801. 0097-6156/86/0312-0126506.00/0 © 1986 American Chemical Society

11. ARTZ ET AL.

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127

beans are also an excellent source of complex carbohydrates, f i b r e and polyunsaturated fatty acids. However, dry beans have several undesirable attributes such as enzyme i n h i b i t o r s , phytates, flatus factors, l e c t i n s , allergens and condensed tannins that constrain n u t r i t i o n a l quality unless destroyed or removed. This paper presents research data that delineate the relationship of dry bean proteins to dry bean procyanidins, and discusses the constraints protein-procyanidin interaction places on n u t r i t i o n a l quality of dry beans.

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch011

Proteins in Legumes Proteins present in the seeds of legumes are primarily of two types: 1) enzymatic and s t r u c t u r a l metabolic proteins responsible for normal c e l l u l a r a c t i v i t i e s including the synthesis of s t r u c t u r a l proteins, and 2) storage proteins. The storage proteins and reserves of carbohydrates and o i l s are synthesized during seed development (1). Storage proteins occur within the c e l l in discreet protein bodies (Figure 1) that develop late during maturation of bean seeds (2). The quantity of protein in dry beans ranges from 18 to 25% (180 - 250 g/kg) dry weight. Protein fractionation studies of Phaseolus vulgaris L . have generated three major soluble protein fractions: phaseolin ( G l ) , globulin (G2) and albumin (3-4). Considerable confusion surrounds the nomenclature of seed proteins of common beans. Phaseolin is reportedly the preferred t r i v i a l designation for the globulin-1 ( G l ) , glycoprotein II or v i c i l i n , a 6.9S protein which aggregates to form the 18S tetramer at pH 4.5 05, Ο . Globulin-1 ( G l ) , globulin-2 (G2) and albumin represent 36-46%, 5-12% and 12-16% of the t o t a l seed p r o t e i n , respectively, although there appeared to be some contamination between the l a t t e r two fractions after usual i s o l a t i o n procedures (4). Environmental factors such as geographic location and growing season substantially influence protein content of dry beans (6). Polypeptide c l a s s i f i c a t i o n of Gl f r a c t i o n has been well documented and permits c l a s s i f i c a t i o n of bean c u l t i v a r s into three groups: Tendergreen, Sanilac and Contender, on the basis of electrophoresis banding patterns (7). The major storage protein in beans, globulin-1 ( G l ) , exhibits a pH dependent polymerization that was u t i l i z e d in p u r i f i c a t i o n (8). At pH 3.8 to 5.4, Gl exists as a tetramer, while at pH 6.4 to 10.5, Gl exists as a monomer of MW 163,000 (9). The i s o e l e c t r i c point of Gl is pH 4.4 - 5.6. Gl s o l u b i l i t y is independent of pH from pH 2.5 to 12.0 (10) in O.5F NaCl. A crude extract of Gl was prepared for p u r i f i c a t i o n on cyanogen bromide activated Sepharose. Tannins/Procyanidins Tannins are one of several a n t i n u t r i t i o n a l factors present in dry beans. Any polyphenolic compound that precipitates proteins from an aqueous solution can be regarded as a tannin (11). Tannins precipitate proteins due to functional groups that complex strongly with two or more protein molecules, building up a large cross-linked protein-tannin complex (12). Naturally-occurring food legume tannins are reported to interact with enzyme and non-enzyme proteins to form complexes that

128

PLANT PROTEINS

r e s u l t in i n a c t i v a t i o n o f d i g e s t i v e enzymes and p r o t e i n i n s o l u b i l i t y ( 1 3 ) . J j i v i t r o and in v i v o s t u d i e s i n d i c a t e t h a t bean t a n n i n s d e c r e a s e p r o t e i n d i g e s t i b i l i t y and p r o t e i n q u a l i t y ( 1 4 ) . Condensed t a n n i n s and p r o c y a n i d i n s a r e terms used t o d e s c r i b e the same g e n e r a l c l a s s of compounds, p l a n t p h e n o l i c s t h a t a r e polymers o f the f l a v a n - 3 - o l s ( F i g u r e 2 ) , (+) c a t e c h i n and/or (-) e p i c a t e c h i n (15). P r o c y a n i d i n s heated in a l c o h o l and a c i d w i l l produce c o l o r e d compounds s t r u c t u r a l l y r e l a t e d t o a n t h o c y a n i d i n s (16). P r o c y a n i d i n polymers c o n s i s t o f c h a i n s of 5, 7, 3 , 4 t e t r a h y d r o x y f l a v a n - 3 - o l c o n n e c t e d by C ( 4 ) - C ( 6 ) o r C ( 4 ) - C ( 8 ) bonds (15). P r o c y a n i d i n s o c c u r f r e e and not as g l y c o s i d e s ( 1 7 ) . An a d d i t i o n a l hydroxy group can sometimes be found on the Β r i n g o f the f l a v a n - 3 - o l a t the 5 p o s i t i o n . Some hydroxy groups on the Β r i n g may be m e t h o x y l a t e d (18) and the methoxyl groups may a f f e c t protein-procyanidin interaction. P r o c y a n i d i n c o n c e n t r a t i o n s range from 1.5 t o 18.6 mg o f p r o c y a n i d i n per gram o f whole bean f l o u r ( 4 ) . P r o c y a n i d i n s a r e found in g r e a t e r c o n c e n t r a t i o n s in c o l o r e d beans t h a n in w h i t e beans, most o f which a r e l o c a t e d in the seed c o a t , t e s t a or h u l l . f

?

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch011

f

Methods D i m e r i c and t r i m e r i c c a t e c h i n were p r e p a r e d by r e d u c t i o n o f d i h y d r o q u e r c e t i n w i t h sodium b o r o h y d r i d e in the p r e s e n c e o f c a t e c h i n (19). P o l y m e r i z a t i o n was f o l l o w e d on s i l i c a g e l TLC u s i n g an a c e t o n e : t o l u e n e : f o r m i c a c i d (60:30:10) s o l v e n t ( 2 0 ) . The v i s u a l i z a t i o n agent was v a n i l l i n (1 g/100 ml) in 70% v / v s u l f u r i c acid/water. C a t e c h i n , c a t e c h i n dimer and c a t e c h i n t r i m e r appeared as red s p o t s w i t h r e s p e c t i v e Rf v a l u e s of O.66, O.54 and O.43. The f l a v a n - 3 , 4 - d i o l appeared as a p u r p l e spot w i t h an Rf v a l u e o f O.63. S e p a r a t i o n o f d i m e r i c and t r i m e r i c c a t e c h i n was a c c o m p l i s h e d w i t h Sephadex LH-20 u s i n g an e t h a n o l : w a t e r (45:55) s o l v e n t . P u r i t y o f the p r o c y a n i d i n was e v a l u a t e d w i t h r e v e r s e d - p h a s e HPLC i s o c r a t i c a l l y w i t h 4% a c e t i c a c i d in w a t e r . T r i t i u m - l a b e l l e d p r o c y a n i d i n dimer and t r i m e r were s y n t h e s i z e d s i m i l a r l y w i t h 25 mCi t r i t i a t e d sodium b o r o h y d r i d e added to the r e a c t i o n m i x t u r e o v e r a 20 min p e r i o d under nitrogen. B i n d i n g constants of l i g a n d , t r i t i u m l a b e l l e d c a t e c h i n dimer and t r i m e r , t o d e f a t t e d b o v i n e serum a l b u m i n (BSA) and p u r i f i e d bean p r o t e i n G l were d e t e r m i n e d by the method d e v e l o p e d by S o p h i a n o p o u l o s e t a l . (23) w i t h an Amicon M i c r o p a r t i t i o n System MPS-1 (American Corp., Danvers, MA). S e p a r a t i o n o f the f r e e l i g a n d from the bound l i g a n d was a c c o m p l i s h e d by c o n v e c t i v e f i l t r a t i o n o f f r e e l i g a n d t h r o u g h an a n i s o t r o p i c , h y d r o p h i l i c YMT u l t r a f i l t r a t i o n membrane. The d r i v i n g f o r c e was p r o v i d e d by c e n t r i f u g a t i o n . P r o t e i n s were q u a n t i t a t i v e l y r e t a i n e d above the membrane w h i l e low m o l e c u l a r weight l i g a n d p a s s e d t h r o u g h the membrane. Binding c o n s t a n t s were d e t e r m i n e d by S c a t c h a r d p l o t a n a l y s i s (24-26). L i n e a r r e g r e s s i o n a n a l y s i s was used t o f i t the p o i n t s f o r the Scatchard p l o t . Procyanidin Binding

t o Bovine Serum Albumin

(BSA)

P o l y m e r i c p r o c y a n i d i n e x t r a c t i o n from b l a c k beans ( P h a s e o l u s v u l g a r i s L. cv. B l a c k T u r t l e Soup) and p u r i f i c a t i o n was a

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch011

ARTZ ET AL.

Nutritional Quality of Dry Beans

F i g u r e 1. S c a n n i n g e l e c t r o n m i c r o g r a p h o f P h a s e o l u s v u l g a r i s c o t y l e d o n showing p r o t e i n b o d i e s (P) and s t a r c h g r a n u l e s ( S ) . Bar = 10 Urn.

PROCYANIDIN B2 F i g u r e 2. dimer B2.

Structure

of epicatechin, catechin

and p r o c y a n i d i n

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PLANT PROTEINS

modification of the procedure of Strumeyer and Malin (21) and the procedure of Cansfield et a l . (22) using 80:20 r a t i o of acetone:water as primary extracting solvent, and LH-20 for clean-up. The method of Kato and Nakai (27) for determining protein surface hydrophobicity was adapted for evaluating procyanidin binding to BSA and G l . The procedure is based on the fact that the fluorescence quantum y i e l d of c i s - p a r i n a r i c acid increases 40-fold when c i s - p a r i n a r i c acid enters a hydrophobic environment from a hydrophilic environment. The digestion of BSA by trypsin in the presence of procyanidin dimer, procyanidin trimer and black bean procyanidin polymer was evaluated by discontinuous sodium dodecyl sulfate (SDS) slab gel electrophoresis and a p i c r y l sulfonic acid (TNBS) assay (28). Scatchard plots were used to determine the binding constants of procyanidins to BSA and bean globulin Gl at temperatures of 19, 29 and 39°C (Figures 3 and 4). Nu (v) is moles of ligand bound per mole of protein. L is the concentration of the free ligand. The equilibrium binding constant is equal to the negative slope of the corrected curve as determined by linear regression analysis from the Scatchard p l o t . Nonspecific binding is the binding of ligand to protein s i t e s possessing low a f f i n i t y (24). High a f f i n i t y binding must be corrected for nonspecific binding (25). Nonspecific binding was determined as the y-axis intercept of the extension of the lower a f f i n i t y binding curve. The lower a f f i n i t y nonspecific binding was subtracted from binding possessing the high a f f i n i t y to produce the corrected binding curve. The negative slope of the curve is equal to the equilibrium association binding constant and the x-axis intercept is equal to the moles of ligand bound per mole of protein. Thermodynamic analysis of the binding constants of BSA and procyanidin dimer and trimer from the Van't Hoff equation (29) indicates a reaction with a positive entropy change, a positive

Table I.

Binding Constants Gl

Temperature

Trimer (k) 74,000 42,000 27,000

19 29 39

Table I I .

Procyanidin Trimer Dimer Trimer

Enthalpy, entropy and free energy

Protein Gl BSA BSA

BSA Procyanidin Trimer Dimer (k) (k) 110,000 4,000 120,000 8,200 122,000 20,490

Enthalpy (H) (kcal/mole) - 9.26 14.9 O.96

Entropy (S) (eu) - 9.41 67.5 26.3

Free Energy (G) (kcal/mole) - 6.51 - 4.81 - 6.73

11. ARTZETAL.

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Nutritional Quality of Dry Beans

3000,

2500h+_ 2000 V/L

1500 SCATCHARO PLOT

1000 Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch011

Κ - 4000 COR. SCATCHARO PLOT

500

Figure 3,

Scatchard plot of BSA and procyanidin dimer at 19C.

25000r20000 - ,

1500oL

+

+ 4

V/L

Κ - 110000 + SCATCHARO PLOT COR. SCATCHARO PLOT .5

Figure 4.

1.5

Scatchard plot of BSA and procyanidin trimer at 19C.

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PLANT PROTEINS

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e n t h a l p y change and a n e g a t i v e f r e e e n e r g y , i . e . a spontaneous r e a c t i o n t h a t is t o t a l l y e n t r o p y d r i v e n ( T a b l e s I and I I ) . Since h y d r o p h o b i c i n t e r a c t i o n s a r e e n t r o p y d r i v e n , t h e b i n d i n g o f BSA t o p r o c y a n i d i n is h y d r o p h o b i c . In aqueous s o l u t i o n s , h y d r o p h o b i c i n t e r a c t i o n is v e r y i m p o r t a n t (30). Water m o l e c u l e s a t t h e s u r f a c e o f t h e h y d r o p h o b i c domain c r e a t e d by a n o n p o l a r s o l u t e r e a r r a n g e in o r d e r t o r e g e n e r a t e b r o k e n hydrogen bonds, b u t in d o i n g so c r e a t e a g r e a t e r degree o f l o c a l o r d e r t h a n e x i s t s in pure l i q u i d w a t e r , t h e r e b y p r o d u c i n g a d e c r e a s e in e n t r o p y (30). The d r i v i n g f o r c e f o r h y d r o p h o b i c i n t e r a c t i o n is the i n c r e a s e in e n t r o p y when t h e o r d e r e d w a t e r is r e l e a s e d t o t h e bulk water. Hydrophobic i n t e r a c t i o n s a r e entropy d r i v e n . C e r t a i n t y p e s o f n o n - c o v a l e n t i n t e r a c t i o n s such as hydrogen bonds, London i n t e r a c t i o n s and v a n d e r Waals i n t e r a c t i o n s a r e e n t h a l p y d r i v e n i n t e r a c t i o n s ( 2 6 ) ; heat is r e l e a s e d d u r i n g bond formation. The heat r e l e a s e d d u r i n g bond f o r m a t i o n s t a b i l i z e s t h e bonds. Hydrogen bonds, London i n t e r a c t i o n s and van d e r Waals i n t e r a c t i o n s a r e v a r i a n t s on t h e d i p o l e - d i p o l e i n t e r a c t i o n model, which i n c l u d e permanent and i n d u c e d d i p o l e s . T r i m e r i c p r o c y a n i d i n b i n d s more t i g h t l y t o BSA t h a n d i m e r i c p r o c y a n i d i n ( T a b l e I I ) . P a r t i t i o n c o e f f i c i e n t s o f d i m e r i c and t r i m e r i c c a t e c h i n between n - o c t a n o l and w a t e r i n d i c a t e p r o c y a n i d i n t r i m e r is more h y d r o p h o b i c t h a n p r o c y a n i d i n dimer. Increased b i n d i n g c o n s t a n t s o f t r i m e r r e l a t i v e t o dimer agree w i t h r e p o r t e d partition coefficients. Surface h y d r o p h o b i c i t y assays with c i s - p a r i n a r i c a c i d c o n f i r m t h e thermodynamic a n a l y s i s t h a t b i n d i n g of p r o c y a n i d i n t o BSA is h y d r o p h o b i c . Procyanidin Binding

t o Bean G l o b u l i n ( G l )

B i n d i n g o f p r o c y a n i d i n t r i m e r t o bean p r o t e i n G l was temperature dependent ( F i g u r e 5 ) . An i n c r e a s e in t e m p e r a t u r e r e s u l t e d in a l a r g e d e c r e a s e in t h e b i n d i n g c o n s t a n t ( T a b l e I ) . G l b i n d i n g t o p r o c y a n i d i n t r i m e r is spontaneous and h y d r o p h i l i c in n a t u r e . The b i n d i n g is d r i v e n by t h e l a r g e change in e n t h a l p y ( T a b l e I I ) . The type o f b o n d i n g i n v o l v e d between G l , a g l y c o p r o t e i n , and p r o c y a n i d i n is p r o b a b l y hydrogen b o n d i n g . E v a l u a t i o n of the G l i n t e r a c t i o n with p r o c y a n i d i n trimer with c i s - p a r i n a r i c a c i d confirmed that the b i n d i n g o f n a t i v e G l t o p r o c y a n i d i n t r i m e r is h y d r o p h i l i c ( F i g u r e 6). Heat-denatured Gl e x h i b i t e d a s u r f a c e h y d r o p h o b i c i t y g r e a t e r than t h a t o f n a t i v e G l . The i n c r e a s e was n o t unexpected s i n c e h y d r o p h o b i c groups a r e commonly o r i e n t e d towards t h e c e n t e r o f p r o t e i n s in aqueous s o l v e n t s . Heat d e n a t u r a t i o n o f p r o t e i n exposes h y d r o p h o b i c groups t o t h e s o l v e n t . B i n d i n g o f d e n a t u r e d G l t o bean p r o c y a n i d i n o l i g o m e r was p r e d o m i n a n t l y h y d r o p h o b i c . Common bean p r o c y a n i d i n s a r e c a p a b l e o f both h y d r o p h i l i c and hydrophobic i n t e r a c t i o n with p r o t e i n . H y d r o p h i l i c i n t e r a c t i o n s are f a v o r e d w i t h a h y d r o p h i l i c g l y c o p r o t e i n l i k e common bean g l o b u l i n G l , while hydrophobic i n t e r a c t i o n s are favored a f t e r p r o t e i n d e n a t u r a t i o n , when p r o t e i n h y d r o p h o b i c groups a r e exposed t o t h e solvent.

