Fruit and Cereal Bioactives

Fruit and Cereal BioactivesSources, Chemistry, and Applications

Fruit and Cereal BioactivesSources, Chemistry, and Applications

Edited by

lu zlem Tokus og Clifford Hall III

Boca Raton London New York

CRC Press is an imprint of the Taylor & Francis Group, an informa business

CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 2011 by Taylor and Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10 9 8 7 6 5 4 3 2 1 International Standard Book Number: 978-1-4398-0665-4 (Hardback) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data Fruit and cereal bioactives : sources, chemistry, and applications / edited by Ozlem Tokusoglu, Clifford Hall III. p. ; cm. Includes bibliographical references and index. Summary: Presenting up-to-date data in an easy-to-use format, this comprehensive overview of the chemistry of bioactive components of fruits and cereals addresses the role of these compounds in determining taste, flavor, and color, as well as recent claims of anticarginogenic, antimutagenic, and antioxidant capabilities. It provides detailed information on both beneficial bioactives such as phenolics, flavonoids, tocols, carotenoids, phytosterols, and avenanthramides and toxicant compounds including mycotoxins; aflatoxins, ocratoxin A, patulin, citrinin, cyclopiazonic acid, fumonisin, and zearalenon. A valuable resource for current knowledge and further research, it offers critical reviews, recent research, case studies, and references--Provided by publisher. ISBN 978-1-4398-0665-4 (hardcover : alkaline paper) 1. Fruit--Composition. 2. Grain--Composition. 3. Phytochemicals--Physiological effect. I. Tokusoglu, Ozlem, editor. II. Hall, Clifford, III, editor. [DNLM: 1. Fruit--chemistry. 2. Cereals--chemistry. 3. Dietary Supplements. 4. Phytotherapy. 5. Plant Extracts--therapeutic use. WB 430] QK865.F78 2011 664.8--dc22 Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com 2010044816

To my mother, retired teacher zden Tokuolu & my father, retired senior colonel Armaan Tokuolu, for their great emotional support and cordial encouragements.

zlem Tokus og lu

ContentsPreface....................................................................................................................................................... ix Editors........................................................................................................................................................ xi Contributors.............................................................................................................................................xiii

Part I Introduction 1. Introducton to Bioactives in Fruits and Cereals. ......................................................................... 3 zlem Tokuolu and Clifford Hall III 2. Health Promoting Effects of Cereal and Cereal Products. .......................................................... 9 Joseph M. Awika

Part I I Chemistry and Mechanisms of Beneficial BioactivesinFruits and Cereals 3. Phytochemicals in Cereals,Pseudocereals, and Pulses. ............................................................. 21 Clifford Hall III and Bin Zhao 4. Phenolic and Beneficial Bioactives in Drupe Fruits.................................................................... 83 zlem Tokuolu 5. Bioactive Phytochemicals in Pome Fruits. ................................................................................. 107 zlem Tokuolu 6. Phytochemicals in Citrus and Tropical Fruit............................................................................ 123 Mehmet alar Tlbek 7. Phytochemical Bioactives in Berries............................................................................................143 zlem Tokuolu and Gary Stoner 8. Phenolic Bioactives in Grapes and Grape-Based Products.......................................................171 Violeta Ivanova and Marina Stefova 9. Nut Bioactives: Phytochemicals and Lipid-Based Components ofAlmonds,Hazelnuts,Peanuts, Pistachios, and Walnuts. ......................................................185 Biagio Fallico, Gabriele Ballistreri, Elena Arena, and zlem Tokuolu 10. Nut Bioactives: Phytochemicals and Lipid-Based Components ofBrazilNuts,Cashews,Macadamias, Pecans, and Pine Nuts................................................213 Biagio Fallico, Gabriele Ballistreri, Elena Arena, and zlem Tokuolu 11. Bioactive Lipids in Cereals and Cereal Products...................................................................... 229 Ali A. Moazzami, Anna-Maija Lampi, and Afaf Kamal-Eldinvii

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Contents

Part II I Mycotoxic Bioactives of Fruits and Cereals12. Mycotoxic Bioactives in Cereals and Cereal-Based Foods. ...................................................... 253 Anuradha Vegi 13. Control Assessments and Possible Inactivation Mechanisms onMycotoxinBioactivesofFruits and Cereals. ........................................................................ 273 Faruk T. Bozolu and zlem Tokuolu 14. Control of Mycotoxin Bioactives in Nuts: Farm to Fork............................................................291 Mohammad Moradi Ghahderijani and Hossein Hokmabadi

Part I V Functionality, Processing, Characterization, and Applications of Fruit and Cereal Bioactives15. Isolation Characterization of Bioactive Compounds in Fruits and Cereals............................319 Xiaoke Hu and Zhimin Xu 16. Effect of Bioactive Components on Dough Rheology, Baking, and Extrusion....................... 337 Joseph M. Awika 17. Impacts of Food and Microbial Processing on the Bioactive PhenolicsofOliveFruitProducts. .............................................................................................. 347 Moktar Hamdi 18. Antioxidant Activity/Capacity Assay Methods Applied to Fruit and Cereals.........................361 Reat Apak, Esma Ttem, Mustafa zyrek, and Kubilay Gl 19. Supercritical Fluid Extraction of Bioactive Compounds from Cereals. ................................. 385 Jose L. Martinez and Deepak Tapriyal 20. Analytical Methodology for Characterization of Grape and Wine Phenolic Bioactives....... 409 Marina Stefova and Violeta Ivanova 21. High Pressure Processing Technology on Bioactives in Fruits and Cereals. ......................... 429 zlem Tokuolu and Christopher Doona Index. ..................................................................................................................................................... 443

PrefaceInterest in bioactive compounds of fruit and cereals has reached a new high in recent years. The scientific and commercial attention devoted to fruit and cereal bioactives has been accentuated even further by efficiency reports regarding the beneficial and toxic health effects of such compounds. The beneficial bioactives of many fruit and cereals have been declared to possess anticarcinogenic, antimutagenic effects in test animals. Recently, the strong antioxidant capacities of many edible fruits and cereals have been revealed. These many bioactive compounds are responsible for several important characteristics of fruit and cereals: taste, flavor, color alteration, and antioxidant activity. Natural toxicant bioactives as mycotoxins have also been detected in specific fruits and cereals. The specific focus for Fruit and Cereal Bioactives is on the chemistry of beneficial and nutritional bioactives (phytochemicals such as phenolics, flavonoids, tocols, carotenoids, phytosterols, avenanthramides, alkylresorcinols, some essential fatty acids) and toxicant bioactives (mycotoxins, aflatoxins, ocratoxin A, etc.) from sources such as pome, stone, and berry fruits, citrus fruits, tropical fruits and nuts, various cereals (and pseudocereals), pulses (e.g., legumes and edible beans), and so on. Overall, this book is a comprehensive and detailed reference guide to both major natural beneficial phytochemical bioactives and mycotoxic bioactives in edible fruits and cereals covering all the latest research from a wide range of experts. This book is intended for senior undergraduate and graduate students, academicians, and those in government and the fruit and cereal industry. It provides a practical reference for a wide range of experts: fruit and cereal scientists, chemists, biochemists, nutritionists, fruit and cereal processors, government officials, commercial organizations, and other people who need to be aware of the main issues concerning bioactives. Each chapter reviews dietary sources, occurrences, chemical properties, desirable and undesirable health effects, antioxidant activity, evidentiary findings, as well as toxicity of the above-mentioned bioactives and has been individually highlighted based on the fruit and cereal type. Fruit and Cereal Bioactives presents unique, up-to-date, and unified data of fruit and cereal chemistry from a biochemical standpoint.

zlem Tokus og lu

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Editorszlem Tokus og lu, who was born in zmir, Turkey, completed her bachelor (1992) and master (1996) degrees at EGE University from the Department of Chemistry and completed her doctorate at EGEUniversityfrom the Department of Food Engineering (2001). She worked as a research assistant and Dr. Assistant at EGE University from 1993 to 2001. She was the research assistant at the Food Science and Nutrition Department at the University of FloridaGainesville during 19992000. Dr. Tokuolu has been an assistant professor at Celal Bayar University, Manisa, Turkey and is currently working there in the Department of Food Engineering. She is focusing on food quality control, food chemistry, food safety, and food processing technologies on traditional foods and beverages. Her specific study areas are phenolics, phytochemicals, bioactive antioxidative components, bioactive lipids, and their determinations by instrumental techniques, their effects on food and beverages quality, and the novel food processing effects on their levels. Dr. Tokuolu performed academic research studies and presentations at Geneva, Switzerland in 1997; Gainesville, Florida in 1999; AnaheimLos Angeles, California in 2002; Sarawak, Malaysia in 2002; Chicago, Illinois in 2003; Katowice-Szczyrk, Poland in 2005; Ghent, Belgium in 2005; Madrid, Spain in 2006; New Orleans, Louisiana in 2008; Athens, Greece in 2008; AnaheimLos Angeles, California in 2009; and Skopje, the Republic of Macedonia in 2009; Chicago, Illinois in 2010; Munich, Germany in 2010. She was also a visiting professor at the School of Food Science, Washington State University, Pullman, in the state of Washington for one month during 2010. Dr. Tokuolu has professional affiliations at the Institute of Food Technologists (IFT) and the American Oil Chemists Society (AOCS) in the United States and has a professional responsibility with the Turkey National Olive and Olive Oil Council (UZZK) as a research and consultative board member and as a Turkish Lipid Group (YABITED) founder administrative board member and consultative board member in the European Federation for Science and Technology (Euro Fed Lipid). Dr. Tokuolu has 78 international studies containing 25 papers published in peer-reviewed international journals covered by the Science Citation Index (SIC) and 11 papers published in peer-reviewed international index covered journals, 42 presentations (as orals and posters) presented at the international congress and other organizations. She has advised two masters students to completion. Dr. Tokuolu has several editorial assignments in international index covered journals.Clifford Hall III completed his bachelor degree in 1988 at the University of WisconsinRiver Falls; his masters (1991) and doctoral (1996) degrees at the University of NebraskaLincoln in the area of food science and technology. He completed a postdoctoral experience at the University of Arkansas in Fayetteville. Dr. Hall is currently an associate professor in the Department of Cereal and Food Sciences in the School of Food Systems at North Dakota State University (NDSU). He is the associate director of the Great Plains Institute of Food Safety and food science coordinator for the Food Science program at NDSU. Much of his research deals with lipid oxidation and antioxidant chemistry, stability of phytochemicals in food processing, and utilization of nontraditional ingredients in food systems. The stability of flaxseed bioactives and antioxidant activity of raisins has been his major focus recently, including the evaluation of flaxseed lignan stability in extruded bean snacks. He has published his research in 28 peer-reviewed international journals, and 12 proceedings, and has published 10 book chapters. His research has created 60 oral and poster presentations at the American Oil Chemists Society, Institute of Food Technologists, International Society of Nutraceutical and Functional Foods, and AACC International annual meetings. He has advised five PhD and two masters students to completion and currently advises two PhD and three masters students. He has also mentored 28 undergraduate researchers and has served on 26 graduate student committees. Professionally, Clifford has been most active in the AOCS and AACC International.xi

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Editors

He served as the secretary/treasurer, 2003; vice chairperson, 2004; and chairperson, 20052007 for the Lipid Oxidation and Quality Division of the American Oil Chemists Society. He served as the chair of the Best Paper Competition Committee for the Lipid Oxidation and Quality Division, 20032006. He has also served as the chairperson of the Education Division for AACC International, 20072009 and on the AACC International Foundation as a board member, 2008 to the present; and chair, 2009. He has also served as an associate editor from 1998 to 2006 and senior associate editor from 2006 to the present for the Journal of the American Oil Chemists Society. In addition, he is an ad hoc reviewer for Food Chemistry, Journal of Food Science, and Journal of Agricultural and Food Chemistry.

ContributorsReat Apak Department of Chemistry Istanbul University stanbul, Turkey Elena Arena Dipartimento di OrtoFloroArboricoltura e Tecnologie Agroalimentari (DOFATA) Sez. Tecnologie AgroAlimentari Universit degli Studi di Catania Catania, Italy Joseph M. Awika Soil and Crop Science Department Texas A&M University College Station, Texas Gabriele Ballistreri Dipartimento di OrtoFloroArboricoltura e Tecnologie Agroalimentari (DOFATA) Sez. Tecnologie AgroAlimentari Universit degli Studi di Catania Catania, Italy Faruk T. Bozolu Department of Food Engineering Engineering Faculty Middle East Technical University Ankara, Turkey Christopher Doona U.S. Army Natick Soldier Research Development and Engineering Center DoD Combat Feeding Directorate Natick, Massachusetts Biagio Fallico Dipartimento di OrtoFloroArboricoltura e Tecnologie Agroalimentari (DOFATA) Sez. Tecnologie AgroAlimentari Universit degli Studi di Catania Catania, Italy Mohammad Moradi Ghahderijani Department of Plant Protection Pistachio Research Institute of Iran Rafsanjan, Iran Kubilay Gl Department of Chemistry Istanbul University stanbul, Turkey Clifford Hall III School of Food Systems North Dakota State University Fargo, North Dakota Moktar Hamdi National Institute of Applied Sciences andTechnology University of 7th November at Carthage Laboratory of Microbial Ecology and Technology Tunis, Tunisia Hossein Hokmabadi Department of Horticulture Pistachio Research Institute of Iran Rafsanjan, Iran Xiaoke Hu Department of Chemistry Louisiana State University Baton Rouge, Louisiana Violeta Ivanova Institute of Chemistry Faculty of Natural Sciences and Mathematics Ss Cyril and Methodius University Skopje, Republic of Macedonia Afaf Kamal-Eldin Department of Food Science Swedish University of Agricultural Sciences Uppsala, Sweden Anna-Maija Lampi Department of Chemistry and Applied Microbiology University of Helsinki Helsinki, Finlandxiii

xiv Jose L. Martinez Thar Process, Inc. Pittsburgh, Pennsylvania Ali A. Moazzami Department of Food Science Swedish University of Agricultural Sciences Uppsala, Sweden Mustafa zyrek Department of Chemistry Istanbul University stanbul, Turkey Marina Stefova Institute of Chemistry Faculty of Natural Sciences and Mathematics Ss Cyril and Methodius University Skopje, Republic of Macedonia Gary Stoner Department of Internal Medicine The Ohio State University Columbus, Ohio Deepak Tapriyal Thar Process, Inc. Pittsburgh, Pennsylvania zlem Tokuolu Department of Food Engineering Celal Bayar University Manisa, Turkey Mehmet alar Tlbek Northern Crops Institute North Dakota State University Fargo, North Dakota Esma Ttem Department of Chemistry Istanbul University stanbul, Turkey Anuradha Vegi Department of Veterinary and MicrobiologicalSciences North Dakota State University Fargo, North Dakota

Contributors

Zhimin Xu Department of Food Science Louisiana State University Agriculture Center Baton Rouge, Louisiana Bin Zhao Kraft Foods, Inc. East Hanover, New Jersey

Part I

Introduction

1Introduction to Bioactives in Fruits and Cerealszlem Tokus og lu and Clifford Hall III ContentsPhytochemicals in Fruit and Cereals. .......................................................................................................... 3 Phenolics in Fruit and Cereals............................................................................................................... 3 Carotenoids in Fruit and Cereals........................................................................................................... 5 Functional Lipids and Lipid Soluble Constituents................................................................................ 5 Mycotoxic Bioactives in Fruits and Cereals............................................................................................... 7 Concluding Remarks. .................................................................................................................................. 7 References................................................................................................................................................... 7 Fruit and cereal bioactives are classified as phytochemicals and toxicant secondary metabolites. Phytochemicals containing polyphenols, carotenoids, and functional lipids are naturally derived substances that have health-promoting, and/or nutraceutical and medicinal proper while mycotoxigenic bioactives are toxic substances that are secondary metabolites synthesized by toxigenic fungal species. A wide variety of mycotoxins are produced by various fungi, often a single fungal species can synthesize more than one type of mycotoxic bioactive under optimal conditions. Interest in the bioactive compounds of fruit and cereals has reached a new high in recent years. Especially, the scientific and commercial attention in fruit and cereal bioactives have been accentuated by efficiency reports regarding both beneficial and toxical health effects of such compounds. According to the National Institutes of Health (NIH), bioactive food phytochemicals including polyphenols, carotenoids, and functional lipids are constituents in foods or dietary supplements, other than those needed to meet basic human nutritional needs, that are responsible for changes in health status. Major sources of these bioactive food components are plants, especially fruits, vegetables, and cereals. But major sources of both phytochemicals and mycotoxins are fruits, nuts, and more major in cereals. In this book context, a brief description of the chemistry, sources, and applications of the abovementioned major bioactives in fruits and cereals.