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11. ARTZETAL.

133

Nutritional Quality of Dry Beans

1

2

3

4

V F i g u r e 5. S c a t c h a r d G l a t 19C.

p l o t o f p r o c y a n i d i n t r i m e r and bean

F i g u r e 6. F l u o r e s c e n c e cis-parinaric acid.

globulin

o f G l (O.04%), p r o c y a n i d i n dimer and

134

PLANT PROTEINS

Trypsin Inhibition

Table I I I .

Percent Inhibition of the Trypsin Digestion of BSA

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Procyanidin Dimer Trimer Polymer

1 mg/ml 16.9 42.3 50.5

5 mg/ml 25.2 71.2 89.4

Trypsin digestion of BSA was inhibited by addition of procyanidin dimer, trimer and oligomer (Table I I I ) . Increased procyanidin concentration increased i n h i b i t i o n of the trypsin digestion of BSA. Increased procyanidin chain length also increased i n h i b i t i o n of trypsin digestion. Protease i n h i b i t i o n by procyanidin does not occur by i r r e v e r s i b l e binding of procyanidin to the active s i t e of the protease. Procyanidin is not a s p e c i f i c i n h i b i t o r for either trypsin or chymotrypsin, i . e . procyanidin does not i n h i b i t by binding i r r e v e r s i b l y to the active s i t e , rather procyanidin binds non-specifically to the enzyme and/or protein substrate. Since procyanidin does not bind s p e c i f i c a l l y to protease active s i t e s , but reacts n o n - s p e c i f i c a l l y , Scatchard plots indicate less than one mole of procyanidin is bound per mole of protein. With polymeric procyanidin, considerable c r o s s - l i n k i n g w i l l occur. Not a l l a n t i - n u t r i t i o n a l effects can be explained by high a f f i n i t y binding. Feeding Procyanidins Complete removal of procyanidin is not necessary to overcome anti-nutritional effects. Removal of most procyanidin or addition of s u f f i c i e n t protein w i l l overcome a n t i - n u t r i t i o n a l effects of procyanidins. Small concentrations of procyanidin can be e a s i l y overcome by adding protein. The most apparent n u t r i t i o n a l effect of feeding procyanidins at naturally occurring concentrations in plants, such as in sorghum grain (1-2%), are growth depression, poor feed efficiency ratios and increased f e c a l nitrogen (12). Protein Efficiency Ratio is a procedure to measure the r a t i o of weight gain to protein intake of weanling rats fed a diet with a single suboptimal 10% concentration of test protein. Tetrahymena-PER is a more rapid assay, using protozoa Tetrahymena pyriformis or Tetrahymena thermophila, as an alternative to the laboratory rat as a b i o l o g i c a l assay for protein quality. Good correlation between PER determined with the rat and Tetrahymena have been reported (14). In v i t r o d i g e s t i b i l i t y and Tetrahymena-PER are inversely related to procyanidin content (14). B i o a v a i l a b i l i t y , expressed as Tetrahymena growth, of bean globulin Gl in the presence of black bean procyanidins correlated well with in v i t r o d i g e s t i b i l i t y of the protein. Health consequences of procyanidins in the human diet are r e l a t i v e l y unknown, but the t o x i c i t y for human beings may be similar to the t o x i c i t y observed in experimental animals (12). Bender and Mohammidiha (31) proposed that increased fecal nitrogen from rats fed diets containing large quantities of cooked legumes was due to increased gastrointestinal mucosal c e l l turnover, rather than poor

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11. ARTZETAL.

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135

protein d i g e s t i b i l i t y . Fairweather-Tait et a l . (32) discovered that mucosal c e l l sloughing increased 35% in the small intestine of rats fed beans compared to rats fed a control d i e t . Physiological alterations such as damage to the mucosal l i n i n g of the gastrointestinal tract and increased cation excretion have also been demonstrated (33-35). Very great concentrations of dietary procyanidin, near 5%, can cause death (12). Increased fecal nitrogen or decreased nitrogen retention by animals fed procyanidin has been explained by either a reduced d i g e s t i b i l i t y of dietary protein or an increased excretion of endogenous protein (33). Explanations for the a n t i n u t r i t i o n a l aspects of procyanidins have centered around the a b i l i t y of procyanidin to bind protein. Rats intubated with 5.0% procyanidin developed coughing, sneezing, wheezing, o v e r a l l respiratory distress and severe dehydration, and were s a c r i f i c e d after 20 d. Gross pathological examination revealed moderate to large quantities of i n t e s t i n a l gas, distended i n t e s t i n a l walls and a translucent quality to the small i n t e s t i n a l mucosa. The duodenum was discolored, black-purple, for O.5 to 1.0 cm aboral to the p y l o r i c sphincter. The jejunum and ileum were thin-walled translucent and g a s - f i l l e d when compared to jejunum and ileum of control rats (36). H i s t o l o g i c a l examination of gastrointestinal tissues from rats intubated with 5% procyanidin revealed broad, short and fused v i l l i in the areas where the duodenal tissue was dissolved. Dietary procyanidin can damage v i l l i decreasing the absorptive surface area and a l t e r i n g the absorptive c a p a b i l i t y of the i n t e s t i n a l mucosa. Nutrient a v a i l a b i l i t y is reduced and dietary protein deficiency can r e s u l t . Gastrointestinal e p i t h e l i a l damage observed with p u r i f i e d procyanidin may be dose dependent. Intubations of 1.0 and O.5% procyanidin were not toxic over a four week period, yet resulted in areas of v i l l i shortening and broadening in some of the rats intubated. Growth rate reduction did occur with 1.0 and O.5% procyanidin intubation with food. Long term consumption of unpurified procyanidins contained in legumes had no detectable effect on the h i s t o l o g i c a l appearance of the gastrointestinal tract in rats consuming diets prepared with 40% black beans. Dry Bean Fermentation-Tempeh Tempeh, an Indonesian food generally produced from soybeans fermented by Rhizopus oligosporus, is more acceptable than cooked soybeans because, in p a r t , tempeh does not have the unacceptable beany flavor and flatus problem associated with soybeans. Tempeh prepared with small red beans or a small red bean/corn mixture were acceptable in c o l o r , sweeter and more fragrant in flavor and similar in texture to soybean tempeh. The PER and in v i t r o protein d i g e s t i b i l i t y of small red bean (1.69, 85.2) and small red bean/corn (2.15, 86.1) tempeh were less than the PER and in v i t r o protein d i g e s t i b i l i t y of soybean (2.63, 88.9) and soybean/corn (3.11, 90.2) tempehs (37). Tempeh fermentation does not improve the protein quality of common beans. The presence or absence of bean h u l l s did not s i g n i f i c a n t l y affect protein u t i l i z a t i o n from tempeh. The PER for white bean t r i a l s (1.47) improved when soaking water was discarded before the beans were cooked (1.70) and fermented (38).

PLANT PROTEINS

136

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Conclusions Common bean p r o t e i n and p r o c y a n i d i n i n t e r a c t i o n s can be h y d r o p h i l i c or h y d r o p h o b i c , depending on the s i t e s on the p r o t e i n a v a i l a b l e f o r interaction. Thermal p r o c e s s i n g can d e n a t u r e the p r o t e i n and change the type o f i n t e r a c t i o n p o s s i b l e . Once bean p r o t e i n is d e n a t u r e d , h y d r o p h o b i c i n t e r a c t i o n s between the p r o t e i n and p r o c y a n i d i n a r e likely. S i n c e the s t r e n g t h o f h y d r o p h o b i c i n t e r a c t i o n s i n c r e a s e s w i t h i n c r e a s e d in t e m p e r a t u r e , the i n t e r a c t i o n between p r o t e i n and p r o c y a n i d i n w i l l be enhanced d u r i n g t h e r m a l p r o c e s s i n g . Removal o f p r o c y a n i d i n w i l l be e a s i e s t p r i o r t o t h e r m a l p r o c e s s i n g . A c u t e l o n g term doses o f p r o c y a n i d i n s and food have a reduced t o x i c i t y compared to p r o c y a n i d i n i n t u b a t e d a l o n e . D i e t a r y l o n g term doses o f p r o c y a n i d i n s a r e n o r m a l l y e n c o u n t e r e d in human d i e t a r y p a t t e r n s in v a r i o u s a r e a s o f the w o r l d . Recommendations t o i n c r e a s e common bean consumption w i l l not r e s u l t in any a d v e r s e e f f e c t s t o p o p u l a t i o n s consuming l a r g e q u a n t i t i e s o f beans. Tempeh can be s u c c e s s f u l l y fermented w i t h common beans and bean/corn mixtures. However, the p r o t e i n d i g e s t i b i l i t y o r n u t r i t i o n a l q u a l i t y o f beans is not improved s u b s t a n t i a l l y by tempeh fermentation. Acknowledgments The a u t h o r s e x p r e s s thanks f o r a s s i s t a n c e from Dr. K i e t h Dunker, C h e m i s t r y Department, Dr. Ann H a r g i s , V e t e r i n a r y M i c r o b i o l o g y and P a t h o l o g y and Dr. Robert B e n d e l , S t a t i s t i c a l S e r v i c e s , Washington S t a t e U n i v e r s i t y . P a r t i a l f i n a n c i a l s u p p o r t f o r t h i s r e s e a r c h was p r o v i d e d by USAID T i t l e X I I Dry bean/Cowpea CRSP. P r o j e c t No. 0560, A g r i c u l t u r a l R e s e a r c h C e n t e r , C o l l e g e o f A g r i c u l t u r e and Home Economics, Washington S t a t e U n i v e r s i t y , P u l l m a n , WA 99164-6330. L i t e r a t u r e Cited 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

Sathe, S. K.; Deshpande, S. S.; Salunkhe, D. K. CRC C r i t i c a l Reviews Food S c i . Nutr. 1985, 20, 1-46. Hughes, J. S.; Swanson, B. G. Food Microstructure 1985, 4, 183-9. McLeester, R. C.; H a l l , T. C.; Sun, S. M.; B l i s s , F. A. Phytochem. 1973, 12, 85-93. Ma, Y.; B l i s s , F. A. Crop S c i . 1978, 17, 431-7. Buchbinder, B. U. Ph.D. Thesis, U n i v e r s i t y Wisconsin, Madison, 1980. H o s f i e l d , G. L.; Uebersax, Μ. Α.; I s l e i b , T. G. J. Amer. Soc. Hort. S c i . 1984, 109, 182-9. Brown, J. W. S.; Osborn, T. C.; B l i s s , F. H.; H a l l , T. C. Theor. Appl. Genet. 1981, 60, 245-250. Stockman, D. R.; H a l l , T. C.; Ryan, D. S. Plant Physiol. 1976, 58, 272-5. Sun, S. M.; McLeester, F. Α.; B l i s s , F. Α.; H a l l , T. C. J. Biol.Chem. 1974, 249, 2119-21. Sun, S. M.; H a l l , T. C. J. Agr. Food Chem. 1975, 23, 184-9. Swain, T.; Hillis, W. E. J. S c i . Food Agric. 1959, 10, 63-8. P r i c e , M. L.; Butler, L. G. Purdue University Agric. Exp. Sta. B u l l . No. 272, 1980, p. 37.

11.

13. 14. 15. 16. 17.

18.

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19. 20. 21. 22.

23.

24. 25. 26.

27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38.

A R T Z ET A L .

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Reddy, N. R.; Pierson, M. D.; Sathe, S. K.; Salunkhe, D. K. J. Amer. Oil Chem. Soc. 1985, 62, 541-9. Aw, T-L.; Swanson, B. G. J. Food S c i . 1985, 50, 67-71. Czochanska, Z.; Foo, L. Y.; Newman, R. H.; Porter, L. J.; Thomas, W. Α.; Jones, W. T. J. C. S. Chem. Comm. 1979, 375-7. Creasy, L. L.; Swain, T. Nature 1965, 208, 151-3. Haslam, E. In "Flavonoids and bioflavonoids-current research trends"; Farkas, L.; Gabor, M.; Kallay, F., Eds.; Elsevier S c i e n t i f i c Publishing Co.: N.Y., 1977, pp. 97-110. Brandon, M. J.; Foo, L. Y.; Porter, L. J.; Meredith, P. Phytochem. 1982, 21, 1953-7. Eastmond, R. J. Inst. Brewing 1974, 80, 188-92. Lea, A. G. H. J. S c i . Food Agric. 1978, 29, 471-7. Strumeyer, D. H.; Malin, M. J. J. Agric. Food Chem. 1975, 23, 909-14. Cansfield, P. E.; Marquardt, R. R.; Campbell, L. D. J. S c i . Food Agric. 1980, 31, 802-12. Sophianopoulos, J. Α.; Durham, S. J.; Sophianopoulos, A. J.; Ragsdale, H. L.; Cropper, W. P. Arch. Biochem. Biophys. 1978, 187, 132-7. Chamness, G. C.; McGuire, W. L. Steroids 1975, 26, 538-42. Norby, J. G.; Ottolenghi, P.; Jensen, J. Anal. Biochem. 1980, 102, 318-20. Tinoco, I.; Sauer, K.; Wang, J. C. "Physical Chemistry. Principles and applications in b i o l o g i c a l sciences"; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1978. Kato, Α.; Nakai, S. Biochim. Biophys. Acta 1980, 624, 13-20. Romero, J.; Ryan, D. S. J. Agric. Food Chem. 1978, 26, 784-8. Weiland, G. Α.; Minneman, K. P.; Molinoff, P. B. Nature 1979, 281, 114-7. Tanford, C. "The hydrophobic e f f e c t : formation of micelles and microbiological membranes"; John Wiley and Sons: NY, 1980. Bender, A. E.; Mohammidiha, H. Proc. Nutr. Soc. 1981, 40, 66A. Fairweather-Tait, S. J.; Gee, J. M.; Johnson, I. T. B r i t . J. Nutr. 1983, 49, 303-12. M i t j a v i l a , S.; Lacombe, C.; Carrera, G.; Derache, R. J. Nutr. 1977, 107, 2113-21. Motilva, M. J.; Martinez, J. Α.; Ilundain, Α.; Larralde, J. J. S c i . Food Agric. 1983, 34, 239-46. Rao, B. S. N.; Prabhavathi, T. J. S c i . Food Agric. 1982, 33, 89-96. Sendzicki, B. J. M.S. Thesis, Washington State University, Pullman, WA, 1985. Rasyid, A. M.S. Thesis, Washington State University, Pullman, WA, 1983. Birch, R. E.; Swanson, B. G.; Koos, R. M.; Finney, F. 45th Ann. Mtg. Inst. Food Technol., 1985, Abs. 170.