Phytochemicals in Fruit and CerealsPhenolics in Fruit and CerealsAs the name suggests, phytochemicals working together with chemical nutrients found in fruits, cereals, and nuts may help slow the aging process and reduce the risk of many diseases, including cancer, heart disease, stroke, high blood pressure, cataracts, osteoporosis, and urinary tract infections (Meskin et al. 2003; Omaye et al. 2000). Polyphenols occur as plant secondary metabolites. Their ubiquitous presence in plants and plant foods, favors animal consumption and accumulation in tissues. Polyphenols are widely distributed in the plant kingdom and represent an abundant antioxidant component of the human diet (Ho, Rafi and Ghai, 2007). Interest in the possible health benefits of polyphenols has increased due to the3

4

Fruit and Cereal Bioactives: Sources, Chemistry, and Applications

corresponding antioxidant capacities (Gharras, 2009). Recent evidences show that there is a great interest to anticarcinogenic effects of polyphenolic compounds, as well as the potential to prevent cardiovascular and cerebrovascular diseases (Cheynier 2005). Polyphenols divide into several subgroups including flavonoids, hydroxybenzoic and hydroxycinnamic acids, lignans, stilbens, tannins, and coumarins that have specific physiological and biogical effects (Andersen and Markham 2006; Meskin et al. 2003; Tokuolu 2001; Figure 1.1). Flavonoids are a chemically defined family of polyphenols that includes several thousand compounds. The flavonoids have a basic structure (Figure 1.2), and several subclasses of flavonoids are characterized by a substitution pattern in the B- and C-rings. The main subclasses of flavonoids include flavan-3-ols, flavonols, flavones, flavanones, isoflavones, anthocyanidins, anthocyanins, flavononols, and chalcons (Figure 1.3) that are distributed in plants and food of plant origin (Crozier, Jaganath, and Clifford 2006). Flavonoids in the circulation may protect against cardiovascular disease through their interaction with low-density lipoprotein (LDL). Biochemical and clinical studies in both humans and experimental animals have suggested that oxidized low-density lipoprotein (oLDL) has its atherogenic action through the formation of lipid hydroperoxides and the products derived therefrom. The in vivo antioxidant status of the LDL particles and the plasma are thus important determinants of the susceptibility of LDL to lipid peroxidation (Hertog et al. 1993). Many of the phytochemicals and some vitamins (vitamin E, tocopherol) have antioxidant activity in vitro, which has led to the use of the general term antioxidants.Phenolic compounds

Flavonoids Flavons Phenolic acids Isoflavons Hydroxybenzoic acids Flavonols Hydroxycinnamiz acids Flavanols Flavanones Anthocyanidins Anthocyanins Flavononols Chalcons Lignans Sesamol Sesamin Sesamolin Sesamolinol Stilbens Resveratrol Piceatannol Piceid Pinosylvin Rhapontisin Tamoxiphen Derivative Phytoalexins Tannins

Coumarins

Hydrolyzed Condensed

Figure 1.1 Family of phenolic compounds. (From Andersen, Q. M., and Markham, K. R., Flavonoids. Chemistry, Biochemistry, and Applications, CRC Press, Taylor & Francis, Boca Raton, FL, 2006; Meskin, M. S., Bidlack W. R., Davies, A. J., Lewis, D. S., and R. K. Randolph, Phytochemicals: Mechanisms of Action. CRC Press, Boca Raton, FL, 2003; Tokuolu, ., The Determination of the Major Phenolic Compounds (Flavanols, Flavonols, Tannins and Aroma Properties of Black Teas, PhD Thesis, Department of Food Engineering, Bornova, Izmir, Turkey: Ege University, 2001).)

3 2 8 7 A 6 5 Figure 1.2 Chemical structure of flavonoids. 4 B O C 3 6 5 4

Introduction to Bioactives in Fruits and CerealsFlavonoids

5

Chalcons Flavons Apigenin Luteloin Baikalein Krysin Diosmin Genkvain Izorhoifolin Rhoifolin Tektokirisin Flavonols Quercetin Kaempferol Miricetin Quercitrin Isoquercitrin Rhamnetin Isorhamnetin kaempferid Rutin Astragalin Hiperosid Flavononols (Dihydroflavonols) Anthocyanidins Cyanidin Malvinidin Delfinidin Pelargonidin Petunidin Peonidin

Isoflavons Daidzein Genistein Biokenin A Formononetin Glisitein Daidzin Genistin Glisitin 6 -O-Asetildaidzin 6 -O-Asetilgenistin 6 -O-Asetilglisitin 6 -OMalonildaidzin 6 -OMalonilgenistin 6 -OMalonilglisitin

Flavan-3-ols (+)Catechin ()Epicatechin ()Epicatechingallate ()Epigallocatechin ()Epigallocatechingallate

Flavanons Hesperetin Hesperitin Naringenin Naringin Narirutin Didimin Eriositrin Eriodiktiol Neoriositrin Neohesperitin Izosakuranetin Pinosembrin Ponsirin Prunin

Anthocyanins Grape extract

Figure 1.3 Flavonoid family in food plants. (Adopted from Tokuolu, ., The Determination of the Major Phenolic Compounds (Flavanols, Flavonols, Tannins and Aroma Properties of Black Teas, PhD Thesis, Department of Food Engineering, Bornova, Izmir, Turkey: Ege University, 2001; Merken, H. M., and Beecher, G. R., J. Agric. Food Chem., 48(3), 57995, 2000; Beecher, G. R., Antioxidant Food Supplements in Human Health, Academic Press, New York, 1999; Fennema, O. R., Food Chemistry, Marcel Dekker, New York, 68196, 1996; Vinson, J. A., Dabbagh, Y. A., Serry, M. M., and Jang, J., J. Agric. Food Chem., 43, 28002802, 1995.)

Carotenoids in Fruit and CerealsCarotenoids (Figure 1.4), a group of lipid-soluble compounds responsible for yellow, orange, red, and violet colors of various fruits and cereals products, are one of the most important groups of natural pigments, owing to their wide distribution, structural diversity, and numerous biological functions (Astorg 1997; Fraser and Bramley 2004). The provitamin A activity of some carotenoid bioactives, recently, have demonstrated to be effective in preventing chronic diseases such as cardiovascular disease and skin cancer. Carotenoid bioactives are classified into four groups: carotenoid hydrocarbons, carotenoid alcohols (xanthophylls), carotenoid ketons, carotenoid acids. Hydrocarbon carotenoids are known as carotenes, and the oxygenated derivatives are termed xanthophylls (Astorg 1997; Fraser and Bramley 2004; Lee and Schwartz 2005)

Functional Lipids and Lipid Soluble ConstituentsThere has been a great interest concerning functional lipids in cereals due to their promotion for health and preventing diseases. Fatty acids play a central role in growth and development through their roles in membrane lipids, as ligands for receptors and transcription factors that regulate gene expression, as a precursor for eicosanoids, in cellular communication, and through direct interactions with proteins. The main fatty acids in cereals are the saturated fatty acids, palmitic (16:0) and stearic (18:0), the monounsaturated fatty acid oleic acid (18:1), and the diunsaturated fatty acid inoleic acid (18:2) existing with smaller amounts of other fatty acids. These fatty acids are mainly assembled in glycerolipids; that is, triacylglycerols (TAG) and variable amounts of phospholipids (PL), glycolipids (GL), in sterol esters (SE), and waxes (or policosanols) in the different cereal grains. Lipid soluble vitamins tocopherols and amphiphilic lipids alkylresorcinols, and terpen alcohol compounds are also important bioactive constituents in cereal grains (Figure 1.5). Cereal lipids have high levels of tocotrienols that coexist with tocopherols, which are the biologically most active antioxidants

6


Lycopene 15 BCO 15 all-trans--carotene BCO-2 10 9

-carotene OH

HO

Lutein

HO CH3

-cryptoxanthin CH3 H 3C OH

H 3C

CH3

HO

CH3 Zeaxanthine

CH3

CH3

H3C CH3

Figure 1.4 Major carotenoids. (Ross, C. A. and Harrison, E. H., Handbook of Vitamins, Taylor & Francis Group, Boca Raton, FL, 139, 2007.)

R1 HO R2 R1 HO R2 OTocotrienolsOH

HOTocopherols

H HO

H

H

HO

H

Trematol

H

Fernenol

H HO

H HO

H

H

H

Isoarborinol

H

Sorghumol R1 R2

HOAlkyresorcinols

n=13-23

H

H

H

H

H

H

HO

HO Simiarenol Triterpen alcohols -Amyrin R1= methyl, R2 = hydrogen -Amyrin R1= hydrogen, R2 = methyl

Figure 1.5 Some lipid soluble constituents and cereal grains.

Introduction to Bioactives in Fruits and Cereals

7

(Peterson 2004). Alkylresorcinols have been shown to have bioactivities in vitro and in vivo experiments. They increase the -tocopherol level in rat liver and lung by possibly inhibiting -tocopherol metabolism (Ross, Kamal-Eldin, and Aman 2004). Sterols and sterol-based constituents, terpenoids play a role in traditional herbal remedies and it is reported they show antibacterial, cholesterol-lowering, antiatherogenic, and anticarcinogenic effects. Phytosterols appear not only to play an important role in the regulation of cardiovascular disease but also to exhibit anticancer properties (Jones & AbuMweis, 2009). Those beneficial bioactives of many fruits and cereals have been declared to possess anticarcinogenic and antimutagenic effects in test animals. Recently, it has also been detected in the strong antioxidant capacities of many edible fruits and cereals.