R E C E I V E D February 3, 1986

12 Acceptability and Tolerance of a Corn-Glandless Cottonseed Blended Food by Haitian Children 1

2,4

3

3,5

R. E. Hayes , Carolyn P. Hannay , J. I.Wadsworth ,and J. J. Spadaro 1

Olivet Nazarene College, Kankakee, IL 60901 Grace Children's Hospital, International Child Care, Port-au-Prince, Haiti Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, New Orleans, L A 70179

2

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch012

3

A lysine-fortified, corn-based Public Law 480-type food blend containing glandless cottonseed flour (CC) was found to be comparable in nutritional quality, maternal and child acceptability and child gastrointestinal tolerance to the extensively used U.S. Food-for-Peace Program food blend, corn-soy-milk (CSM). The double blind, four week supplementary feeding study was conducted among 157, mainly preschool age, children and their mothers at nutrition centers in the area of Port-au-Prince, Haiti. The proportion of components in CC were determined by computer to formulate the blend of highest protein quality as measured by chemical score. Animal protein was not used in CC in achieving PER and NPR values statistically comparable to those for CSM. The f e a s i b i l i t y o f u s i n g c o t t o n s e e d f l o u r to r e p l a c e soy f l o u r as a high p r o t e i n c o n t r i b u t o r t o U . S . Government food blends has been o f i n t e r e s t in r e c e n t y e a r s . P r e s e n t l y cottonseed f l o u r is not used to an a p p r e c i a b l e e x t e n t in human food in the U n i t e d S t a t e s . But, due t o expanding p o p u l a t i o n in d e v e l o p i n g c o u n t r i e s , i t may be necessary to use t h i s p r o t e i n r e s o u r c e more e f f i c i e n t l y . An investigation has been conducted to determine the s u i t a b i l i t y o f u t i l i z i n g g l a n d l e s s cottonseed f l o u r in P u b l i c Law 480 (known a l s o as the U . S . F o o d - f o r - P e a c e Program) blended f o o d s . The f i r s t stage of t h i s r e s e a r c h was to e s t a b l i s h a r a p i d computer formulation procedure to supplant a lengthy trial-and-error approach f o r d e t e r m i n i n g i n g r e d i e n t p r o p o r t i o n s needed to a c h i e v e b e s t p r o t e i n q u a l i t y in the b l e n d s U,2). A s e r i e s o f nine corn-based blends, containing flours of peanut, glandless c o t t o n s e e d , or c o t t o n s e e d / s o y combinations were then f o r m u l a t e d by the computer optimization technique described. Experimental s c r e e n i n g t e s t s compared these nine blends w i t h two standard P u b l i c 1

5

Current address: St. Thomas Hospital, Nashville, T N 37208. Retired. 0097-6156/86/0312-0138$06.00/0 © 1986 American Chemical Society

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139

Law 480 blends c o r n - s o y and c o r n - s o y - m i l k , w i t h r e s p e c t to p r o t e i n quality by animal assay, organoleptic quality and storage stability. Of the nine experimental blends, a blend of c o r n - g l a n d l e s s cottonseed, f o r t i f i e d with l y s i n e monohydrochloride, showed a h i g h p r o t e i n q u a l i t y and was comparable to c o r n - s o y - m i l k w i t h r e s p e c t to o v e r a l l f l a v o r q u a l i t y and in degree of flavor maintenance d u r i n g storage (3). T h i s p r e s e n t study d e s c r i b e s a comparative a c c e p t a b i l i t y and tolerance field test (4), the next step in determining the suitability of u s i n g a supplementary food m i x t u r e for small c h i l d r e n in d e v e l o p i n g c o u n t r i e s . I t was conducted in Haiti, mainly among preschool age childern. Modified corn-soy-milk (designated MCSM), a sweetened version of the leading U.S. F o o d - f o r - P e a c e Program blended f o o d , was t e s t e d a g a i n s t a sweetened experimental blend, corn-glandless cottonseed, fortified with l y s i n e monohydrochloride ( d e s i g n a t e d CC). H a i t i was a p a r t i c u l a r l y s u i t a b l e l o c a t i o n f o r comparative e v a l u a t i o n of these c o r n - b a s e d b l e n d s because corn is a major s t a p l e t h e r e , and because of the a v a i l a b i l i t y o f n u t r i t i o n c e n t e r s t h a t serve mothers w i t h young children. Supplementary f o o d s , such as those p r o v i d e d under P u b l i c Law 480, are o f t e n d i s t r i b u t e d a t the c e n t e r s . Experimental Blend Formu1ati o n , P r é p a r a t i o n . S e v e r a l sources were used to d e r i v e tfië" n u t r i t i o n a l c r i t e r i a For p r e s c r i b i n g blend c o m p o s i t i o n s and test quantities. C o l l e c t i v e l y , P r o t e i n A d v i s o r y Group ( d e s i g n a t e d PAG) g u i d e l i n e numbers 7 and 8 U,j5) and the general U . S . D . A . g u i d e l i n e s f o r g r u e l - t y p e foods (6,7J recommend: d a i l y dry weight of supplement; p r o t e i n c o n c e n t r a t i o n and q u a l i t y ; minimum l e v e l of f a t ( f o r adequate c a l o r i c d e n s i t y ) ; maximum l e v e l s f o r crude f i b e r and t o t a l a s h ; m o i s t u r e r a n g e ; and f o r t i f i c a t i o n w i t h v i t a m i n s , minerals and antioxidants. Because prior experience in field-testing blended foods has shown t h a t a d d i t i o n of sugar improved a c c e p t a b i l i t y , an 8 p e r c e n t sucrose l e v e l was used f o r both MCSM and CC (8 - J O ) .

T a b l e I . S p e c i f i c a t i o n s f o r the c o r n - g l a n d l e s s c o t t o n s e e d (CC) and m o d i f i e d c o r n - s o y - m i l k (MCSM) blends Component s p e c i f i c a t i o n

Blend CC

Total Protein ( a l l sources) T o t a l F a t ( a l l sources) Sugar N o n - f a t dry m i l k M i n e r a l premix V i t a m i n premix Utilizing

proximate

(*)

20.0 6.6 8.0 O.0 2.7 O.1

a n a l y s i s data

on a l l

MCSM (%)

20.0 6.6 8.0 15.0 2.7 O.1 blend c o n s t i t u e n t s

and

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amino acid analyses on the protein-containing components, the c o m p o s i t i o n of the c o r n - g l a n d l e s s cottonseed, lysine monohydroc h l o i d e blend was o p t i m i z e d by computer to o b t a i n the b e s t chemical score consistent with the criteria derived from the sources d e s c r i b e d above and l i s t e d in T a b l e I. The a d d i t i o n of sugar r e q u i r e d a d i f f e r e n t f o r m u l a t i o n f o r MCSM from the p r o p o r t i o n s s t i p u l a t e d by the commodity s p e c i f i c a t i o n (11). A l s o , in l i e u of the usual procedure of m i x i n g commodities in a g i v e n p r o p o r t i o n to f o r m u l a t e c o r n - s o y - m i l k , p r o t e i n and f a t percentage l e v e l s of MCSM were s e t i d e n t i c a l l y to those s p e c i f i e d f o r CC. Cornmeal, d e f a t t e d soy f l o u r and soy o i l p r o p o r t i o n s were then a d j u s t e d by computer to meet these c o n s t r a i n t s . The v i t a m i n premix p r o v i d e d the a n t i o x i d a n t s B.H.A. and B.H.T., each a t a l e v e l of O.0022 p e r c e n t (11) in both b l e n d s . Standard a n a l y t i c a l procedures were used to e v a l u a t e the c o m p o s i t i o n of i n g r e d i e n t s . Of the proximate a n a l y s e s , nitrogen, l i p i d s , and crude f i b e r were measured by American Oil Chemists S o c i e t y (AOCS) methods (12) and moisture and ash by A s s o c i a t i o n of Official Analytical Chemists (AOAC) methods (13L Amino acid a n a l y s e s were performed by g a s - l i q u i d chromatography (14) except for tryptophan, which was analyzed colormetrically T Î 5 ) . In a d d i t i o n to these a s s a y s , c e r t a i n t e s t s of i n g r e d i e n t s a f e t y or s p o i l a g e were a l s o performed, which space does not p e r m i t to be r e p o r t e d in t h i s paper, to a s s u r e t h a t i n g r e d i e n t s met a c c e p t e d standards f o r food s a f e t y ( 1 6 ) . The i n g r e d i e n t s of each blend were thoroughly mixed in a l a r g e ribbon blender. The entire food preparation and packaging o p e r a t i o n was c a r r i e d out in a s a n i t a r y manner. A q u a n t i t y of each blend was a p p r o p r i a t e l y subpackaged f o r the v a r i o u s physical, chemical and m i c r o b i o l o g i c a l t e s t s . In accordance w i t h the recommendation of PAG g u i d e l i n e number 8 (5), the CC and MCSM f o r f i e l d t e s t i n g were packaged in O.8 kilogram quantities (approximately 100 grams dry weight of supplement per day f o r one week). Each O.8 k i l o g r a m batch was weighed i n t o a 3.8 l i t e r ( f o u r q u a r t ) p o l y e t h y l e n e f r e e z e r bag, c l o s e d w i t h a t i e tape, and t h i s bag was then p l a c e d w i t h i n a 1.9 l i t e r (half-gallon) r i g i d c y l i n d r i c a l polyethylene container with a l i d t h a t was s e a l e d w i t h p l a s t i c t a p e . A 53 cc p l a s t i c measuring cup, f o r use in p r e p a r i n g g r u e l , was i n c l u d e d w i t h the f o o d . Numbers were a s s i g n e d to the CC and MCSM samples on a random b a s i s . There were f o u r O.8 k i l o g r a m packages prepared f o r each number, one f o r d i s t r i b u t i o n to each c h i l d ' s mother weekly f o r f o u r weeks. The p l a s t i c c o n t a i n e r s were packaged f o r shipment in f i b e r board drums and h e l d a t -18°C u n t i l food s a f e t y c l e a r a n c e s of the U.S. and Haitian governments were obtained. This clearance took a p p r o x i m a t e l y nine months. Chemical,Biological and Physical Tests on Blends. Reported chemical evaluations on the freshly prepared blends include proximate a n a l y s e s and amino a c i d a n a l y s e s . The same a n a l y t i c a l procedures d e s c r i b e d above f o r i n g r e d i e n t s were a l s o used on the blends. Three animal procedures ( p r o t e i n e f f i c i e n c y r a t i o , net p r o t e i n r a t i o , and p r o t e i n d i g e s t i b i l i t y ) were used to e v a l u a t e p r o t e i n quality. The AOAC (13) animal assay f o r p r o t e i n e f f i c i e n c y r a t i o

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12. HAYES ET AL.

Com-G landless Cottonseed Blended Food

141

(PER) was m o d i f i e d in s e v e r a l r e s p e c t s . The d i e t s were c a l c u l a t e d on a 10 p e r c e n t p r o t e i n l e v e l r a t h e r than on an isonitrogenous basis. T h i s was done because the n i t r o g e n f a c t o r s of the v a r i o u s b l e n d components v a r i e d a p p r e c i a b l y from the 6.25 n i t r o g e n f a c t o r assumed in the AOAC p r o c e d u r e . A composite n i t r o g e n f a c t o r f o r each blend was c a l c u l a t e d from a n a l y t i c a l r e s u l t s by d i v i d i n g the t o t a l amino a c i d c o n t e n t by the n i t r o g e n c o n t e n t . In t h i s manner, the composite n i t r o g e n f a c t o r s were determined to be 6.28 f o r MCSM and 5.91 f o r CC. A f u r t h e r d e v i a t i o n from the AOAC PER procedure was t h a t f i v e a n i m a l s r a t h e r than ten were used. The t e s t i n g l a b o r a t o r y p e r f o r m i n g the assays had been r o u t i n e l y u s i n g f i v e a n i m a l s f o r some time f o r t h i s t e s t and had found only a small d i f f e r e n c e in the standard e r r o r between r e s u l t s f o r f i v e versus ten animals. The conventional nitrogen factor of 6.25, as s p e c i f i e d in the AOAC p r o c e d u r e , was used f o r computing the Animal N u t r i t i o n Research C o u n c i l (ANRC) c a s e i n l e v e l . In the net p r o t e i n r a t i o (NPR) c a l c u l a t i o n ( 1 7 ) , 15-day growth and p r o t e i n i n t a k e data of a n i m a l s on the PER d i e t s were used. N i t r o g e n d i g e s t i b i l i t y ( p e r c e n t of n i t r o g e n i n t a k e absorbed) was determined on each animal on pooled data from the 8 t h through the 15th day of the PER t e s t . In a d d i t i o n t o the t e s t s d e s c r i b e d above, o t h e r c h e m i c a l , b i o l o g i c a l , p h y s i c a l , and p h y s i c o c h e m i c a l t e s t s were performed (16) which are n o t r e p o r t e d in t h i s paper because of space l i m i t a t i o n . These t e s t s are mainly concerned w i t h p r o d u c t s a f e t y , chemical s t a b i l i t y and sensory p e r c e p t i o n . F i e l d Test Protocol. Background i n f o r m a t i o n on t e s t methodology, n u t r i t i onal charac t e r i s t i c s , and food s a f e t y a n a l y t i c a l v a l u e s were r e q u i r e d by both the H a i t i a n and American Governments before sending the blended foods to H a i t i . In the H a i t i a n Government, a p p r o v a l was r e q u i r e d by the M i n i s t r y of H e a l t h and by i t s Bureau of N u t r i t i o n . Approval of the U.S. Government was g i v e n through the U.S. Department of Agriculture's Human Studies Review Committee. N u t r i t i o n a l c r i t e r i a f o r p r e s c r i b i n g the blend c o m p o s i t i o n s and q u a n t i t i e s used have been d e s c r i b e d above in the f o r m u l a t i o n section. P r o c e d u r a l c r i t e r i a used in the f i e l d t e s t are embodied in PAG g u i d e l i n e number 7 f o r human t e s t i n g of supplementary food mixtures (4.). This guideline requires t h a t human t e s t i n g be preceded by c o m p o s i t i o n a l and n u t r i t i o n a l s t u d i e s of the m i x t u r e being c o n s i d e r e d , assessment of food s a f e t y a s p e c t s and economic f e a s i b i l i t y evaluation. Economic f e a s i b i l i t y was not c o n s i d e r e d in t h i s case s i n c e the i n v e s t i g a t o r s were i n t e r e s t e d in a f u t u r e potential use of glandless cottonseed, which is not now e c o n o m i c a l l y c o m p e t i t i v e w i t h soy. C o m p o s i t i o n a l , n u t r i t i o n a l , and food s a f e t y s t u d i e s were p r e v i o u s l y conducted as d e s c r i b e d above [3) . The same types of e v a l u a t i o n were performed on foods a c t u a l l y sent to H a i t i . The H a i t i a n f i e l d t r i a l concerns one of the f o u r c a t e g o r i e s of human e v a l u a t i o n s o u t l i n e d by PAG g u i d e l i n e number 7 (4) , namely, a c c e p t a b i l i t y and tolerance t e s t s . Some of the f e a t u r e s of these t e s t s are t h a t : a t l e a s t some o f the t e s t i n g should take place in a c o u n t r y f o r which the p r o t e i n - r i c h food is i n t e n d e d ; the t e s t should be conducted w i t h c h i l d r e n in the age c a t e g o r i e s f o r which the p r o d u c t is i n t e n d e d ; both the t e s t and

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c o n t r o l groups should be of s i m i l a r s i z e ; a t l e a s t 20 i n d i v i d u a l s should be used in the t e s t ; the d u r a t i o n of the t e s t should be a t l e a s t 4 weeks; data a n a l y s i s should c o n s i d e r t h a t the m o t h e r ' s a c c e p t a b i l i t y response may i n f l u e n c e the c h i l d ' s response; and the p o s s i b i l i t y t h a t d i s e a s e processes might i n f l u e n c e a c c e p t a b i l i t y and t o l e r a n c e should be c o n s i d e r e d . R e f u s a l of the c h i l d to e a t the food is c o n s i d e r e d to be an i n d i c a t o r of poor p a l a t a b i l i t y . I n t o l e r a n c e is judged by n o t i n g p e r s i s t e n t g a s t r o i n t e s t i n a l u p s e t s . It is also suggested t h a t o t h e r clinical responses, such as a l l e r g i c r e a c t i o n s , be r e c o r d e d . C o n s i d e r a t i o n of the p r o v i s i o n s of PAG g u i d e l i n e number 7 determined test procedure, to be described, and also the composition of the q u e s t i o n n a i r e . The q u e s t i o n n a i r e a c t u a l l y used was a C r e o l e t r a n s l a t i o n o f the one shown in F i g u r e 1. The q u e s t i o n s were to be asked of each mother f o r each c h i l d by the n u t r i t i o n c l i n i c worker a f t e r the four-week f e e d i n g t r i a l . Question A concerns the child's a c c e p t a b i l i t y response. The c h i l d ' s eagerness t o e a t the food is used as a gauge of how w e l l the c h i l d l i k e d the f o o d . Item Β r e f l e c t e d the m o t h e r ' s o v e r a l l a c c e p t a b i l i t y response to the f o o d . The m o t h e r ' s e v a l u a t i o n of f o u r f a c t o r s i n f l u e n c i n g her a c c e p t a b i l i t y is p r o v i d e d f o r in item C. The f a c t o r s under i t e m D i n v o l v e the m o t h e r ' s e s t i m a t e o f whether c e r t a i n i n d i c a t o r s of g a s t r o i n t e s t i n a l r e a c t i o n change and the d i r e c t i o n of the change d u r i n g the i n t e r v a l the blended food was consumed. The mother was a l s o asked ( i t e m E) to p r o v i d e information t h a t would help investigators to check possible r e l a t i o n s h i p s between q u e s t i o n n a i r e responses and o t h e r foods eaten d u r i n g the t e s t i n t e r v a l . The blended foods were d i s t r i b u t e d to mothers a t f i v e n u t r i t i o n c e n t e r s in the P o r t - a u - P r i n c e area o f H a i t i . One o f the c o a u t h o r s , C a r o l y n P. Hannay, R.N., n u t r i t i o n i s t , s u p e r v i s e d food d i s t r i b u t i o n and c o l l e c t i o n of d a t a . A l l c h i l d r e n were to be 5 y e a r s of age or younger. Mothers had from one to f o u r c h i l d r e n p a r t i c i p a t i n g in the f i e l d t e s t . The mothers were grouped a c c o r d i n g to the number of c h i l d r e n t h a t they had p a r t i c i p a t i n g in the s t u d y . A r a n d o m i z a t i o n procedure was used f o r sample assignment to mothers w i t h two c h i l d r e n in the study, and then f o r mothers w i t h three c h i l d r e n , e t c e t e r a . F o r each mother d e s i g n a t e d to r e c e i v e a given blend ( e g . , MCSM), each c h i l d in her f a m i l y in the t e s t r e c e i v e d d i f f e r e n t sample numbers of the same b l e n d . D i f f e r e n t blends were not a s s i g n e d to the same mother. Mothers were given a d e m o n s t r a t i o n on how to prepare g r u e l from a dry b l e n d . W r i t t e n d i r e c t i o n s in C r e o l e were made a v a i l a b l e f o r use by n u t r i t i o n w o r k e r s . The f e e d i n g was to be done t h r e e times per day. Some f l e x i b i l i t y was allowed the mother in p r e p a r a t i o n of the g r u e l . The same r e c o n s i t i t u t i o n d i r e c t i o n s were given to mothers w i t h e i t h e r MCSM or CC, even though i t was known t h a t c o n s i s t e n c i e s of the two blends d i f f e r e d . No c l u e was g i v e n t h a t there were two b l e n d s . The experiment was d o u b l e - b l i n d . The a u x i l i a r y n u t r i t i o n i s t d i s t r i b u t i n g the food c o n t a i n e r s to the mothers d i d not know which b l e n d a c e r t a i n number r e p r e s e n t e d . She o n l y knew t h a t a given mother r e c e i v e d a sample w i t h a p a r t i c u l a r a s s i g n e d number f o r a certain child. Nor, of c o u r s e , was the mother t o l d t h a t the blended food she r e c e i v e d was of any p a r t i c u l a r t y p e . A O.8

12.

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Com-Glandless Cottonseed Blended Food

HAYES ET AL.

BLENDED FOOD QUESTIONNAIRE Q u e s t i o n s t o be a s k e d o f e a c h mother f o r e a c h c h i l d by t h e n u t r i t i o n worker a f t e r the four-week feeding t r i a l . Family

clinic

name:_ Age

C h i l d ' s f i r s t name:

How many c h i l d r e n o f t h i s f a m i l y a r e p a r t i c i p a t i n g 1n t h i s f e e d i n g

study?

B l e n d e d f o o d sample number :

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch012

A.

How d i d y o u r c h i l d l i k e Like

© Any B.

O.K.

Dislike

©

P u t an "X M I n one b l o c k

comment(s)?

How d i d y o u l i k e

the blended food?_

Like

© C.

t h e b l e n d e d f o o d a s I n d i c a t e d by e a g e r n e s s t o e a t t h e f o o d ?

O.K.

Did you c o n s i d e r the blended

Dislike

©

P u t an M X H I n one b l o c k

foods: Fair?

Good?

Poor?

Appearance_ Flavour Feel-1n-the-mouth Ease o f p r é p a r a t 1 o n _ D u r i n g t h e f o u r weeks t h e new f o o d was e a t e n , d i d : Increase?

Decrease?

Remain t h e same?

Appetite Flatulence_ Yom1 t i n g Diarrhea Undigested stool contents E.

What o t h e r f o o d s d i d y o u r c h i l d consume d u r i n g t h e f o u r weeks t h e f o o d s u p p l e m e n t was eaten?

F i g u r e 1. B l e n d e d f o o d q u e s t i o n n a i r e . (Reproduced w i t h p e r m i s s i o n from r e f e r e n c e 16. C o p y r i g h t 1983 U n i t e d N a t i o n s U.)

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k i l o g r a m q u a n t i t y of dry b l e n d , of the same sample number, was p r o v i d e d weekly f o r each of f o u r weeks f o r each c h i l d . At the end of the f o u r weeks, the n u t r i t i o n worker at each c l i n i c , using the C r e o l e t r a n s l a t i o n of the q u e s t i o n n a i r e d e s c r i b e d , recorded the response of each mother, and t h a t of her c h i l d , to the assigned blended food sample. The a u x i l i a r y n u t r i t i o n i s t a l s o recorded other foods consumed d u r i n g the t e s t i n t e r v a l , because the blended foods were meant t o supplement the r e g u l a r d i e t . Statistical Analysis. For each o f the 11 p o s s i b l e q u e s t i o n n a i r e responses Tor p r e f e r e n c e or g a s t r o i n t e s t i n a l e f f e c t , as shown in F i g u r e 1, value numbers were a s s i g n e d t o the d i f f e r e n t d e s c r i p t i v e responses. For the s e c t i o n on the c h i l d s eagerness t o eat and m o t h e r ' s o v e r a l l l i k i n g o f the f o o d , values of 1, 2 and 3 were assigned t o the responses L i k e , OK and D i s l i k e , r e s p e c t i v e l y . For the s e c t i o n on m o t h e r ' s o p i n i o n of food c h a r a c t e r i s t i c , values of 1, 2 and 3 were a s s i g n e d t o the responses Good, F a i r and Poor, respectively. For the section on mother's observation of g a s t r o i n t e s t i n a l e f f e c t s , v a l u e s o f 1, 2 and 3 were a s s i g n e d t o the responses I n c r e a s e , Remains the same, and Decrease, r e s p e c t i v e l y . In a d d i t i o n , f o r the purpose of s t a t i s t i c a l a n a l y s i s , the n u t r i t i o n center C h r i s t - R o i (69 C h i l d r e n ) was d e s i g n a t e d N o . l ; C a r r e f o u r F e u i l l e s (34 c h i l d r e n ) was No. 2 ; and the combined Delmas, P e r n i e r and S a l v a t i o n Army c e n t e r s (54 C h i l d r e n ) was No. 3. Several approaches were taken t o h a n d l i n g the d a t a by a n a l y s i s of variance (ANOYA) U8). In some cases, data from all participating c h i l d r e n were used in the analysis. In other i n s t a n c e s a h i e r a r c h a l design was employed t h a t used o n l y p a r t of the c o l l e c t e d d a t a . Combining the data from a l l the c l i n i c s , ANOYA was used to t e s t t h e 11 q u e s t i o n n a i r e responses f o r s t a t i s t i c a l s i g n i f i c a n c e of v a r i a t i o n s among the t h r e e n u t r i t i o n c e n t e r s , and between the two b l e n d t y p e s , and whether a d i f f e r e n c e between blends depended upon the n u t r i t i o n c e n t e r ( i n t e r a c t i o n e f f e c t ) . The same v a r i a t i o n s were examined s t a t i s t i c a l l y u s i n g o n l y the f i r s t c h i l d in each family. The r a t i o n a l e f o r this approach was t h a t d a t a from d i f f e r e n t c h i l d r e n of the same f a m i l y might be c o r r e l a t e d , because the same mother responded t o a l l the q u e s t i o n s . Several c i r c u m s t a n c e s developed d u r i n g the f i e l d t e s t t h a t n e c e s s i t a t e d r e p e a t i n g the ANOVA a f t e r c e r t a i n data were o m i t t e d . For a s e r i e s of samples, more than one c h i l d used the same sample number. T h i s problem is understandable in a s e t t i n g w i t h a high i n c i d e n c e of p r o t e i n - c a l o r i e m a l n u t r i t i o n ( 1 9 ) . There were a l s o a few c h i l d r e n in the study who were above tRë o r i g i n a l l y s e t upper age limit of five years. ANOYAs were made e x c l u d i n g both o b s e r v a t i o n s on c h i l d r e n s h a r i n g t h e same numbered sample and those on c h i l d r e n over f i v e y e a r s . In making these r e r u n s , a p p r o p r i a t e adjustments had to be made in some r e t a i n e d data because of changes in c h i l d - o r d e r within family and t o t a l number of c h i l d r e n in the f a m i l y p a r t i c i p a t i n g in t h e s t u d y . R e s u l t s and

Discussion

Composition and N u t r i t i o n a l Q u a l i t y . Comparisons o f MCSM a r e summarized in T a b l e s II through IY. Table

blends CC and II shows t h a t

12.

HAYES ET AL.

Corn-G landless Cottonseed Blended Food

145

there were some marked differences between blends in protein providing ingredients, but added o i l and f o r t i f i c a t i o n l e v e l s , except for lysine monohydrochloride were s i m i l a r . The compositions Table I I . Formulation of the f i e l d tested food blends corn-cottonseed (CC) and modified corn-soy-milk (MCSM).

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch012

Ingredient

Amount in Blend [%)

Cornmeal, processed, gelatinized Soy f l o u r , defatted, toasted Cottonseed f l o u r , glandless, defatted M i l k , nonfat dry Sucrose, granulated Soy o i l Cottonseed o i l Mineral premix Vitamin premix with antioxidants L-lysine HC1

CC

MCSM

52.5

45.4 22.9

—

31.5

—

15.0 8.0 5.9

—

8.0 —

5.1 2.7 O.1 O.09

—

2.7 O.1 —

of the mineral premix and vitamin premix with antioxidants are given in reference (3). The proximate analyses (Table III) are very s i m i l a r for both blends. The ingredient percentages and s i m i l a r proximate analyses of both blends aligned quite well with the s p e c i f i c a t i o n s previously described. The protein quality and c a l o r i c densities of the two blends are given in Table IV. Although there was a difference in the most l i m i t i n g amino acids between the blends, they were close in chemical score. The chemical score is the score of the most l i m i t i n g essential amino Table I I I . Proximate analyses of f i e l d tested food blends corn-cottonseed (CC) and modified corn-soy-milk (MCSM). Component Protein Lipids Crude f i b e r Ash Moisture Carbohydrate (by difference)

Amount in Blend {%)

CC

MCSM

20.7 6.3 O.9 4.8 8.7 58.6

20.8 6.5 1.0 5.3 8.8 57.6

acid. The amino acid scores were computed according to the d e f i n i t i o n in reference (j£Q). The two blends were not found to be statistically significantly different in PER, proportionally adjusted to reference c a s e i n , or in NPR. The blends were almost equal in c a l o r i c density, an important c h a r a c t e r i s t i c of weaning foods. O v e r a l l , the n u t r i t i o n a l values of both blends were very comparable .

PLANT PROTEINS

146

T a b l e IV. N u t r i t i o n a l q u a l i t y o f f i e l d t e s t e d food blends c o r n - c o t t o n s e e d (cc) and m o d i f i e d c o r n - s o y - m i l k (MCSM). Quality factor

Blend cc

Chemical score L i m i t i n g amino a c i d

(s)

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch012

PER(adjusted) + S.E. NPR+S.E. N i t r o g e n d i g e s t i b i l i t y {%) C a l o r i c d e n s i t y (Kcal/lOOg)

ÔÛ Threonine 2.12+O.05 3.62+O.07 87.7 374

MCSM 84 Methionine +cystine 2.26+O.06 3.72+O.05

85.6 372

A c c e p t a b i l i t y and T o l e r a n c e Responses. The r e s u l t s of s t a t i s t i c a l a n a l y s e s of the blended food q u e s t i o n n a i r e responses are p r e s e n t e d in Table Y. In t h i s t a b l e , t e s t i n g by a n a l y s i s of v a r i a n c e of b l e n d type d i f f e r e n c e is designated by BT, o f c l i n i c number d i f f e r e n c e by CN, and of the dependence of d i f f e r e n c e s between blends on c l i n i c number by CN-BT. Reference is now made t o the f i r s t v e r t i c a l s e t of r e s u l t s in T a b l e Y, encompassing a l l c l i n i c s and a l l c h i l d r e n . One hundred f i f t y seven c h i l d r e n were i n v o l v e d ; 77 used blend CC and 80, blend MCSM. I t is a p p a r e n t , the mean scores n e a r l y equal t o one, t h a t both blends were very a c c e p t a b l e t o both c h i l d r e n and mothers. D e s p i t e the f a c t t h a t blend CC had a s l i g h t l y green c a s t due to i t s c o t t o n s e e d f l o u r component, c o l o r d i f f e r e n c e between blends d i d not affect the mothers' comparative appearance acceptability. Appearance and f l a v o r of both blends r e c e i v e d the h i g h e s t p o s s i b l e a c c e p t a b i l i t y r a t i n g by the mothers. They had a s i g n i f i c a n t l y h i g h e r p r e f e r e n c e (p Q. i_ i_ . γ- Ο (Ο Ο Ο (Ο Ο I Φ φ > ι— φ CO C0 Ο . (0 Φ C0 -

Co-

•σ ι— •r4=

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α.r— Φ

VO

00

ο

Ο : Ε

CO ι— C Φ r— Ο Φ

•Ή

ο

ο

φ CΦJ-

r— Ο Ο

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C •r— Ο

Φ +->

ο c φ

4Φ-> α. ο.
Ο

Ο Σ s:

American Chemical Society Library 1155 16th St., N.W. Washington, D.C.