Mycotoxic Bioactives in Fruits and CerealsMycotoxigenic bioactives are toxic substances that are produced by the secondary metabolism of various fungal species (Ho, Rafi and Ghai, 2007). Various studies have been reported about their high toxicity and the possible risk for consumer health. Fungal spoilage of cereals and mycotoxic bioactive production is most important. It has been shown that the presence of fungi on fruits is not necessarily associated with mycotoxin (aflatoxins, ochratoxin A, patulin, citrinin, T2, etc.) contamination. The mycotoxin formation depends more on endogenous and environmental factors than fungal growth does (Andersen and Thrane 2006). The studies indicated that Alternaria, and Fusarium in fruit and cereals may pose a mycotoxin risk. During spoilage of cherries and apples, Penicillum expansum is known to produce patulin. Both Alternaria and Fusarium are able to produce additional mycotoxic bioactives in moldy fruit samples: alternariols and aurofusarin. Penicillum verrucosum is known to produce Ochratoxin A in many cereals. Fusarium is able to produce zearalenone in addition to Ochratoxin A from P.verrucosum in moldy cereals. Aspergillus ochraceus, A.niger, and A.carbonarious produce Ochratoxin A in dried fruits such as raisins and currants (Iamanaka et al. 2006).

Concluding RemarksFruit and Cereal Bioactives are comprised of the specific focus on the chemistry of beneficial and nutritional bioactives (phytochemicals such as phenolics, flavonoids, tocols, carotenoids, phytosterols, avenanthramides, alkylresorcinols, and some essential fatty acids) and toxicant biactives (mycotoxins; aflatoxins, ocratoxin A, patulin, citrinin, cyclopiazonic acid, T-2, fumonisin, deoksinivalenol, and zearalenon) from the sources of selected fleshy fruits including temperate fruits (pome, stone, and berry fruits), citrus and tropical fruits, nuts, and from various cereals (and pseudocereals), pulses (e.g., legumes and edible beans). Each chapter reviews dietary sources, occurrences, chemical properties, desirable and undesirable health effects, antioxidant activity, evidentiary findings, applications as well as toxicity of the abovementioned bioactives and have been individually highlighted based on the fruit and cereal type. Fruit and Cereal Bioactives present a unique and unified data to the fruit and cereal chemistry from a biochemical standpoint.

ReferencesAndersen, B., and Thrane, U. 2006. Food-borne fungi in fruit and cereals and their production of mycotoxins. In Advances in Food Mycology. Vol. 571, 13752. Berlin: Springer-Verlag. Andersen, Q. M., and Markham, K. R. 2006. Flavonoids. Chemistry, Biochemistry, and Applications. Boca Raton, FL: CRC Press, Taylor & Francis. Astorg, P. 1997. Food carotenoids and cancer prevention: An overview of current research. Trends Food Sci Tech 8:40613.

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Beecher, G. R. 1999. Flavonoids in foods. In Antioxidant Food Supplements in Human Health, eds. L. Packer, M. Hiramatsu, and T. Yoshikawa. New York: Academic Press. Cheynier, V. 2005. Polyphenols in foods are more complex than often thought. Am. J. Clin. Nutr. 81 (Suppl): 2239. Crozier, A., Jaganath, I. B., and Clifford, M. N. 2006. Phenols, polyphenols and tannins: An overview. In Plant Secondary Metabolites, eds. A. Crozier, M. N. Clifford, and H. Ashihara, 124. Oxford: Blackwell Publishing, Ltd. Fennema, O. R. 1996. Flavonoids. In Food Chemistry. 3rd ed., 68196. New York: Marcel Dekker. Fraser, P. D., and Bramley, P. M. 2004. The biosynthesis and nutritional uses of carotenoids. Progress in Lipid Research 43: 22865. Gharras, H. E. 2009. Polyphenols: Food sources, properties and applicationsA review. Int J Food Sci and Technol. 44: 25128. Hertog, M. G. L., Feskens, E. J. M., Hollma, P. C. H., Katan, M. B., and Kromhout, D. 1993. Dietary antioxidant flavonoids and risk of coronary heart disease. The Zutphen Elderly Study. Lancet 342:100711. Ho, C. T., Rafi, M. M., and Ghai, G. 2007. Bioactive Substances: Nutraceuticals and Toxicants. In Fennema's Food Chemistry, 4th, eds. Srinivasan Damodaran, Kirk L. Parkin, Owen R. Fennema, CRC Press, Taylor & Francis, Boca Raton, FL, USA ISBN: 9780824723453, ISBN 10: 0824723457. 1160. Iamanaka, B. T., Taniwaki, M. H., Vicente, E., and Menezes, H. C. 2006. Fungi producing ochratoxin in dried fruits. In Advances in Food Mycology. Vol. 571, 18188. Berlin: Springer-Verlag. Jones, P. J., and AbuMweis, S. S. 2009. Phytosterols as functional food ingredients: Linkages to cardiovascular disease and cancer. Curr Opin Clin Nutr Metab Care 12 (2): 14751. Lee, J. H., and Schwartz, S. J. 2005. Analysis of carotenoids and chlorophylls in foods. In Methods of Analysis of Food Components and Additives, 17998. New York: Taylor & Francis Group. Merken, H. M., and Beecher, G. R. 2000. Measurement of food flavonoids by high performance liquid chromatography: A review. J Agric Food Chem 48 (3): 57995. Meskin, M. S., Bidlack W. R., Davies, A. J., Lewis, D. S., and R. K. Randolph. 2003. Phytochemicals: Mechanisms of Action. Boca Raton, FL: CRC Press. Omaye, S. T., Bidlack, W. R., Meskin, M. S., and D. K. W. Topham. 2000. Phytochemicals as Bioactive Agents. Lancaster, PA: Technomic Pub. Peterson, D. M. 2004. Barley tocolsEffects of milling, malting, and mashing. Cereal Chem 71 (1): 424. Ross, C. A., and Harrison, E. H. 2007. Vitamin A: Nutritional aspects of retinoids and carotenoids. In Handbook of Vitamins. 4th ed., eds. J. Zempleni, R. B. Rucker, D. B. McCormick, and J. W. Suttie, 139. Boca Raton, FL: Taylor & Francis Group. Ross, A. B., Kamal-Eldin, A., and Aman, P. 2004. Dietary alkylresorcinols: Absorption, bioactivities, and possible use as biomarkers of whole-grain wheat- and rye-rich foods. Nutr Rev 62 (3): 8195. Tokuolu, . 2001. The Determination of the Major Phenolic Compounds (Flavanols, Flavonols, Tannins and Aroma Properties of Black Teas. PhD Thesis. Department of Food Engineering, Bornova, Izmir, Turkey: Ege University. Vinson, J. A., Dabbagh, Y. A., Serry, M. M., and Jang, J. 1995. Plant flavonoids, especially tea flavonols, are powerful antioxidants using an in vitro oxidation model for heart disease. J Agric Food Chem 43: 28002.

2Health Promoting Effects of Cereal and Cereal ProductsJoseph M. Awika ContentsIntroduction................................................................................................................................................. 9 Cereal Consumption and Cancer.............................................................................................................. 10 Possible Mechanisms of Cereal Grains in Chemoprevention...............................................................11 Dietary Fiber Related Mechanisms. .................................................................................................11 Antioxidant Related Mechanisms....................................................................................................11 Phytoestrogen Related Mechanisms............................................................................................... 12 Mediation of Glucose Response..................................................................................................... 12 Cereal Grain Consumption and Cardiovascular Disease.......................................................................... 12 Cereal Grain Consumption in Obesity and Diabetes................................................................................ 13 Summary....................................................................................................................................................14 References..................................................................................................................................................14

IntroductionCereal grains are consumed as the primary source of energy by most humans. Consumption of whole/ unrefined cereal products is known to contribute significantly to health and chronic disease prevention. Whole cereal grains contain nutritionally significant quantities of dietary fiber, as well as various minerals and vitamins that are important for health. More recent evidence also indicates that cereals contain significant quantities of phytochemicals, like antioxidants and phytoestrogens, which may significantly contribute to reported health benefits of whole grain consumption. In most cases, these beneficial compounds are concentrated in outer layers (bran) of the grain (Table 2.1). Unfortunately, modern grain milling methods remove most of these compounds with the bran to produce refined endosperm fractions that are more appealing to consumers in most food applications. The refined grain products generally lack the health benefits that whole grains provide. At the moment, the vast majority of cereal products consumed around the world are made from refined grain. For example, in the United States, the Harris Interactive survey commissioned by the Grain Foods Foundation estimated that whole grain products constituted about 11% of total grain consumption in 2008. Additionally, only 10% of the U.S. population consumes the daily recommended whole grain intake of at least three servings per day. On the positive side, emerging strong links between unrefined grain-based diets and population health, coupled with public education, are renewing consumer interest in whole grain products. For example, various market trend data indicate that whole grain popularity is on the rise with consumers; between 2003 and 2008, the whole grain segment was among the fastest growing food product categories in the United States. The level of whole grain consumption in the United States in 2008 was 20% higher than it was in 2005. Efforts to promote whole grain consumption were until relatively recently not based on any strong epidemiological evidence of disease prevention (Slavin 1994), but mostly on recognized need for increased9

10Table 2.1


Antioxidant Activity and Dietary Fiber Content of Sorghum and Wheat Grain and BranaAntioxidant Activityb Sample Red wheat White sorghum Red sorghum Black sorghum Tannin sorghum CV %a

Bran Dietary Fiber (% db) Grain 12.6 6.3 10.3 9.8 11.1 Bran 47.6 38.3 43.9 45.3 44.5

Grain 10.6 9.8 53 104 240 3.2

Bran 36.3 30.1 230 378 890 4.3

b

Adapted from Awika, J. M., McDonough, C. M., and Rooney, L. W., Journal of Agricultural and Food Chemistry, 53(16), 623034, 2005; Awika, J. M., Rooney, L. W., Wu, X. L., Prior, R. L., and Cisneros-Zevallos, L., Journal of Agricultural and Food Chemistry, 51(23), 665762, 2003. mol TE/g, measured by the ABTS method.

fiber intake that was known to improve fecal bulk and intestinal transit time, and thus believed to improve gut health. However, in the recent past, numerous epidemiological and intervention studies from around the world have demonstrated significant health benefits directly linked to whole grain consumption (Jacobs et al. 2000). Cereal grain-based products have been linked to reduced incidences of some types of cancer (Bidoli et al. 1992; Slattery et al. 1997), cardiovascular disease (CVD; Liu et al. 1999; Nettleton et al. 2009; Tighe et al. 2007), diabetes and obesity (Fung et al. 2001).