20036

+->

Ό Φ

σχΰ +J C Φ C O •ι- χ: Φ 4-> s- σ> •r- S- -rΕ «0 Ό Ο τ- C >- Q =5

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were consuming e i t h e r b l e n d . Mothers a t c l i n i c number 2 a l s o more o f t e n noted i n c r e a s e d f l a t u l e n c e when e i t h e r b l e n d was consumed. However, in t h e case o f both a p p e t i t e and f l a t u l e n c e , s i g n i f i c a n t d i f f e r e n c e s between the two blends at c l i n i c number 2 c o u l d not be found. Table V a l s o d e c r i b e s r e s u l t s o f analyses of v a r i a n c e t h a t were performed when d a t a f o r u n q u a l i f i e d c h i l d r e n were removed. The data f o r 42 c h i l d r e n were excluded from the t o t a l o f 157, because of s h a r i n g food having the same sample number. The d a t a f o r 7 c h i l d r e n , age 6 and o l d e r , were a l s o e x c l u d e d . When data in both t h e s e c a t e g o r i e s were e x c l u d e d , s i g n i f i c a n t d i f f e r e n c e s were not found between the two blends f o r any of the 11 q u e s t i o n n a i r e responses, i n c l u d i n g f e e l - i n - t h e - m o u t h . Perhaps, because o f fewer o b s e r v a t i o n s , a s i g n i f i c a n t d i f f e r e n c e between blends was not found f o r t h i s c h a r a c t e r i s t i c when u n q u a l i f i e d c h i l d r e n were e x c l u d e d from the t o t a l . As in the case when a l l c h i l d r e n ' s responses were i n c l u d e d in t h e a n a l y s i s , s t a t i s t i c a l l y h i g h l y s i g n i f i c a n t ( ζ

oo

19.

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239

v i a s e l e c t i o n . S e l e c t i o n f o r h i g h p r o t e i n c u l t i v a r s which are r e l a t i v e l y i n s e n s i t i v e t o e n v i r o n m e n t a l d i f f e r e n c e s and o p t i m i z a t i o n of c u l t u r a l p r a c t i c e s a r e a l s o a t t r a c t i v e r e s e a r c h areas f o r i n c r e a s i n g p r o t e i n content.

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Nutritional

Value

Feeding Studies. A l t h o u g h sweet p o t a t o e s a r e a s i g n i f i c a n t s o u r c e of c a l o r i e s in many p a r t s o f the w o r l d , v e r y l i t t l e i n f o r m a t i o n is a v a i l a b l e c o n c e r n i n g the n u t r i t i o n a l q u a l i t y o f sweet p o t a t o p r o t e i n as d e t e r m i n e d by c o n t r o l l e d f e e d i n g s t u d i e s in humans. T h i s is in s t r i k i n g c o n t r a s t t o numerous r e p o r t e d s t u d i e s on the f e e d i n g o f w h i t e p o t a t o e s t o humans (30). An e a r l y s t u d y in which the sweet p o t a t o was used as the s o l e s o u r c e of n i t r o g e n in the d i e t o f humans was t h a t o f A d o l p h and L i u (31). They r e p o r t e d t h a t n i t r o g e n b a l a n c e c o u l d be m a i n t a i n e d w i t h sweet p o t a t o n i t r o g e n p r o v i d e d s u f f i c i e n t amounts were consumed. R e s e a r c h by o t h e r workers (32, 33) a l s o suggested t h e sweet p o t a t o p r o t e i n is r e a d i l y u t i l i z e d by humans. Large amounts o f sweet p o t a t o must be e a t e n t o p r o v i d e enough n i t r o g e n . Oomen (34) r e p o r t e d t h a t in New Guinea, where 80-90% o f t h e t o t a l c a l o r i e s were o b t a i n e d from sweet p o t a t o , the s u b j e c t s s t u d i e d were u s u a l l y in s i g n i f i c a n t n e g a t i v e n i t r o g e n b a l a n c e . S i n c e n e g a t i v e n i t r o g e n s t a t u s means c o n t i n u o u s breakdown o f body p r o t e i n l e a d i n g t o s e r i o u s m a l n u t r i t i o n , Oomen (34) was p u z z l e d because the s u b j e c t s seemed t o be in good h e a l t h . As a r e s u l t , he s u g g e s t e d t h a t e a t i n g l a r g e amounts o f sweet p o t a t o might i n d u c e an i n t e s t i n a l m i c r o f l o r a which was a b l e t o f i x gaseous n i t r o g e n so t h a t i t c o u l d be u t i l i z e d t o s y n t h e s i z e amino a c i d s . O b v i o u s l y , i f such were the case, much of the knowledge o f p r o t e i n n u t r i t i o n would be in doubt s i n c e the v a l i d i t y o f n i t r o g e n b a l a n c e s t u d i e s upon which most o f t h i s knowledge is based would be in doubt. A l a t e r study (_35) u s i n g c a r e f u l l y c o n t r o l l e d c o n d i t i o n s i n d i c a t e d t h a t b o t h a d o l e s c e n t and young a d u l t males m a i n t a i n e d in s l i g h t l y n e g a t i v e n i t r o g e n b a l a n c e t h r o u g h use o f sweet p o t a t o as the major n i t r o g e n s o u r c e d e v e l o p e d c l i n i c a l symptoms o f m i l d p r o t e i n m a l n u t r i t i o n . These i n c l u d e d abnormal plasma f r e e amino a c i d p a t t e r n s and a d e c r e a s e in p h y s i c a l s t a m i n a . In a d d i t i o n , no e v i d e n c e o f in v i v o n i t r o g e n f i x a t i o n c o u l d be d e t e c t e d in f e c a l m a t e r i a l , i n d i c a t i n g t h a t the m i c r o f l o r a i n d u c e d by l o n g - t e r m consumption o f sweet p o t a t o e s a r e not c a p a b l e of f i x i n g n i t r o g e n . The r e p o r t t h a t h a b i t u a l sweet p o t a t o e a t e r s are somewhat independent o f d i e t a r y n i t r o g e n appears t o have no b a s i s in f a c t . R e s u l t s r e p o r t e d by Huang e t a l . (35) i n d i c a t e d t h a t w i t h t e e n a g e r s a p o s i t i v e n i t r o g e n b a l a n c e c o u l d be m a i n t a i n e d w i t h an i n t a k e of O.67 t o O.71 g p r o t e i n / k g body weight, where the sweet p o t a t o f u r n i s h e d most o f the p r o t e i n . The energy r e q u i r e m e n t f o r t h i s l e v e l of p r o t e i n consumption was 54 k c a l / k g body weight. The a p p a r e n t p r o t e i n d i g e s t i b i l i t y was found t o be 66%, which was v e r y c l o s e t o a p r e v i o u s l y r e p o r t e d v a l u e of 67% (36). The above r e p o r t s , a l t h o u g h l i m i t e d in number, i n d i c a t e t h a t sweet p o t a t o p r o t e i n is o f good n u t r i t i o n a l q u a l i t y but the q u a n t i t y is low in the c u l t i v a r s used. The c u l t i v a r T a i n o n 57 used by

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Huang e t a l . (35) had a crude p r o t e i n c o n t e n t o f from O.8 t o 1.3% ( f r e s h w e i g h t ) . A r e p o r t by B r e s s a n i e t a l . (3_7) , which e v a l u a t e d t h e n u t r i t i o n a l v a l u e o f d i e t s based on s t a r c h y foods and beans, i n d i c a t e d t h a t f o r t h e r a t , sweet p o t a t o p r o t e i n was o f poor n u t r i t i o n a l q u a l i t y . When m e t h i o n i n e was added t o a l l d i e t s t o r a i s e s u l f u r amino a c i d s , sweet p o t a t o s t i l l r e q u i r e d t h e l a r g e s t amount o f s u p p l e m e n t a t i o n w i t h bean f l o u r t o m a i n t a i n animal weight (Table I I ) . Sweet p o t a t o f l o u r c o n t a i n e d 3.8% p r o t e i n , t h e second h i g h e s t amount o f p r o t e i n among s t a r c h y f o o d s , and y e t t h e p r o t e i n appeared t o be t h e p o o r e s t in n u t r i t i o n a l q u a l i t y . However, i t s h o u l d be noted t h a t t h e sweet p o t a t o e s used in t h i s study were d r i e d a t 60 C b u t were n o t cooked. Uncooked sweet p o t a t o s t a r c h is not c o m p l e t e l y d i g e s t a b l e by r o d e n t s . As a consequence, maintenance r e q u i r e m e n t s would i n c r e a s e . T h i s is t h e most l i k e l y e x p l a n a t i o n f o r t h e i n c r e a s e d requirement f o r bean f l o u r , b u t t h e r e a l s o may have been i n t e r f e r e n c e w i t h d i g e s t i o n from p r o t e a s e i n h i b i t o r s p r e s e n t in uncooked sweet p o t a t o e s . W a l t e r e t a l . (38) measured t h e p r o t e i n e f f i c i e n c y r a t i o (PER) o f f l o u r p r e p a r e d from sweet p o t a t o e s which were cooked in a d r y i n g oven. Because t h e PER is determined on t h e b a s i s o f a d i e t c o n t a i n i n g 10% p r o t e i n , t h e 'Jewel' and ' C e n t e n n i a l ' sweet p o t a t o e s used in t h i s s t u d y were s t o r e d u n t i l s u f f i c i e n t s t a r c h had m e t a b o l i z e d t o i n c r e a s e crude p r o t e i n c o n t e n t t o 11.25% (dry b a s i s ) . When t h e f l o u r was f e d t o Sprague-Dawley s t r a i n r a t s , t h e c o r r e c t e d PER v a l u e s were 2.22 and 2.00 f o r ' C e n t e n n i a l ' and 'Jewel' c u l t i v a r s , r e s p e c t i v e l y , compared t o 2.50 f o r c a s e i n . ' C e n t e n n i a l ' had t h e h i g h e s t PER v a l u e o f t h e two c u l t i v a r s because i t s NPN c o n t e n t was lower. The n e t e f f e c t o f i n c r e a s e d NPN c o n t e n t is t o lower t h e amount o f e s s e n t i a l amino a c i d s as a p e r c e n t a g e o f t h e t o t a l n i t r o g e n and thus d e c r e a s e t h e PER value. A n t i - n u t r i t i o n a l Factors I t has been r e c o g n i z e d s i n c e 1954 (39) t h a t sweet p o t a t o c o n t a i n s t r y p s i n i n h i b i t o r s . T r y p s i n i n h i b i t o r s (TI) have an a n t i n u t r i t i o n a l e f f e c t by i n h i b i t i n g p r o t e o l y t i c a c t i o n o f t r y p s i n d u r i n g d i g e s t i o n . S i n c e t h e i n i t i a l r e p o r t , T I a c t i v i t y in sweet p o t a t o e s has been t h e s u b j e c t o f s e v e r a l r e p o r t s . D i c k e y and C o l l i n s (40) r e p o r t e d t h e p r e s e n c e o f 7 T I bands in t h e 4 c u l t i v a r s examined, t h e i n t e n s i t y o f t h e bands b e i n g c u l t i v a r dependent. Heat i n a c t i v a t i o n o f T I a l s o was c u l t i v a r dependent, but h e a t i n g t h e t i s s u e t o 94 C., f o l l o w e d by c o o l i n g t o room temperature d e s t r o y e d 93-97% o f t h e a c t i v i t y in a l l c u l t i v a r s . C o n s e q u e n t l y , c o o k i n g o f sweet p o t a t o e s s h o u l d e l i m i n a t e most of the a n t i - n u t r i t i o n a l e f f e c t . E n t e r i t i s n e c r o t i a n s (EN), a spontaneous form o f e n t e r i c gangrene endemic t o t h e h i g h l a n d s o f Papua, New Guinea, is caused by t o x i n s produced when C l o s t r i d i u m p e r f r i n g e n s o f t h e g u t e n t e r a r a p i d growth phase (41). I t has been p o s t u l a t e d t h a t t h e d i s e a s e o c c u r s in p o p u l a t i o n s which consume a low p r o t e i n d i e t , e.g., sweet p o t a t o as t h e s t a p l e f o o d combined w i t h T I a c t i v i t y which

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T a b l e I I . E f f e c t o f S u p p l e m e n t a t i o n o f Starchy^ Foods With Common Beans on Weight Maintenance

Flours Cassava Plantain Potato Sweet P o t a t o Bean

% Crude Protein 1..4 3,.1 9..5 3..8 22..8

% Bean F l o u r for Nitrogen

Required Balance

14,.5 20..1 14..6 29..3 10..1°

^From B r e s s a n i e t a l . (37) . W i s t a r r a t s were t e s t a n i m a l . D Supplemented w i t h m e t h i o n i n e . C o r n s t a r c h used as s t a r c h y f o o d w i t h bean f l o u r .

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e f f e c t i v e l y reduces the p r o t e o l y t i c c a p a c i t y of the d i g e s t i v e system t o such a degree t h a t i t cannot d e s t r o y t h e p r o t e i n a c e o u s t o x i n by h y d r o l y s i s . A r e p o r t by Bradbury e t a l . (13) i n d i c a t e d t h a t t h e r e was no c o r r e l a t i o n between t h e i n c i d e n c e o f EN in a g i v e n r e g i o n and t h e amount o f T I a c t i v i t y in t h e sweet p o t a t o c u l t i v a r s consumed in t h a t r e g i o n . U n l e s s t h e p o p u l a t i o n s i n v o l v e d consume l a r g e amounts o f raw sweet p o t a t o e s , i t is h i g h l y u n l i k e l y t h a t t h e T I is o b t a i n e d from t h i s s o u r c e s i n c e c o o k i n g has been shown t o i n a c t i v a t e t h e i n h i b i t o r (40, 4 2 ) .

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Amino A c i d

Composition

In r e c e n t y e a r s , a number o f workers have p u b l i s h e d amino a c i d a n a l y s e s o f t h e sweet p o t a t o (38, 43, 13, 22, 1 8 ) . The o v e r a l l p i c t u r e is t h a t t h e sweet p o t a t o amino a c i d p a t t e r n is o f good n u t r i t i o n a l q u a l i t y but t h a t t h e v a r i a b i l i t y o f i n d i v i d u a l amino a c i d s b o t h w i t h i n t h e same c u l t i v a r and a c r o s s c u l t i v a r s is v e r y h i g h . F o r example, W a l t e r e t a l . (44) r e p o r t e d t h a t w i t h t h e e x c e p t i o n o f a r o m a t i c amino a c i d s , every e s s e n t i a l amino a c i d has a s c o r e o f l e s s than 100 in one o r more c u l t i v a r s . The amino a c i d s c o r e is d e f i n e d as t h e g o f amino a c i d in 100 g o f t e s t p r o t e i n d i v i d e d by t h e number o f g o f t h a t amino a c i d in the FAO/WHO r e f e r e n c e p a t t e r n t i m e s 100. Bradbury e t a l . (22) showed t h a t , f o r t h e same c u l t i v a r , e n v i r o n m e n t a l e f f e c t s on t h e amino a c i d p a t t e r n s is s i g n i f i c a n t . F o r t h r e e c u l t i v a r s , they found a mean p e r c e n t s t a n d a r d d e v i a t i o n f o r a l l amino a c i d s o f 24.2, 23.4 and 20.6 o v e r 5 environments. From t h e i r r e s u l t s , Bradbury (22) c o n c l u d e d t h a t in t h e h i g h l a n d s o f Papua, New G u i n e a , t h e EAA most l i k e l y t o be l i m i t i n g in d e c r e a s i n g o r d e r o f p r o b a b i l i t y were l y s i n e , l e u c i n e and s u l f u r amino a c i d s . These workers s u g g e s t e d t h a t a p a r t o f t h e l a r g e d i f f e r e n c e r e p o r t e d worldwide in the r e l a t i v e amount o f s u l f u r amino a c i d s may be due in p a r t t o d i f f i c u l t i e s in t h e a n a l y s i s o f t h e s e compounds. C o n c e n t r a t e s and I s o l a t e s The l i t e r a t u r e on c o n c e n t r a t e d sweet p o t a t o p r o t e i n is s p a r s e . Amino a c i d p a t t e r n s f o r sweet p o t a t o p r o t e i n i s o l a t e s have been r e p o r t e d by t h r e e groups (16, 45, 4 6 ) . One r e p o r t showed t h a t when compared t o t h e FAO s t a n d a r d (47), no amino a c i d s were l i m i t i n g . The o t h e r r e p o r t s showed t o t a l s u l f u r amino a c i d s and l y s i n e t o be l i m i t i n g (Table I I I ) . The p a t t e r n s i n d i c a t e a n u t r i t i o n a l l y w e l l b a l a n c e d p r o t e i n . The improvement in n u t r i t i o n a l q u a l i t y , when compared t o amino a c i d p a t t e r n s from whole sweet p o t a t o , is due t o t h e f a c t t h a t whole sweet p o t a t o e s c o n t a i n s u b s t a n t i a l amounts o f NPN, which c o n s i s t s m a i n l y o f n o n e s s e n t i a l amino a c i d s . T h i s e f f e c t i v e l y d i l u t e s t h e EAA and lowers t h e amino a c i d s c o r e . F e e d i n g s t u d i e s w i t h t h e r a t as the t e s t a n i m a l v e r i f i e d the h i g h n u t r i t i o n a l q u a l i t y i n d i c a t e d by t h e amino a c i d p a t t e r n (45). U s i n g i s o l a t e s and c o n c e n t r a t e s p r e p a r e d from 'Jewel' and ' C e n t e n n i a l ' c u l t i v a r s , PER v a l u e s were e q u a l t o t h a t o f c a s e i n (milk p r o t e i n ) (Table I V ) . E x a m i n a t i o n o f t h e amino a c i d p a t t e r n s o f sweet p o t a t o p r o t e i n and c a s e i n r e v e a l e d t h a t b o t h c o n t a i n e d

19.

WALTER AND PURCELL

243

Protein of the Sweet Potato

T a b l e I I I . Amino A c i d C o m p o s i t i o n o f P r o t e i n I s o l a t e s A c i d P e r 100 g o f P r o t e i n )

(g o f Amino

W a l t e r and Purcell Nagase FAO/WHO C a t i g n a n i (45) e t a l . ( 1 6 ) (46) (47) 3

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Essential Threonine Valine Methionine Total Sulfur Isoleucine Leucine Tyrosine Phenylalanine Lysine Tryptophan ^ ^ Amino A c i d S c o r e ' Total Sulfur Lysine

6.,4 7.,9 2..0 3..1 5..6 7..4 6..9 8..2 5..2 1..2° 88 95

5.,5 6..8 2..6 3..0 5..3 7..8 5..2 6..7 6..8 1.. i c c

4.6 7.9 2.5 4.1 5.3 8.7 3.6 6.0 6.5 1.8 c

4..0 5..0 3..5 4..0 7..0

5,.5 1,.0

100 100

86 100

Nonessential Aspartic Acid Serine Glutamic A c i d Proline Glycine Alanine Histidine N H

3 Arginine

18,.9 6,.6 9,.6 4,.2 5,.3 5,.4 2,.7 1..6 5,.9

14,.4 5,.1 8,.6 5,.4 4,.3 4,.6 2 •f

13.1 5.5 11.8 4.3 2.6 6.1

6 .0

6.4

-L

"'Jewel' c u l t i v a r . C u l t i v a r unknown. T r y p t o p h a n c o n t e n t measured c o l o r i m e t r i c a l l y on enzyme-hydrolyzed ^material. g o f amino a c i d in 100 g o f t e s t p r o t e i n / g o f amino a c i d in FAO/WHO r e f e r e n c e p a t t e r n χ 100. ^ A l l o t h e r e s s e n t i a l amino a c i d s exceeded FAO/WHO v a l u e s . NH not reported. From W a l t e r e t a l . (44).

Fractions

2.78 + 2.73 + 2.78 +

2.81 + 2.91 + 2.96 +

PER

O.10 O.09 O.10

O.11 O.10 O.07

Wt. Gained, g

2.50 + O.09 109.5 + 7.8 2.47 + O.09 117.6 + 11.3 2.50 + O.10 122.2 + 14.9

394.0 + 25.3 431.1 + 39.5 437.9 + 44.5

477.9 + 37.7 477.1 + 29.0 472.6 + 35.3

Food Consumed, g

b

71.6 + 2.9 71.1 + 2.7 71.3 + 2.7

78.3 + 3.1 78.3 + 3.3 78.4 + 3.2

Initial Group wt., g

f o r P r o t e i n F r a c t i o n s From Sweet P o t a t o e s

2.50 + O.09 134.3 + 11.7 2.64 + O.09 138.9 + 11.7 2.63 + O.07 140.3 + 12.4

Corrected PER

(PER)

Mean and s t a n d a r d d e v i a t i o n c a l c u l a t e d from d a t a from 10 r a t s p e r d i e t group. C o r r e c t e d by a d j u s t i n g t e s t d i e t s t o 2.50 f o r c a s e i n (AOAC). From W a l t e r and C a t i g n a n i ( 4 5 ) .

Casein 'Jewel' 'Centennial'

Chromoplast

Casein 'Jewel' 'Centennial'

White

Protein

T a b l e IV. P r o t e i n E f f i c i e n c y R a t i o

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch019

m in

73 Ο Η

-α

> Ζ Η

19. WALTER AND PURCELL

Protein of the Sweet Potato

245

l e s s s u l f u r amino a c i d s than r e q u i r e d f o r r a t growth. In a d d i t i o n , sweet p o t a t o c o n t a i n e d l e s s l y s i n e , w h i l e c a s e i n c o n t a i n e d l e s s t h r e o n i n e t h a n is r e q u i r e d f o r r a t growth. A p p a r e n t l y t h e o v e r a l l d e f i c i e n c i e s l i m i t e d r a t growth about the same amount. The end r e s u l t was t h a t r a t s f e d e i t h e r p r o t e i n grew a t about the same rate. Horigome e t a l . (15) r e p o r t e d a PER o f 1.9 f o r p r o t e i n r e c o v e r e d from an i n d u s t r i a l sweet p o t a t o s t a r c h f a c i l i t y . They were a b l e t o i n c r e a s e t h e PER t o 2.5 by supplementing the d i e t s w i t h l y s i n e and m e t h i o n i n e . A p o r t i o n o f t h e s e amino a c i d s were e i t h e r d e s t r o y e d o r made b i o l o g i c a l l y n o n a v a i l a b l e by t h e p r o c e s s i n g o p e r a t i o n . The p o s s i b i l i t y a l s o e x i s t s t h a t t h e s e amino a c i d s were l i m i t i n g in t h e c u l t i v a r s s t u d i e d .

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch019

E f f e c t o f P r o c e s s i n g on N u t r i t i o n a l

Quality

Heat p r o c e s s i n g o f sweet p o t a t o e s can have d e l e t e r i o u s e f f e c t s on p r o t e i n n u t r i t i o n a l q u a l i t y . P u r c e l l and W a l t e r (48) found t h a t the i n t e n s i t y o f t h e h e a t p r o c e s s i n g c o n d i t i o n s had a d i r e c t b e a r i n g on n u t r i t i o n a l q u a l i t y o f the p r o t e i n . In t h i s study l y s i n e was d e s t r o y e d , presumably v i a i r r e v e r s i b l e r e a c t i o n w i t h r e d u c i n g s u g a r s (40). Both s u c r o s e syrup-canned sweet p o t a t o e s and drum-dried sweet p o t a t o f l a k e s c o n t a i n e d 26% l e s s l y s i n e than d i d baked sweet p o t a t o e s . In a d d i t i o n , syrup-canned sweet p o t a t o e s c o n t a i n e d 25% l e s s t o t a l n i t r o g e n than d i d e i t h e r baked o r drum-dried sweet p o t a t o e s . T h i s l o s s o f n i t r o g e n was a p p a r e n t l y due t o s o l u t i o n o f the NPN f r a c t i o n in t h e s y r u p . Other r e p o r t s on canned sweet p o t a t o e s r e v e a l s i m i l a r changes. Canned sweet p o t a t o e s from v a r i o u s l o c a t i o n s were found t o c o n t a i n 3.8 t o 4.2% (dry b a s i s ) crude p r o t e i n (_50) , r a t h e r t h a n the e x p e c t e d 4.5-7.0%. A l t h o u g h no mention was made of the l o w e r - t h a n - e x p e c t e d crude p r o t e i n v a l u e s , t h e s e were p r o b a b l y due t o d i s s o l u t i o n o f p a r t o f t h e NPN f r a c t i o n in the s y r u p . S i m i l a r l y , M e r e d i t h and D u l l (43) r e p o r t e d t h a t c a n n e d - i n - s y r u p sweet p o t a t o e s c o n t a i n e d c a . 45% l e s s amino a c i d s t h a n d i d t h e r o o t s b e f o r e p r o c e s s i n g . S i n c e s y r u p is d i s c a r d e d b e f o r e t h e canned r o o t s a r e e a t e n , t h i s r e s u l t s in a s e r i o u s l o s s o f n i t r o g e n . The s e v e r i t y o f h e a t t r e a t m e n t d u r i n g d e h y d r a t i o n has a s i g n i f i c a n t e f f e c t on p r o t e i n n u t r i t i o n a l q u a l i t y . Cooked sweet p o t a t o e s d e h y d r a t e d in a f o r c e d - d r a f t oven a t 60 C had a PER o f 2.2, w h i l e a second l o t o f cooked sweet p o t a t o e s d e h y d r a t e d on a steam-heated drum d r y e r had a PER o f 1.3 (38). The l y s i n e c o n t e n t measured by a c i d h y d r o l y s i s - i o n exchange chromatography was somewhat lower in t h e drum d e h y d r a t e d f l o u r but not s u f f i c i e n t l y low t o a c c o u n t f o r the d i f f e r e n c e in PER v a l u e s . F u r t h e r s t u d y u s i n g an a s s a y f o r a v a i l a b l e l y s i n e (SI) showed t h a t a l a r g e p a r t o f t h e l y s i n e was n o t a v a i l a b l e . Thus, a c i d h y d r o l y s i s can l i b e r a t e b i o l o g i c a l l y n o n a v a i l a b l e l y s i n e which is s u b s e q u e n t l y q u a n t i f i e d a l o n g w i t h a v a i l a b l e l y s i n e , c a u s i n g an o v e r e s t i m a t i o n o f t h e n u t r i t i o n a l q u a l i t y o f t h e f o o d . T h i s is most l i k e l y t o happen when h i g h l e v e l s o f r e d u c i n g sugars a r e p r e s e n t in t h e f o o d and l y s i n e is l i m i t i n g , as is the case w i t h sweet p o t a t o e s .

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Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch019

Summary and

Conclusions

The sweet p o t a t o ranks s i x t h in average p r o d u c t i o n among the major f o o d c r o p s o f the w o r l d . There is s i g n i f i c a n t p o t e n t i a l f o r i n c r e a s i n g t h e p r o t e i n c o n t e n t o f t h i s c r o p by a c o m b i n a t i o n o f b r e e d i n g / s e l e c t i o n and o p t i m i z a t i o n o f p r o d u c t i o n p r a c t i c e s . A c c o r d i n g t o p r e s e n t knowledge, most o f t h e n i t r o g e n of the sweet p o t a t o is in a form s u i t a b l e t o s a t i s f y human n i t r o g e n r e q u i r e m e n t s . The p r o t e i n component comprises from 60-85% o f the n i t r o g e n w i t h the remainder c o n s i s t i n g o f amino o r amide n i t r o g e n . The amino a c i d p a t t e r n o f the sweet p o t a t o is h i g h l y v a r i a b l e . I s o l a t e d sweet p o t a t o p r o t e i n is o f s u f f i c i e n t n u t r i t i o n a l q u a l i t y t o s u p p o r t growth o f l a b o r a t o r y r a t s t o the same e x t e n t as c a s e i n . Humans have been m a i n t a i n e d in n i t r o g e n b a l a n c e u s i n g sweet p o t a t o as t h e major s o u r c e o f p r o t e i n . P r o c e s s i n g o f sweet p o t a t o e s can have adverse e f f e c t s on the p r o t e i n n u t r i t i o n a l v a l u e . Canning sweet p o t a t o e s in a l i q u i d medium causes l e a c h i n g o f s o l u b l e n i t r o g e n o u s compounds i n t o t h e l i q u i d , t h e r e b y l o w e r i n g t h e n i t r o g e n c o n t e n t . Heat p r o c e s s i n g o f the sweet p o t a t o causes a d e c r e a s e in the b i o l o g i c a l a v a i l a b i l i t y o f l y s i n e . The e x t e n t o f the d e c r e a s e in l y s i n e a v a i l a b i l i t y is dependent upon the s e v e r i t y o f the heat t r e a t m e n t and t h e amount o f r e d u c i n g s u g a r s p r e s e n t d u r i n g h e a t i n g . Acknowledgments Paper no. 10141 o f t h e J o u r n a l S e r i e s o f the N o r t h C a r o l i n a A g r i c u l t u r a l Research S e r v i c e , R a l e i g h , NC 27695-7601. M e n t i o n o f a trademark o r p r o p r i e t a r y p r o d u c t does not c o n s t i t u t e a g u a r a n t e e o r warranty o f the p r o d u c t by the U. S. Department o f A g r i c u l t u r e o r N o r t h C a r o l i n a A g r i c u l t u r a l Research S e r v i c e , nor does i t imply a p p r o v a l t o the e x c l u s i o n o f o t h e r p r o d u c t s t h a t may be s u i t a b l e .

Literature Cited 1. "Production Yearbook," FAO, 1977, Rome, Italy. 2. "Recommended Daily Allowances," Food and Nutrition Board, National Academy of Sciences, National Research Council, 1980, Washington, DC. 3. Watt, Β. K.; Merrill, A. L. "Composition of Foods," 1975, U. S. Department of Agriculture Handbook No. 8. 4. USDA. Economics and Statistics Service, 1980, Statistical Bulletin No. 645. 5. Hipsley, Ε. H.; Kirk, Ν. Ε. Technical paper, 1965, South Pacific Commission, New Calonia, No. 147. 6. Purcell, A. E.; Walter, W. M., Jr. J. Agric. Food Chem. 1980, 28, 842. 7. Dickey, L. F.; Collins, W. W.; Young, C. T.; Walter, W. Μ., Jr. Hortscience, 1984, 19, 689. 8. Purcell, A. E.; Walter, W. Μ., Jr.; Giesbrecht, F. G. J. Amer. Soc. Hort. Sci. 1978, 103, 190. 9. Sober, H. A. "CRO Handbook of Biochemistry. Selected Data for Molecular Biology"; Chemical Rubber Co.: Cleveland, OH, 1970; pp. 1394-1395.

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19.