Cereal Consumption and CancerEvidence linking grain consumption with cancer risk has been reported for some time, even though plausible mechanisms have been mostly speculative. Whole grain consumption is widely believed to help reduce cancer risk, whereas refined grain products have no beneficial effect. In fact, a few reports have linked increased consumption of some grains with an elevated risk of certain gastrointestinal cancers (Chen et al. 1993), even though such evidence could be attributed to other factors like aflatoxin (Isaacson 2005) that can be found in some grains, like corn, when grown in hot environments or handled improperly post harvest. Sorghum consumption has been particularly linked to reduced incidences of esophageal cancer in various parts of the world where this type of cancer was endemic, including parts of Africa, Iran, and China (Vanrensburg 1981). These findings were supported by epidemiological evidence linking sorghum and millet consumption with 1.43.2 times lower mortality from cancer of the esophagus in Sachxi Province of China (Chen et al. 1993). Interestingly, both authors reported no benefit or elevated risk of cancer of the esophagus with increased consumption of corn and wheat flour in these studies. The forms in which these grains were consumed in these regions were not reported. However, dietary patterns in these areas indicate that wheat, for example, is mostly consumed in a highly refined form in these areas. A case in point is China, where steamed bread, a major form in which wheat is consumed, is usually prized for whiteness and smooth texture, properties only possible with highly refined wheat flour. Such refined products have not been shown to contribute to chemoprevention. On the other hand the beneficial effects reported for sorghum consumption may be related to the fact that sorghum is mostly consumed with limited to no refining. Additional evidence also indicates that sorghum contains high levels of phytochemicals relative to other cereals (Awika et al. 2003). The sorghum phytochemicals may also have higher bioactivity than those found in other grains. For example, recent evidence demonstrates that some unique compounds in sorghum (e.g., 3-deoxyanthocyanins) may have stronger chemoprotective properties than their analogs from other plant sources (Yang, Browning, and Awika 2009). In the recent past, a flood of evidence (based on epidemiological and intervention studies) linking cereal grain consumption with reduced incidences of, especially, gastrointestinal cancer have emerged

Health Promoting Effects of Cereal and Cereal Products

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(Jacobs et al. 1998a; Kasum et al. 2001; Larsson et al. 2005; Levi et al. 2000; Schatzkin et al. 2008). In almost all cases, the positive benefits are only realized when grain is consumed in an unrefined form, or when cereal bran components are included in a diet. Thus it is safe to assume that the refined cereal endosperm products will not provide any meaningful health benefits beyond basic nutrition. For example, Larsson et al. (2005) reported a risk of 0.65 for colon cancer among those who consumed at least 4.5 servings of whole grain per day compared to those who consumed less than 1.5 servings. Levi et al. (2000) reported a significant reduction in the risk of oral, esophageal, and laryngeal cancer with increased consumption of whole grain as opposed to refined grain products. Numerous bodies of evidence that corroborate the link between whole grain consumption and gastrointestinal cancer are available in literature. Most of these investigations have, however, been conducted in developed countries. It is still not known how these data would translate to developing countries where malnutrition and presence of other confounding factors, like aflatoxin in grain, can be significant. This should be investigated since the developing countries consume a lot more cereal grain as a proportion of diet than the developed countries. Less clear is the link between whole grain consumption and some hormonally dependent cancers, such as breast cancer (La Vecchia and Chatenoud 1998). For example, a recent cohort study by Egeberg et al. (2009) failed to find a link between whole grain consumption and breast cancer risk among Danish postmenopausal women, similar to previous findings (Fung et al. 2005; Nicodemus, Jacobs, and Folsom 2001). On the other hand Kasum et al. (2001) reported that even though there was no statistical association between whole grain intake and endometrial cancer among postmenopausal women in general, a significant reduction in risk was observed when women who never used hormone replacement therapy were considered independently. In general, however, the link between breast and other hormonally dependent cancers and cereal grain consumption is weak. This may be due partly to the generally low levels and wide variation in phytoestrogens (usually lignans) in cereal grains. Additional evidence is needed in this regard.

Possible Mechanisms of Cereal Grains in ChemopreventionVarious mechanisms have been proposed for the effects of whole grain on cancer risk based on animal and in vitro model studies. Since the strongest evidence of whole grain consumption and cancer risk are for gastrointestinal cancer, it is believed cereal components may exert their effects via direct interaction with gastrointestinal epithelial cells. The mechanisms can be summarized into four broad and generally inclusive categories: dietary fiber related mechanisms, antioxidant related mechanisms, phytoestrogen related mechanisms, and mediation of glucose response (Slavin 2000).

Dietary Fiber Related MechanismsDietary fiber is believed to impart its beneficial effect by two mechanisms: (1) increasing fecal bulk and reducing intestinal transit time, thus limiting interaction of potential fecal mutagens with intestinal epithelium, and (2) fermentation of soluble fiber by colon microflora to produce short chain fatty acids like butyrate, propionate, and acetate, which lower intestinal pH and promote gut health by diminishing bile acid solubility and cocarcionogenicity, and also possibly via direct suppression of tumor formation by butyrate (McIntyre, Gibson, and Young 1993). Thus, different cereal products may impact chemoprotection via different mechanisms depending on their dietary fiber composition.

Antioxidant Related MechanismsOxidative damage can lead to chronic cell injury, which is one of the mechanisms that may lead to cancer (Klaunig et al. 1998). Whole grains are rich in antioxidant phenolics (e.g., ferulates and flavonoids), vitamins (e.g., vitamin E), minerals (e.g., selenium), and other components mostly concentrated in their bran and germ. These dietary antioxidants directly suppress oxidative damage by quenching potentially damaging free radicals generated by various metabolic processes. They are also known to suppress the

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growth of preformed cancer cells, which may contribute to elimination of cancer in early stages. Some of the antioxidants (e.g., selenium) are also cofactors of antioxidant enzymes, while others may enhance activity of protective phase II enzymes (Yang, Browning, and Awika 2009). For example, sorghum is an especially rich source of antioxidants (Table 2.1); this may partly explain the distinct chemoprotective properties against esophageal cancer reported for sorghum relative to corn or wheat.

Phytoestrogen Related MechanismsEstrogenic effects of cereals may be produced by lignans that are found in low quantities in cereal brans. These plant lignans (e.g., secoisolariciresinol) can be metabolized by intestinal microflora into mammalian lignans like enterodiol, which are estrogenic. Other authors have suggested that dietary fiber may also interrupt enterohepatic circulation of estrogen, leading to increased fecal estrogen secretion (Goldin et al. 1982).

Mediation of Glucose ResponseSince a link between the cause of obesity and cancer has been suggested, it is believed that whole grains, through their effect of slowing glycemic response and thus insulin secretion, may contribute to chemoprevention (Schoen et al. 1999). See the section near the end of this chapter about cereal grain consumption in obesity and diabetes for more detail.