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247

10. Jones, D. B.; Gersdorff, C. E. F. J. Biol. Chem. 1931, 93, 119. 11. L i , He-S.; Oba, K. Agric. Biol. Chem. 1985, 49, 737. 12. Purcell, A. E.; Walter, W. Μ., Jr.; Giesbrecht, F. G. J. Agric. Food Chem. 1976, 24, 64. 13. Bradbury, J. H.; Baines, J.; Hammer, B.; Anders, M.; Millar, J. S. J. Agric. Food Chem. 1984, 32, 469. 14. Purcell, A. E.; Walter, W. Μ., Jr.; Giesbrecht, F. G. J. Agric. Food Chem. 1978, 26, 699. 15. Horigome, T.; Nakayama, N.; Ikeda, M. Chem. Abstr. 1972, 77, 661N. 16. Purcell, A. E.; Swaisgood, H. E.; Pope, D. T. J. Amer. Soc. Hort. Sci. 1972, 97, 30. 17. L i , L. J. Agric. Assoc. China 1974, 88, 17. 18. Goodbody, S. Trop. Agric. (Trinidad) 1984, 61, 20. 19. L i , L. J. Agric. Assoc. China 1977, 100, 78. 20. Purcell, A. E.; Walter, W. Μ., Jr.; Giesbrecht, F. G. J. Agric. Food Chem. 1978, 26, 362. 21. Collins, W. W.; Walter, W. M., Jr. "Sweet Potato: Proceedings of the First International Symposium"; Villareal, R. L.; Griggs, T. D., eds., Asian Vegetable Research and Development Center, Shanhua, Taiwan, China, 1982, p. 355. 22. Bradbury, J. H.; Hammer, B.; Hguyen, T.; Anders, M.; Miller, J. S. J. Agric. Food Chem. 1985, 33, 281. 23. Purcell, A. E.; Walter, W. Μ., Jr.; Nicholaides,J.J.; Collins, W. W.; Chancy, H. J. Amer. Soc. Hort. Sci. 1922, 107, 425. 24. Constantin, R. J.; Jones, L. G.; Hammett, H. L.; Hernandez, T. P.; Kahlich, C. G. J. Amer. Soc. Hort. Sci. 1984, 105, 610. 25. Kimber, A. J. Papua New Guinea Food Crops Conference Proceedings, Dept. Prim. Indus., Wilson, K.; Bourke, R. Μ., eds., Port Moresby, New Guinea, 1975, p. 63. 26. L i , L. J. Agric. Assoc. China 1975, 92. 27. Yeh, T. P.; Chen, Y. T.; Sun, C. C. J. Agric. Assoc. China 1981, 113, 33. 28. Purcell, A. E.; Pope, D. T.; Walter, W. Μ., Jr. Hortscience, 1976, 11, 31. 29. Constantine, R. J.; Hernandez, T. P.; Jones, L. G. J. Amer. Soc. Hort. Sci. 1974, 99, 308. 30. Knorr, D. Lebensm. -Wiss. Technol. 1978, 11, 109. 31. Adolph, W. H.; Liu, H. C. Chin. Med. J. 1939, 55, 337. 32. Kao, H. C.; Adolph, W. H.; Liu, H. C. Chin. J. Physiol. 1935, 9, 141. 33. Ruinard, J. Proc. Int. Symp. Tropical Crops 1967, 1, 89. 34. Oomen, H. A. P. C. Proc. Nutr. Soc. 1970, 29, 197. 35. Huang, P. C.; Lee, Ν. Y.; Chen, S. H. Amer. J. Clin. Nutr. 1979, 32, 1741. 36. Kandatsu, M. In "Food Chemistry"; Koseikan, Tokyo, 1964, p. 108. 37. Bressani, R.; Navarrete, D. A.; Elias, L. G. Qual. Plant Plant Foods Human Nutr. 1984, 34, 109. 38. Walter, W. Μ., Jr.; Catignani, G. L.; Yow, L. L.; Porter, D. H. J. Agric. Food Chem. 1983, 31, 947.

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39. Sohonie, K.; Bhandarker, A. P. J. Sci. Ind. Res. 1954, 13B, 500. 40. Dickey, L. F.; Collins, W. W. J. Amer. Soc. Hort. Sci. 1984, 109, 750. 41. Murrell, T. G. C. Chin. Med. J. 1982, 95, 843. 42. Obidairo, T. K.; Akpochago, Ο. M. Enzyme Microbiol. Technol. 1984, 6, 132. 43. Meredith, F. I.; Dull, G. G. Food Technol. 1979, 33, 55. 44. Walter, W. M., Jr.; Collins, W. W.; Purcell, A. E.J.Agric. Food Chem. 1984, 32, 695. 45. Walter, W. Μ., Jr.; Catignani, G. L.J.Agric. Food Chem. 1981, 29, 797. 46. Nagase, T. Fukuoka Igaku Zasshi, 1957, 48, 1828. 47. FAO/WHO. W.H.O. Tech. Rep. Ser. 1973, 522. 48. Purcell, A. E.; Walter, W. M., Jr. J. Agric. Food Chem. 1982, 30, 443. 49. Carpenter, K. J. Nutr. Abstr. Rev. 1973, 43, 404. 50. Collins, J. L. Tenn. Farm Home Sci. 1981, Jan.-Mar., 25. 51. Goodno, C.C.;Swaisgood, H. E.; Catignani, G. L. Anal. Biochem. 1981, 115, 203. RECEIVED December 26, 1985

20 Cucurbit Seed Protein and Oil T. J. Jacks

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch020

Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, New Orleans, LA 70179

Research concerning the structure, composition, and usefulness of cucurbit seeds (gourds, melons, squash, etc.) is reviewed. Cytological features are typical of those for oilseeds. Compositionally, decorticated seeds contain by weight 50% oil and 35% protein. The oil is unsaturated and edible; however, certain species contain conjuated trienoic fatty acids (drying oils). Globulins account for 70 to 90% of the protein and consist of two, four or six subunits of 54,000 daltons. Disulfide reduction of the subunit yields polypeptides of 19,000 to 37,000 daltons. Globulins are rich in arginine, aspartic and glutamic acids, and are deficient in lysine and sulfur-containing amino acids. Nutritional values of the globulin are similar to those of other oilseed globulins; supplementation with the limiting amino acids increases the values. The f i r s t general r e v i e w of the c o m p o s i t i o n and c h a r a c t e r i s t i c s of o i l and p r o t e i n from s e v e r a l s p e c i e s of c u c u r b i t seeds was p u b l i s h e d i n 1972 ( 1 ) . S i n c e t h e n , a resurgence of i n t e r e s t has developed i n the e x p l o T t a t i o n of seeds from w i l d , x e r o p h y t i c c u c u r b i t s , e s p e c i a l l y B u f f a l o gourd ( C u c u r b i t a f o e t i d i s s i m a ) , as u s e f u l , n u t r i t i o u s f o o d s t u f f components ( 2 - 4 ) . ' Reviews c o n c e r n i n g r e s u l t s of f i e l d s t u d i e s o f B u f f a l o gourd p r o d u c t i o n and a d e s c r i p t i o n of the U n i v e r s i t y of A r i z o n a ' s program to domesticate i t have a l s o appeared ( 5 , 6 ) . In a d d i t i o n , seeds of o t h e r c u c u r b i t s seem j u s t as economicFlTy and n u t r i t i o n a l l y promising. In t h i s c h a p t e r , p e r t i n e n t r e s u l t s o f r e s e a r c h on c u c u r b i t seeds w i t h regard to y i e l d , c y t o l o g i c a l s t r u c t u r e , c o m p o s i t i o n , and c h a r a c t e r i z a t i o n s and n u t r i t i o n a l a s p e c t s of o i l and p r o t e i n are summarized.

This chapter not subject to U.S. copyright. Published 1986, American Chemical Society

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Yield

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch020

Seed y i e l d in c u c u r b i t s is seldom i n v e s t i g a t e d because commercial p r o d u c t i o n o f the c a r b o h y d r a t e - r i c h f r u i t is the major c o n c e r n . Wide v a r i a t i o n s in s i z e s and weights o f seeds, numbers o f seeds per f r u i t and even numbers o f f r u i t s per p l a n t seems the r u l e , p a r t i c u l a r l y in w i l d p l a n t s and even w i t h i n one s p e c i e s (7). E s t i m a t i o n s from l i m i t e d o b s e r v a t i o n s o f C. f o e t i d i s s i m a , Z. d i g i t a t a and C. pal ma t a growing w i l d in d e s e r t areas i n d i c a t e t h e o r e t i c a l y i e l d s Trom 500 t o 3,000 l b o f seeds per a c r e Ç. f o e t i d i s s i m a c u l t i v a t e d in n o r t h w e s t e r n Texas y i e l d s a p p r o x i m a t e l y 700 t o 2,000 l b o f seeds per a c r e (10). C. pepo (pumpkin) produces up t o 1,200 l b per acre and an improved s e e d - c o a t l e s s l i n e y i e l d s from 1,200 t o 1,400 l b o f seed per a c r e ( £ , 11). These y i e l d s are comparable to y i e l d s o f o i l s e e d s of commerce. Cytological

Structure

C u c u r b i t seeds are exalbuminous o r l a c k i n g endosperm in the mature state. In such seeds the embryo is l a r g e in r e l a t i o n to the seed a s a w h o l e . I t f i l l s the seed a l m o s t c o m p l e t e l y and i t s body p a r t s , p a r t i c u l a r l y the c o t y l e d o n s , s t o r e the food r e s e r v e s f o r g e r m i n a t i o n . S i n c e the predominant t i s s u e o f the seed is c o t y l e d o n o u s , and s i n c e c o t y l e d o n s are l e a v e s , anatomy and h i s t o l o g y o f t y p i c a l l e a f t i s s u e s u f f i c e t o d e s c r i b e the preponderant p a r t o f the seed. Epidermal c e l l s cover the c o t y l e d o n a r y s u r f a c e f o l l o w e d by p a l i s a d e and abundant parenchyma c e l l s t h a t c o n t a i n the food r e s e r v e s . Vascular t i s s u e s are a l s o present. A c r o s s - s e c t i o n a l view o f a C. d i g i t a t a seed is shown in a scanning e l e c t r o n m i c r o g r a p h (SENfT in F i g u r e 1. The s e c t i o n was t r e a t e d w i t h hexane b e f o r e being s p u t t e r - c o a t e d (12) and is m o r p h o l o g i c a l l y i d e n t i c a l to a s i m i l a r view o f C. pepo (12). The seed c o a t comprises the somewhat t h i n o u t e r boundary o f TRe s e c t i o n and the remainder is composed o f two c o t y l e d o n s separated by the f i r s t " t r u e " l e a v e s o f the embryo. To show the i n t r a c e l l u l a r s t r u c t u r e o f a c u c u r b i t s e e d , t h i s time C. f o e t i d i s s i m a , an SEM a t higher m a g n i f i c a t i o n is given in F i g u r e 2~ W i t h i n the c e l l w a l l a r e l a r g e p a r t i c l e s o f p r o t e i n ( p r o t e i n b o d i e s ) and a c y t o p l a s m i c r e t i c u l u m in which oil-rich spherosomes were embedded. T h i s emptied spherosoma complex, a p p e a r i n g as a net-work, is p r e s e r v e d U 2 , 13) when the sample is prepared by the aqueous method o f A r n o t t ancTWebb U 2 ) . When the method g i v e n f o r F i g u r e 1 was used, the i n t r a c e l l u l a r s t r u c t u r e ( p r o t e i n bodies but no c y t o p l a s m i c r e t i c u l u m ) was s i m i l a r to t h a t o f C. f o e t i d i s s i m a shown by Tu e t a l (13). C y t o l o g i c a l f e a t u r e s o f the c o t y l e d o n s a r e shown in F i g u r e 3, which is a composite e l e c t r o n micrograph p o r t r a y i n g t y p i c a l p a r e n chyma c e l l s t h a t comprise the c o t y l e d o n a r y storage t i s s u e s of £ . f o e t i d i s s i m a , C. pepo, C. p a l ma t a , C. d i g i t a t a , and Apodanthera u n d u l a t a Π Τ ) . The bul7 o f the c y t o p l a s m c o n s i s t s o f two o r g a n e l l e s : spherosomes ( l i p i d b o d i e s ) and p r o t e i n b o d i e s ( a l e u r o n e grains). S t a r c h g r a i n s a r e a b s e n t U ) . Spherosomes a r e about 1 micron in d i a m e t e r , a r e surrounded by h a l f - u n i t membranes (15), and c o n t a i n the r e s e r v e oil o f o i l s e e d s (16). P r o t e i n bodies a r e from 5 t o 20 microns in d i a m e t e r , a r e e n c l o s e d in u n i t membranes, c o n t a i n s t o r a g e p r o t e i n (17, 18), and harbour two i n c l u s i o n s : c r y s t a l l o i d s and globoids. C r y s t a l l o i d s are c r y s t a l l i n e deposits of storage p r o t e i n

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JACKS

Cucurbit Seed Protein and Oil

F i g u r e 1. Scanning e l e c t r o n micrograph of a c r o s s s e c t i o n of a dormant, h e x a n e - t r e a t e d seed of C u c u r b i t a d i g i t a t a . Note o u t e r seed c o a t s , two c o t y l e d o n s ( C ) , and c e n t r a l c l e f t t h a t c o n t a i n s f i r s t " t r u e " l e a v e s between the c o t y l e d o n s . Bar r e p r e s e n t s 1 mm.

F i g u r e 2. Scanning e l e c t r o n micrograph of a mesophyll c e l l of a dormant c o t y l e d o n of B u f f a l o gourd ( C u c u r b i t a f o e t i d i s s i m a ) . T i s s u e was f i x e d in aqueous g l u t a r a l d e h y d e , dehydrated w i t h e t h a n o l and c r i t i c a l l y p o i n t d r i e d . Note c e l l w a l l (W) and i n t r a c e l l u l a r components i n c l u d i n g p r o t e i n bodies (P) and emptied spherosomes t h a t appear as a c y t o p l a s m i c r e t i c u l u m . Bar r e p r e s e n t s 10 ym.

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252

F i g u r e 3. T r a n s m i s s i o n e l e c t r o n micrographs of mesophyll c e l l s of dormant c o t y l e d o n s o f : A, C u c u r b i t a f o e t i d i s s i m a ; B, C u c u r b i t a pepo; C., C u c u r b i t a pa] ma t a ; D, C u c u r b i t a d i g i t a t a ; E, Apodanthera u n d u l a t j T Note c e l l w a l l (W), p r o t e i n body ( P ) , spherosome ( S ) , g l o b o i d ( G ) , and c r y s t a l l o i d ( X ) . In each m i c r o g r a p h , the bar r e p r e s e n t s f i v e m i c r o n s . Reproduced from r e f e r e n c e 14.

20. JACKS

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Cucurbit Seed Protein and Oil

( c u c u r b i t i n ) and are g e n e r a l l y abundant and l a r g e in c u c u r b i t s (17, 18). G l o b o i d s are composed mostly of m e t a l l i c s a l t s of p h y t i c a c i d ΤΓ9, 2 0 ) . Energy d i s p e r s i v e x - r a y a n a l y s i s of C. maxima (squash) g l o b o i d s have shown t h a t , in a d d i t i o n to phosphorus due to p h y t i c a c i d , p o t a s s i u m , magnesium, and sometimes c a l c i u m are l o c a t e d in globoids (17). These c a t i o n s comprise the m e t a l l i c s a l t s of p h y t i n in the g l o b o i d ; they are a b s e n t in the p r o t e i n a c e o u s m a t r i x of the p r o t e i n body in which g l o b o i d s are embedded (17, 1 9 ) . Other i n t r a c e l l u l a r o r g a n e l l e s , such as mitocïïondria, p l a s t i d s , and endoplasmic r e t i c u l a , a l l of which are r a r e l y observed in the c y t o p l a s m of q u i e s c e n t seed c e l l s , are not apparent in q u i e s c e n t c u c u r b i t seed c o t y l e d o n s . N u c l e i , however, are p r e s e n t .