Cereal Grain Consumption and Cardiovascular DiseaseCardiovascular disease (CVD) remains the leading cause of deaths in much of the developed world, and a major contributor to morbidity and health care costs. It has been long recognized that diets rich in unrefined grain or grain components, as well as dietary fiber can help significantly lower the risk for CVD (Trowell 1972), even though systemic evidence began emerging only in the latter part of the 1990s. A recent meta-analysis of several cohort studies estimated that an average of 2.5 servings of whole grain per day reduced the risk of CVD events by 21% compared to 0.2 servings/day of whole grain (Mellen, Walsh, and Herrington 2008). Evidence indicates that the beneficial effect of cereal grains on cardiovascular health may be related to bran components. For example, Jensen et al. (2004) reported that adding bran to a whole grain diet reduced coronary heart disease (CHD) risk by 30% compared to whole grain alone, which reduced the risk by 18% among male professionals aged 4075 years. The authors found that the added germ had no effect on CHD risk. Similar findings have been documented in various other studies. This type of evidence initially led to the assumption that the dietary fiber in the bran part of whole grain was primarily responsible for the beneficial effect. However, other studies have found that the benefit of whole grain consumption cannot be fully explained by their dietary fiber content alone (Liu et al. 1999). Other than soluble and insoluble dietary fiber, cereal bran contains a complex mixture of antioxidant molecules, phytoseterols, policosanols, phytoestrogens, trace minerals, vitamins, and other compounds that have been associated with positive cardiovascular outcomes in controlled studies. Effects of cereal dietary fiber components on cardiovascular health are well documented. However, the exact mechanisms involved are not very clear. Some studies have reported a higher effect of insoluble cereal fiber on cardiovascular health than soluble fibers (Lairon et al. 2005), while others have reported the opposite effect. However, such inconsistencies may be due to the simple fact that it is often difficult, if not impossible, to isolate the effect of various forms of dietary fiber in cereals on cardiovascular health. In general, there is an agreement that soluble dietary fiber increases viscosity of gastric content, reducing the rate of absorption of nutrients. This may improve glycemic response and consequently reduce insulin demand and improve the blood lipid profile. The soluble fibers may also exert their effect via partial fermentation into short chain fatty acids by colon microflora; reducing colon pH and thus reducing bile acid solubility and sterol reabsorption. Some short chain fatty acids, especially butyric and propionic acid, may also directly inhibit cholesterol biosynthesis.


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Cereal bran wax components, specifically phytosterols and policosanols have been reported in various studies to reduce cholesterol absorption and biosynthesis. For example, sorghum dry distiller grain hexane extracts were shown to significantly reduce cholesterol absorption by up to 17% and non-HDL plasma cholesterol by up to 70% in animal models (Carr et al. 2005). The authors attributed the unusually potent effect of sorghum lipid extracts to the relatively high policosanol content of sorghum bran. Phenolics and other antioxidants found in cereal bran are also believed to contribute to cardiovascular health by reducing inflammation and LDL oxidation, as well as improving endothelial function, and inhibiting platelet aggregation. Some studies have also implicated phenolic compounds in cholesterol reduction (Fki, Sahnoun, and Sayadi 2007; Parker et al. 1996). Phytoestrogens found in cereal bran (mostly lignans) are hypothesized to promote favorable vascular responses to stress as well as endothelium-modulated dilation by inhibiting platelet aggregation or platelet release of vasoconstrictors (Anderson et al. 2000; Slavin, Jacobs, and Marquart 1997). It seems that the net effect of whole grain diets on cardiovascular health is a result of synergistic and complex interactions of dietary fiber with various minor components in ways that are not yet fully understood. This may also explain why isolated cellulose fiber does not produce similar cardiovascular benefits as whole grain or cereal bran (Kahlon, Chow, and Wood 1999).

Cereal Grain Consumption in Obesity and DiabetesAppetite suppression and control is the single most important mechanism to regulate calorie intake and thus affect weight gain. Satiety (longer duration between meals) and satiation (lower meal energy intake) play key roles in appetite control and energy intake. Whole grain products are believed to influence satiety and satiation due, at least partly, to their effect on glycemic response. Unrefined grain products are digested and absorbed more slowly, resulting in smaller postprandial glucose responses and insulin demand on the pancreatic cells (Slavin, Jacobs, and Marquart 1997). By regulating insulin response, whole grain products may prevent problems associated with elevated blood insulin, including altered adipose tissue physiology and increased lipogenesis and appetite. Ludwig et al. (1999) reported that the high glycemic index (GI) foods may actually promote overeating in obese children. The authors reported that voluntary energy intake after a high GI meal was 53% higher than after a medium GI meal among obese teenage boys. On the other hand, Burton-Freeman and Keim (2008) reported that high GI meals resulted in greater satiety and suppression of hunger than low GI meals in obese women. The authors concluded that low GI diets may not be suitable for optimal appetite and satiety among overweight women. Such controversy is understandable given that satiety and GI are not by themselves precise measures of anything meaningful. Satiety is highly subjective and related to behavioral factors not fully understood. Additionally, GI in itself is highly variable depending on measuring conditions, among other factors, and its use as a predictor on the health impact of carbohydrate consumption remains very much questionable. Such variability have led some authors to propose doing away with the GI as such and evaluating meal quality based on individual and demonstrated merits like whole grain content (Sloth and Astrup 2006). All the same, glycemic response as a mechanism is useful in explaining some observations related to whole grain and dietary fiber intake. The reduced glycemic response of whole grain foods is partly attributed to the dietary fiber. Both soluble and insoluble dietary fiber found in whole grain products can provide a physical barrier to digestive enzymes, thus resulting in slow and sometimes incomplete digestion of starch. Indeed, it is known that whole grain products have higher type 1 resistant starch (physically inaccessible starch) than refined grain counterparts. The soluble part of dietary fiber may additionally increase gastric lumen viscosity that further slows digestion and macronutrient absorption. Another factor that may contribute to reduced insulin response is the reduced energy intake due to the bulking effect of dietary fiber that reduces energy density of a meal and increases satiation. However, dietary fiber alone does not explain the insulin response modulating properties of whole grain products. For example, long-term wheat bran consumption was shown to improve glucose tolerance better than pectin (Brodribb and Humphreys 1976). Other components concentrated in the bran and possibly germ, like antioxidants, vitamin E, and Mg, may also contribute to insulin sensitivity. Oxidative stress has been associated with reduced insulin-dependent glucose disposal and diabetic complications

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(Oberley 1988), whereas vitamin E and Mg may be involved in glucose metabolism (Slavin, Jacobs, and Marquart 1997). Whole grain may also affect satiation by insulin-independent mechanisms. For example, it has been shown that ingestion of whole grain products and cereal fiber may increase a secretion of the hormone, cholecystokinin, in the small intestine (Bourdon et al. 1999). This hormone is known to contribute to appetite suppression, as well as slowed gastric emptying and the inducement of satiety. Both clinical and observational studies show that an intake of whole grain is inversely associated with plasma biomarkers for metabolic syndrome and obesity, like C-peptide and leptin concentrations (Koh-Banerjee and Rimm 2003). Whole grain and fiber enhanced cereal products are reported to reduce overall calorie intake, and thus obesity, by suppressing appetite and via other mechanisms proposed above. For example, Hamedani et al. (2009) reported that breakfast cereal high in insoluble fiber significantly reduced short-term calorie intake in healthy individuals. Relatively recent epidemiological and some intervention studies seem to support the overall notion that whole grain consumption reduces obesity and metabolic syndrome. The Iowa Womens Health Study found that whole grain intake was inversely correlated with body weight and fat distribution (Jacobs et al. 1998b). Pereira etal. (1998) also reported that the whole grain intake was inversely related to BMI at a 7-year follow-up of the participants of the study. Another large study of health men and women, the Multi-Ethnic Study of Atherosclerosis (MESA), reported an inverse association between whole grain intake and obesity, along with insulin resistance, inflammation, and elevated fasting glucose or newly diagnosed diabetes (Lutsey et al. 2007).

SummaryEven though some controversies still remain, many studies support the link between whole grain consumption and overall health. However, most of these studies do not provide information on causality of the associations. Just like with other dietary components, it is very difficult to accurately pinpoint how and what components of a complex matrix like whole grain may impact specific health outcomes. However, given many of the rigorous studies show obvious benefits linked to whole cereal product consumption, even after correcting for various confounding variables, it is safe to conclude that whole grains should be actively promoted as a part of a healthy diet. Meanwhile more rigorous studies are needed to unravel the mechanisms by which whole grains impact health. This way, food product development efforts can be directed toward optimizing ingredient functionality to deliver health-promoting products that consumers can buy into en masse. This is especially important because no amount of preaching of health benefits will make consumers flock to a product consistently if the sensory appeal is substandard. Whole grain products, unfortunately, still largely suffer from the inferior sensory quality perception among the majority of consumers. Given that most human beings consume cereal grain-based products on a daily basis for primary nourishment, and will continue to do so into the foreseeable future, there is a tremendous opportunity to improve human health with a combination of innovative whole grain based products, public education, and cutting-edge research exposing the link between grain components andhealth.

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Lairon, D., N. Arnault, S. Bertrais, R. Planells, E. Clero, S. Hercberg, and M. C. Boutron-Ruault. 2005. Dietary fiber intake and risk factors for cardiovascular disease in French adults. American Journal of Clinical Nutrition 82 (6): 118594. Larsson, S. C., E. Giovannucci, L. Bergkvist, and A. Wolk. 2005. Whole grain consumption and risk of colorectal cancer: A population-based cohort of 60 000 women. British Journal of Cancer 92 (9): 18037. La Vecchia, C., and L. Chatenoud. 1998. Fibres, whole-grain foods and breast and other cancers. European Journal of Cancer Prevention 7: S258. Levi, F., C. Pasche, F. Lucchini, L. Chatenoud, D. R. Jacobs, and C. La Vecchia. 2000. Refined and whole grain cereals and the risk of oral, oesophageal and laryngeal cancer. European Journal of Clinical Nutrition 54 (6): 4879. Liu, S. M., M. J. Stampfer, F. B. Hu, E. Giovannucci, E. Rimm, J. E. Manson, C. H. Hennekens, and W. C. Willett. 1999. Whole-grain consumption and risk of coronary heart disease: Results from the Nurses Health Study. American Journal of Clinical Nutrition 70 (3): 4129. Ludwig, D., J. Majzoub, A. Al-Zahrani, G. Dallal, I. Blanco, and S. Roberts. 1999. High glycemic index foods, overeating and obesity Pediatrics 103: 16. Lutsey, P. L., D. R. Jacobs, S. Kori, E. Mayer-Davis, S. Shea, L. M. Steffen, M. Szklo, and R. Tracy. 2007. Whole grain intake and its cross-sectional association with obesity, insulin resistance, inflammation, diabetes and subclinical CVD: The MESA study. British Journal of Nutrition 98 (2): 397405. McIntyre, A., P. R. Gibson, and G. P. Young. 1993. Butyrate production from dietary fiber and protection against large-bowel cancer in a rat model. Gut 34 (3): 38691. Mellen, P. B., T. F. Walsh, and D. M. Herrington. 2008. Whole grain intake and cardiovascular disease: A meta-analysis. Nutrition Metabolism and Cardiovascular Diseases 18 (4): 28390. Nettleton, J. A., J. F. Polak, R. Tracy, G. L. Burke, and D. R. Jacobs. 2009. Dietary patterns and incident cardiovascular disease in the multi-ethnic study of Atherosclerosis. American Journal of Clinical Nutrition 90 (3): 64754. Nicodemus, K. K., D. R. Jacobs, and A. R. Folsom. 2001. Whole and refined grain intake and risk of incident postmenopausal breast cancer (United States). Cancer Causes & Control 12 (10): 91725. Oberley, L. W. 1988. Free radicals and diabetes. Free Radical Biology and Medicine 5:11324. Parker, R. A., R. L. Barnhart, K. S. Chen, M. L. Edwards, J. E. Matt, B. L. Rhinehart, K. M. Robinson, M. J. Vaal, and M. T. Yates. 1996. Antioxidant and cholesterol lowering properties of 2,6-di-t-butyl-4[(dimethylphenylsilyl)methyloxy]phenol and derivatives: A new class of anti-atherogenic compounds. Bioorganic & Medicinal Chemistry Letters 6 (13): 155962. Pereira, A., D. Jacobs, M. Slattery, K. Ruth, L. Van Horn, J. Hilner, and L. H. Kushi. 1998. The association of whole grain intake and fasting insulin in a biracial cohort of young adults: The CARDIA study. CVD Prevention 1: 23142. Schatzkin, A., Y. Park, M. F. Leitzmann, A. R. Hollenbeck, and A. J. Cross. 2008. Prospective study of dietary fiber, whole grain foods, and small intestinal cancer. Gastroenterology 135 (4): 11637. Schoen, R. E., C. M. Tangen, L. H. Kuller, G. L. Burke, M. Cushman, R. P. Tracy, A. Dobs, and P. J. Savage. 1999. Increased blood glucose and insulin, body size, and incident colorectal cancer. Journal of the National Cancer Institute 91 (13): 114754. Slattery, M. L., J. D. Potter, A. Coates, K. N. Ma, T. D. Berry, D. M. Duncan, and B. J. Caan. 1997. Plant foods and colon cancer: An assessment of specific foods and their related nutrients (United States). Cancer Causes & Control 8 (4): 57590. Slavin, J. L. 1994. Epidemiologic evidence for the impact of whole grains on health. Critical Reviews in Food Science and Nutrition 34 (56): 42734. Slavin, J. 2000. Mechanisms for the impact of whole grain foods on cancer risk. Journal of the American College of Nutrition 19 (3): 300S7S. Slavin, J., D. Jacobs, and L. Marquart. 1997. Whole-grain consumption and chronic disease: Protective mechanisms. Nutrition and CancerAn International Journal 27 (1): 1421. Sloth, B., and A. Astrup. 2006. Low glycemic index diets and body weight. International Journal of Obesity 30: S4751. Tighe, P., N. Vaughan, J. Brittenden, W. G. Simpson, W. Mutch, G. Horgan, G. Duthie, and F. Thies. 2007. Effect of increased consumption of whole grain foods on markers of cardiovascular disease risk in middle-aged healthy volunteers. Arteriosclerosis Thrombosis and Vascular Biology 27 (6): E56E56.


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Trowell, H. 1972. Ischemic heart disease and dietary fiber. American Journal of Clinical Nutrition 25: 92632. Vanrensburg, S. J. 1981. Epidemiologic and dietary evidence for a specific nutritional predisposition to esophageal cancer. Journal of the National Cancer Institute 67 (2): 24351. Yang, L. Y., J. D. Browning, and J. M. Awika. 2009. Sorghum 3-deoxyanthocyanins possess strong phase II enzyme inducer activity and cancer cell growth inhibition properties. Journal of Agricultural and Food Chemistry 57: 1797804.

Part II

Chemistry and Mechanisms of Beneficial Bioactives in Fruits and Cereals

3Phytochemicals in Cereals,Pseudocereals, and PulsesClifford Hall III and Bin Zhao ContentsIntroduction............................................................................................................................................... 22 Phytochemicals-Structural Characteristics............................................................................................... 22 Monophenols and Phenolic Acids. ....................................................................................................... 22 Tocopherols and Tocotrienols......................................................................................................... 22 Phenolic Acids................................................................................................................................ 23 Alkylresorcinols and Alkenylresorcinols............................................................................................. 25 Flavonoids............................................................................................................................................ 26 Antioxidant Activity....................................................................................................................... 27 Health Benefits. ............................................................................................................................... 28 Other Phytochemicals.......................................................................................................................... 29 Carotenoids..................................................................................................................................... 29 Phytosterols. .................................................................................................................................... 30 Summary......................................................................................................................................... 30 Phytochemicals from Cereals and Pseudocereals..................................................................................... 30 Defining Cereals and Pseudocereals.................................................................................................... 30 Cereals..................................................................................................................................................31 Barley...............................................................................................................................................31 Phenolics......................................................................................................................................... 32 Corn................................................................................................................................................ 35 Oats..................................................................................................................................................41 Rice................................................................................................................................................. 45 Rye.................................................................................................................................................. 49 Wheat.............................................................................................................................................. 55 Pseudocereals....................................................................................................................................... 59 Amaranth and Quinoa......................................................................................................................61 Phytochemicals from Pulses: Edible beans and Legumes........................................................................ 62 Dry Peas............................................................................................................................................... 63 Tocopherol and Carotenoids........................................................................................................... 63 Phenolic Compounds...................................................................................................................... 63 Other Components.......................................................................................................................... 64 Antioxidant Activity....................................................................................................................... 64 Dry Bean.............................................................................................................................................. 65 Tocopherol...................................................................................................................................... 65 Phenolic Compounds...................................................................................................................... 65 Other Components.......................................................................................................................... 66 Antioxidant Activity....................................................................................................................... 66 Future Direction........................................................................................................................................ 67 References................................................................................................................................................. 6721

22


IntroductionPhytochemicals are simply bioactive plant substances that provide a health benefit. Many of these compounds at one time were considered antinutrients. However, an extensive study of the phytochemicals (e.g., phenolics, carotenoids, tocopherols) has resulted in the discovery of many health benefits. Furthermore, the usefulness of these components as food additives has been demonstrated. In this chapter, the phytochemicals from cereals (and pseudocereals) and pulses (e.g., legumes and edible beans) will be presented. Due to the diverse functionality and chemical and structural makeup of the phytochemicals, only a small number of phytochemicals will be highlighted in this chapter. The phytochemicals of interest include simple phenols, polyphenolics, phenolic acid, carotenoids, and sterols. Specific focus on the composition of phytochemicals from the various sources, effects of processing on the phytochemicals, and antioxidant activity of the phytochemicals will be highlighted. In addition, information will be presented regarding structural features of the general classes of phytochemicals. Methods for the isolation and characterization of the phytochemicals will not be presented in detail in this chapter. The author suggests that the review of the referenced literature will be of value in this regard. Important references prior to 2000 will be presented; however, the chapter material will cover research primarily from 2000 to 2007. Hall (2001, 2003) reported reviews on phytochemicals prior to 2000, and recent reviews by Awika and Rooney (2004) and Dykes and Rooney (2006) highlighted phytochemicals in several cereals, thus the reader is directed to these reviews. The authors of this chapter recognize the efforts of many researchers in the phytochemical area; however, not all of the research could be reported in this review.