Publication Date: June 18, 1986 | doi: 10.1021/bk-1986-0312.ch020

Composition As w i t h y i e l d s of seeds given above, the amount of seed c o a t per seed v a r i e s c o n s i d e r a b l y , anywhere from 18% (C. pepo) t o 60% ( L a g e n a r i a v u l g a r i s , b o t t l e gourd) (21, 2 2 ) . IndeecT, s e e d - c o a t l e s s l i n e s of C. pepo have l i t t l e or no c o a t (TT, 2 3 ) . The amounts of oil and p r o t e i n in d e c o r t i c a t e d seeds a r e somewhat l e s s v a r i e d . C a l c u l a t i o n s of e a r l i e r data from t h i r t e e n s p e c i e s show t h a t d e c o r t i c a t e d seeds c o n t a i n , by w e i g h t , 49.5 + 2.3% oil and 35.0 +^ 2.4% p r o t e i n a t 95% c o n f i d e n c e i n t e r v a l s in the~2 t e s t (U. More r e c e n t r e p o r t s ( 7 , 24-32) a r e in s u b s t a n t i a l agreement wTth these v a l u e s . Some s t u d i e s r e p o r t oil and p r o t e i n c o n t e n t s o f u n d e c o r t i c a t e d seed (whole seed) or p r o t e i n c o n t e n t of oil-free m e a l . R e c a l c u l a t i o n s to d e c o r t i c a t e d f u l l - f a t seeds f i t these r a n g e s . Oil Unsaturated f a t t y a c i d s are the preponderant f a t t y a c i d s of c u c u r b i t o i l s , and in some seeds conjugated t r i e n e comprises o n e - t h i r d of t h i s u n s a t u r a t i o n . Table I shows the f a t t y a c i d d i s t r i b u t i o n in o i l s of c u c u r b i t seeds ( ] ) . More r e c e n t d e t e r m i n a t i o n s ( 7 , £ 7 , _31» 33) a r e in c l o s e agreement w i t h these r e s u l t s . O c c a s i o n a l l y a s p e c i e s Table I.

Content of F a t t y A c i d s in C u c u r b i t O i l s *

Palmitic Edible Drying

Oils Oils

Stearic

Oleic

Linoleic

Conjugated Trienes

14.2 + 3.18.4 + 2.5 28.5 + 4.147.3 + 4.5 7.8 + 2.9 8.4 + 5.9 22.4 + 5.7 31.0 + 8.4 29.2

+ 6.7

95% c o n f i d e n c e i n t e r v a l s c a l c u l a t e d from the Ζ t e s t . Data from more than one d e t e r m i n a t i o n on a g i v e n s p e c i e s were averaged b e f o r e the means of data from a l l s p e c i e s were c a l c u l a t e d so t h a t each s p e c i e s was e v a l u a t e d , or w e i g h t e d , e q u a l l y . Reproduced from r e f e r e n c e 1.

c o n t a i n s an unusual amount of a given f a t t y a c i d , such as 49% o l e i c a c i d in s e e d - c o a t l e s s C. pepo (26) o r 78% l i n o l e i c a c i d L a g e n a r i a masacarena ( 3 4 ) . C l e a r l y , the "data show t h a t c u c u r b i t seeds are i m p o r t a n t sources of e d i b l e oil, and d i g e s t i b i l i t y s t u d i e s w i t h

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c h i c k s and r a t s s u p p o r t s t h i s ( 2 7 , 33, 3 5 ) , unless conjugated t r i e n e s are p r e s e n t . In t h a t c a s e , the oil is v a l u a b l e as a d r y i n g oil and s t u d i e s of £ . d i g i t a t a and C. palmata seed o i l s i l l u s t r a t e t h e i r u s e f u l n e s s as p r o t e c t i v e c o a t i n g s ( 8 ) . I t is of i n t e r e s t t h a t c a r o t e n o i d pigments ( x a n t h o p h y l l s ) , s t e r o l s ( s p i n a s t e r o l and c h o n d r i l l a s t e r o l ) and a t r i t e r p e n e a l c o h o l have been i d e n t i f i e d in c u c u r b i t seed oil (31 , 36, 3 7 ) . However, c u c u r b i t o i l s such as t h a t from B u f f a l o gourcT are amenable to r e f i n i n g , b l e a c h i n g and d e o d o r i z i n g ( 3 8 ) .

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Protein D e c o r t i c a t e d c u c u r b i t seeds c o n t a i n by w e i g h t about 35% p r o t e i n . T r a d i t i o n a l l y , seed p r o t e i n s are c l a s s i f i e d as g l o b u l i n s and albumins a c c o r d i n g to t h e i r s o l u b i l i t y in c e r t a i n aqueous s o l v e n t s . B i o c h e m i c a l l y , o i l s e e d g l o b u l i n s are g e n e r a l l y c o n s i d e r e d s t o r a g e p r o t e i n s w h i l e albumins are b e l i e v e d to be m e t a b o l i c ( c a t a l y t i c ) proteins. Albumins have not been as thoroughly i n v e s t i g a t e d as have globulins. Albumins i s o l a t e d from C i t r u l l us v u l g a r i s (watermelon) and C. maxima are composed of 9-12 major components t h a t d i f f e r in e l e c t r o p h o r e t i c m i g r a t i o n (39-41 ) and 6-9 components in gel f i l t r a t i o n (40). Many e l e c t r o p h o r e t i c a l l y d i s t i n g u i s h a b l e p r o t e i n s comprise t h e T l b u m i n f r a c t i o n of Cucumis s a t i v u s (cucumber), which is dominated by albumins of m o l e c u l a r w e i g h t of 7000 to 9000 d a l t o n s (42). A thorough study of Cucumis s a t i v u s albumin (43) showed t h a t aïïôut o n e - f o u r t h of i t s p r o t e i n is water s o l u b l e . TRTs low m o l e c u l a r w e i g h t albumin has a s e d i m e n t a t i o n c o n s t a n t o f 2 S (Svedberg u n i t s ) in the a n a l y t i c a l u l t r a c e n t r i f u g e . I t was concluded t h a t , b e s i d e s c u c u r b i t g l o b u l i n s , a l a r g e p o r t i o n of the albumins a l s o a c t s b i o c h e m i c a l l y as storage p r o t e i n , b u t f o r s u l f u r in a d d i t i o n to n i t r o g e n s i n c e t h e i r amino a c i d c o m p o s i t i o n is s i m i l a r to t h a t o f n i t r o g e n - r i c h g l o b u l i n , y e t they c o n t a i n an e x c e p t i o n a l l y high c o n t e n t of c y s t e i n e (8.9% of the t o t a l amino a c i d s ) . C u c u r b i t seed g l o b u l i n s , which a c c o u n t f o r about 70 to 90% o f the t o t a l p r o t e i n c o n t e n t , c o n t a i n about 18% n i t r o g e n , are s o l u b l e in 10% s a l t s o l u t i o n s from which they r e a d i l y c r y s t a l l i z e upon d i l u t i o n , and are a l s o s o l u b l e in both a c i d i c and b a s i c s o l u t i o n s of low i o n i c s t r e n g t h . S i n c e the c l a s s i c a l i s o l a t i o n of c r y s t a l l i n e c u c u r b i t i n in 1892 ( 4 4 ) , many chemical and p h y s i c o c h e m i c a l s t u d i e s of c u c u r b i t i n have been c o n d u c t e d . V a r i e d r e s u l t s from d e t e r m i n a t i o n s of the m o l e c u l a r weight of the n a t i v e o l i g o m e r i c g l o b u l i n s and the number and m o l e c u l a r weights of i t s s u b u n i t s have been o b t a i n e d . In a d d i t i o n to s l i g h t n a t u r a l v a r i a t i o n s among s p e c i e s , the v a r i a b i l i t y appears due to p r e p a r a t i v e procedures as w e l l as to c o n d i t i o n s and modes of a n a l y s e s . E a r l i e r s t u d i e s of the m o l e c u l a r weight of the o l i g o m e r i c g l o b u l i n , the number of s u b u n i t s and t h e i r e l e c t r o p h o r e t i c h e t e r o g e n e i t y have been reviewed U ) . R e s u l t s p r i o r to 1972 i n d i c a t e d t h a t c u c u r b i t i n is a hexamer of about 340,000 m o l e c u l a r w e i g h t and s e d i m e n t a t i o n c o n s t a n t s in three s t a t e s of a s s o c i a t i o n d i s a s s o c i a t i o n are 3 S (monomeric s u b u n i t ) , 7 S and 12 S. At a c i d i c pH v a l u e s or high i o n i c s t r e n g t h s , c u c u r b i t i n appears homogeneous d u r i n g e l e c t r o p h o r e s i s or u l t r a c e n t r i f u g a t i o n ; however, a t n e u t r a l pH v a l u e s and low i o n i c s t r e n g t h s , the p r o t e i n c o n t a i n s up to four major components.

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255

A l a t e r study (45) i n d i c a t e s t h a t c u c u r b i t i n from pumpkin has a m o l e c u l a r weight o f TT2,000 d a l t o n s t h a t can be e l e c t r o p h o r e t i c a l l y s e p a r a t e d i n t o s u b u n i t s of 63,000 and 56,000 d a l t o n s . Reduction of d i s u l f i d e s produces p o l y p e p t i d e s o f 36,000 and 22,000 d a l t o n s . G l o b u l i n s from s i x c u c u r b i t s examined c h r o m a t o g r a p h i c a l l y (46) have m o l e c u l a r weights o f 220,000 to 260,000 d a l t o n s t h a t e x h i b i t p r e d o m i n a n t l y 10.4 - 11.2 S v a l u e s (about 95% o f the t h r e e g l o b u l i n fractions). C u c u r b i t i n from Cucumis s a t i v u s appears a tetramer o f 240,000 d a l t o n s composed of f o u r s u b u n i t s of 54,000 d a l t o n s ( 4 2 ) . D i s u l f i d e r e d u c t i o n produces s i x p o l y p e p t i d e s u b u n i t s r a n g i n g T r o m 37,000 t o 19,000 d a l t o n s . A more r e c e n t study of c u c u r b i t i n i s o l a t e d from s e v e r a l s p e c i e s (47) i n d i c a t e s t h a t i t is composed of o n l y 12 S (90% o f the g l o b u l i n ) and 18 S v a l u e s . By e l e c t r o p h o r e t i c a n a l y s i s and chromatography combined w i t h u l t r a c e n t r i f u g a t i o n , n a t i v e c u c u r b i t i n appears a hexamer of about 325,000 d a l t o n s (12 S f o r m ) , composed of s i x monomeric s u b u n i t s of about 54,000 d a l t o n s e a c h , and forms a dimer of 630,000 d a l t o n s (18 S f o r m ) . The l a r g e and small p o l y p e p t i d e s u b u n i t s of the monomer, prepared by r e d u c t i o n w i t h 2 - m e r c a p t o e t h a n o l , range from 33,000 to 36,000 d a l t o n s and 22,000 to 25,000 d a l t o n s , r e s p e c t i v e l y . S t u d i e s o f the secondary s t r u c t u r e of c u c u r b i t i n have shown i t s c o n f o r m a t i o n a l modes c o n s i s t o f 5% a - h e l i c a l , 32% p l e a t e d s h e e t , and 62% unordered s t r u c t u r e s ( 4 8 ) . These v a l u e s are s i m i l a r in d i s t r i b u t i o n to those o f otiïer o i l s e e d g l o b u l i n s ( 4 8 ) . The amino a c i d c o m p o s i t i o n s of t o t a l c u c u r b i t seed p r o t e i n (meal) and p u r i f i e d g l o b u l i n a r e presented in Table I I . More r e c e n t c o m p o s i t i o n a l data ( 7 , 29, 32, 4 3 , 4 5 , 46, 49-51) s i n c e those summarized e a r l i e r (T) a r e TrT s u b s t a n t i a l agreement w i t h the mean d i s t r i b u t i o n shown in T a b l e I I , which i n d i c a t e s t h a t c u c u r b i t seeds, as o i l s e e d s in g e n e r a l , are r i c h in g l u t a m i c a c i d (and g l u t a m i n e ) , a r g i n i n e , and a s p a r t i c a c i d (and a s p a r a g i n e ) . The abundance of these n i t r o g e n - r i c h amino a c i d s accounts f o r the 18% n i t r o g e n c o n t e n t of c u c u r b i t p r o t e i n . Other n o n p r o t e i n amino a c i d s have been i d e n t i f i e d in c u c u r b i t seeds ( 5 2 ) , i n c l u d i n g 3 - a m i n o - 3 - c a r b o x y p y r o l i d i n e ( c u c u r b i t i n e ) , whicTPhas a n t h e l m i n t i c a c t i v i t y ( 5 3 ) . From amino a c i d c o m p o s i t i o n s , e v a l u a t i o n s oT~~the n u t r i t i o n a l p o t e n t i a l s of c u c u r b i t meals and g l o b u l i n s can be c a l c u l a t e d a c c o r d i n g to FA0/WH0 ( 5 4 ) . The A:E r a t i o s , which a r e the amounts o f each e s s e n t i a l amino a c i d r e l a t i v e to the t o t a l amount of e s s e n t i a l amino a c i d s , a r e shown in T a b l e I I . These data i n d i c a t e t h a t , l i k e most o t h e r o i l s e e d s , c u c u r b i t seeds a r e d e f i c i e n t in l y s i n e and s u l f u r - c o n t a i n i n g amino a c i d s . However, s u l f u r - c o n t a i n i n g amino a c i d s a r e c o n s i d e r a b l y high in C i t r u l l u s c o l o c y n t h i s ( e g u s i , a n c e s t r a l watermelon) seed p r o t e i n and exceed the suggested l e v e l in FA0/WH0 r e f e r e n c e p r o t e i n ( 5 5 ) . A p r o t e i n t h a t is unduTy r i c h in the ten e s s e n t i a l amino a c i d s would n o t p r o v i d e s u f f i c i e n t n i t r o g e n f o r o t h e r m e t a b o l i c processes w i t h o u t o b l i g a t o r y c a t a b o l i s m of the e s s e n t i a l amino a c i d s . Thus, the p r o p o r t i o n of the t o t a l n i t r o g e n i n t a k e t h a t e s s e n t i a l amino a c i d s form i n d i c a t e how a given p r o t e i n f u l f i l l s n u t r i t i o n a l requirements f o r p r o t e i n s . T h i s p r o p o r t i o n , the E/T r a t i o ( 5 4 ) , i n d i c a t i v e of the amount of p r o t e i n n i t r o g e n s u p p l i e d by e s s e n t i a l amino a c i d s , is ( i n g of e s s e n t i a l amino a c i d s per g of n i t r o g e n ) 2.18 f o r c u c u r b i t meal and 2.67 f o r c u c u r b i t g l o b u l i n . The value f o r meal is s i m i l a r in magnitude to those f o r o t h e r seeds and the v a l u e

1.0

+ O.3

τ τ τ τ

+ 1.3 1.9 2.4 1.3 O.5

+ O.5 Τ O.7 Τ 1.4 τ O.4 τ O.4 τ O.4 τ O.1 τ O.1 τ 1.3 124 187 124 52 126 78 46 86 149

A/E R a t i o 25

O.2 2.5 τ O.2 5.1 τ O.2 5.9 τ O.7

1.7

1.1

O.6

+ O.3 Τ O.1 Τ O.3 Τ O.2 τ O.2 τ O.5 τ O.3 τ O.2 τ O.3 τ O.3 τ O.3

16.6 τ 9.8 τ 20.0 τ 5.1 τ

3.8 5.9 5.2

2.1

1.5 4.8 8.3 3.0 3.0 7.3 3.2 112 194 70 66 171 75 49 89 138

Globulins

4.2 4.8 4.2 2.2