Phytochemicals-Structural CharacteristicsMonophenols and Phenolic Acids Tocopherols and TocotrienolsTocopherols and tocotrienols (tocols; Figure 3.1) are a group of monophenols that have vitamin E and antioxidant activities. The antioxidant activity of the tocols has been widely documented and will not be extensively described in this chapter. However, the phenolic hydrogen at the C6 position can participate in chain breaking mechanisms, including radical scavenging (Figure 3.2). Tocopherols and tocotrienols have been well characterized as antioxidants (Yoshida, Niki, and Noguchi 2003). The research on the health benefits of tocopherols and tocotrienols is conflicting. However, some studies have supported the health benefits. The role of tocols in disease prevention has been attributed to the antioxidant activity where the tocotrienols appear to have the most benefit (Qureshi et al. 1997, 2000; McIntyre et al. 2000; Packer, Weber,R1 HO CH3 R2 R3 Tocopherols R1 CH3 CH3 H H R2 CH3 H CH3 H R3 CH3 CH3 CH3 CH3 O R2 R3 R1 CH3 CH3 H H O Tocotrienols R2 CH3 H CH3 H R3 CH3 CH3 CH3 CH3 HO CH3 R1

Figure 3.1 The monophenols tocopherol and tocotrienols.

24OH R2 R1

Fruit and Cereal Bioactives: Sources, Chemistry, and ApplicationsOH R2 R1

COOH Benzoic acid derivativesp-Hydroxy benzoic acid Vanillic acid Syringic acid Dihydroxybenzoic acid Gallic acid R1 = H, R2 = H R1 = H, R2 = OCH3 R1= OCH3, R2 = OCH3 R1 = OH, R2 = H R1 = OH, R2 = OH

CH

CH COOH

Cinnamic acid derivativesp-Coumaric acid Ferulic acid Sinapic acid Ca eic acid R1 = H, R2 = H R1 = H, R2 = OCH3 R1= OCH3, R2 = OCH3 R1 = OH, R2 = H

OH OCH3 HO O HO O HO O

O H3CO OH 8-8'-ferulic acid

OH OCH3

O OH

O

CH3

4-O-5'-ferulic acid

Figure 3.3 Common phenolic acids in cereals, pseudocereals, and legumes, including examples of diferulic compounds associated with cell walls. (Adapted from Bunzel, M., Ralph, J., Marita, J., Hatfield, R., and Steinhart, H., J. Agric. Food Chem., 48, 31669, 2000; Bunzel, M., Ralph, J., Marita, J., Hatfield, R., and Steinhar, H., J. Sci. Food Agric., 81, 65360, 2001.)OH OH Hydrogen Abstraction O OH Electron Rearrangement O H O

OH OCH3 Hydrogen Abstraction

O OH No H-bonding

Figure 3.4 Intramolecular hydrogen bonding of ortho substituted phenols. (Adapted from Baum, B., and Perun, A., Soc. Plastics Eng. Trans., 2, 2507, 1962.)

para substitutions in the phenolic acids give mixed antioxidant results. The quinic acid substitution (i.e., chlorogenic acid) at the para position was equally effective as caffeic acid in controlling oxidation. Structurally, the only difference between the molecules was the para substitute; thus, the authors concluded that the acid proton of caffeic acid had little effect on the antioxidant activity of the cinnamic acid derivatives (Pratt and Birac 1979). In contrast, vinyl substituted phenolic acids (i.e., cinnamic acid derivatives) were more effective as antioxidants then the benzoic acid derivatives (Pratt and Hudson 1990; Cuvelier, Richard, and Berset 1992). Cuvelier, Richard, and Berset (1992) suggested that the vinyl

Phytochemicals in Cereals,Pseudocereals, and PulsesR1 CH3 R2 R3 Hydrogen abstraction R1 CH3 R2 R3 LOO trapping O R2 R1 CH3 O R3 OOL O O

23

HO

O

Figure 3.2 Hydrogen donation and radical scavenging activity of monophenols.

and Rimbach 2001; Wu et al. 2005; Nakagawa et al. 2007). Halliwell, Rafter, and Jenner (2005) reported that the benefits might be related to the affects of these components in the gastrointestinal tract (GI) and the prevention of radical species formation in the GI tract. However, these authors did state that the mechanisms of action were still not clear. The anticarcinogenic activity of tocotrienols has been reported (Mizushina et al. 2006). For additional information on the health benefits of tocotrienols from rice see Hall (2003).

Phenolic AcidsSimilar to tocols, the phenolic hydrogen(s) of phenolic acids (Figure 3.3) contribute antioxidant activity. Phenolic acids tend to be located on the out layers (aleurone, pericarp) of cereals (Sosulski, Krygier, and Hogge 1982; Hutzler et al. 1998; Naczk and Shahidi 2006) in contrast to the higher tocol levels in the germ (Barnes 1983). Thus, the benefits of phenolic acid would be realized if the outer portions of the grain were not removed prior to the consumption. Phenolic acids can act as antioxidants through a number of different mechanisms. The chain breaking mechanisms, which include hydrogen donation and radical acceptor (i.e., radical scavenging activity; Scott 1985), are the most likely means by which phenolic acids act as antioxidants (Figure 3.2). Variations in the antioxidant activity of individual phenolic acids have been documented (Pratt and Birac 1979; Pratt and Hudson 1990; Cuvelier, Richard, and Berset 1992). These authors observed key structureactivity relationships that accounted for the differences in antioxidant activities. The dihydroxy forms of the phenolic acids have better antioxidant activity due the addition of a second hydroxyl group in the ortho position. This statement can be supported by the observation of Pratt and Birac (1979) that caffeic acid had better antioxidant than the monohydroxy phenolic acids (i.e., ferulic acid and -coumaric acid). The improved antioxidant activity of caffeic was likely due to the intramolecular hydrogen bonding (Figure3.4) that can occur in ortho substituted phenols (Baum and Perun 1962). A third hydroxyl group further enhances the antioxidant activity as trihydroxybenzoic acid (i.e., gallic acid) and is a better antioxidant than 3,4-dihydroxy-benzoic acid (i.e., protocatechuic acid; Pratt and Birac 1979). The

Phytochemicals in Cereals,Pseudocereals, and Pulses

25

group could enhance the resonance stability of the phenoxyl radical whereby improving the antioxidant activity. Thus, by understanding the above relationships one can predict the antioxidant potential of a plant material containing phenolic acids.

Alkylresorcinols and AlkenylresorcinolsAlkylresorcinols and alkenylresorcinols have a 1,3-dihydroxybenzene base structure and an aliphatic substitution at carbon five of the ring (Figure 3.5). The aliphatic group typically has between 17 and 25 carbons (Kozubek and Tyman 1995, 1999; Ross et al. 2001; Ross, Kamal-Eldin, and Aman 2004). When the aliphatic group is unsaturated, the compounds are generically referred to as alkenylresorcinols. However, the alkylresorcinols (i.e., saturated aliphatic group) are the most common. Furthermore, these compounds are concentrated in the bran fractions of many cereal grains and may contribute to the health benefits attributed to whole grain consumption. The interest in this group of compounds stems from the reported anticarcinogenic, antimicrobial, and antioxidant properties (Singh et al. 1995; Gasiorowski et al. 1996; Kozubek and Tyman 1999; Slavin et al. 2001). For a summary of the reported benefits, see the review by Ross, Kamal-Eldin, and Aman (2004). The bioavailability of the alkylresorcinols shows that about 60% are absorbed by the human ileostomy (Ross et al. 2003a), but only small amounts are present in the plasma (Linko et al. 2002). However, higher alkylresorcinols concentrations were present in erythrocyte membranes, which appear to be a site for alkylresorcinol storage, than plasma membranes (Linko and Adlercreutz 2005). These authors also noted that the longer chained alkylresorcinols were incorporated into the erythrocyte membrane at higher concentrations than short-chained alkylresorcinols. Much of the intact alkylresorcinols and metabolites 3-(3,5-dihydroxyphenyl)-1-propanoic acid and 1,3-dihydroxybenzoic acid were found in urine (Ross, Aman, and Kamal-Eldin 2004). The reader is encouraged to read the review written by Ross et al. (2004c) for more information on alkylresorcinol structural chemistry, including metabolites. The antioxidant function of alkylresorcinols and alkenylresorcinols has not been fully characterized. Compounds with the substitutions at the meta position to the hydroxyl on the benzene ring typically have poor antioxidant activity (Miller and Quackenbush 1957). Yet, several researchers have reported antioxidant effects of the alkylresorcinols in model test systems (Nienartowicz and Kozubek 1995; Winata and Lorenz 1996; Hladyszowski, Zubik, and Kozubek 1998; Litwinienko, Kasprzycka-Guttman, and Jamanek 1999). Kamal-Eldin et al. (2001) evaluated hydrogen donating and peroxy radical scavenging activity of these compounds and found very poor antioxidant activities. In fact, based on the adherence to general antioxidant definition that the compounds must be effective at low concentrations, they concluded thatR

HO R C15H31 C17H35 C19H39 C21H43 C23H47 C25H51 C19H37 Acronym (C15:0) (C17:0) (C19:0) (C21:0) (C23:0) (C25:0) (C19:1)

OH N ame 5-n-pentadecylresorcinol 5-n-heptadecylresorcinol 5-n-nonadecylresorcinol 5-n-heneicosylresorcinol 5-n-tricosylresorcinol 5-n-pentacosylresorcinol 5-

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Fruit and Cereal Bioactives