Table Of ContentS E C O N D E D I T I O N
Frying of Food
Oxidation, Nutrient and Non-Nutrient
Antioxidants, Biologically Active
Compounds, and High Temperatures
Edited by
Dimitrios Boskou
Ibrahim Elmadfa
Boca Raton London New York
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Library of Congress Cataloging-in-Publication Data
Frying of food : oxidation, nutrient and non-nutrient antioxidants, biologically active
compounds and high temperatures, second edition / [edited by] Dimitrios Boskou,
Ibrahim Elmadfa. -- 2nd ed.
p. cm.
Includes bibliographical references and index.
ISBN 978-1-4398-0682-1 (hardback)
1. Oils and fats, Edible--Effect of temperature on. 2. Frying. I. Boskou, Dimitrios. II.
Elmadfa, I.
TP670. F79 2010
664--dc22 2010043667
Visit the Taylor & Francis Web site at
http://www.taylorandfrancis.com
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Contents
Preface........................................................................................................................v
Editors ......................................................................................................................vii
Contributors List .......................................................................................................ix
Chapter 1 Fat and Nutrition ..................................................................................1
Ibrahim Elmadfa and Margit Kornsteiner-Krenn
Chapter 2 Oxidation Products and Metabolic Processes ....................................23
Mary N. Omwamba, William E. Artz, and Symon M. Mahungu
Chapter 3 Free Radicals in Biological and Food Systems ..................................49
Malgorzata Nogala-Kalucka and Aleksander Siger
Chapter 4 Changes in Nutrients, Antinutritional Factors, and
Contaminants at Frying Temperatures ...............................................71
Jan Pokorný and Jana Dostálová
Chapter 5 Enzymes and Thermally Oxidized Oils and Fats ............................105
Francisco J. Sánchez-Muniz, Juana Benedi, Sara Bastida,
Raul Olivero-David, and Maria J. González-Muñoz
Chapter 6 Determination of Oxidation Compounds and Oligomers by
Chromatographic Techniques ..........................................................157
M. Carmen Dobarganes, Gloria Márquez-Ruiz,
Susana Marmesat, and Joaquín Velasco
Chapter 7 Nutrient Antioxidants and Stability of Frying Oils
(Tocochromanols, β-Carotene, Phylloquinone, Ubiquinone 50,
and Ascorbyl Palmitate) ...................................................................177
Karl-Heinz Wagner and Ibrahim Elmadfa
Chapter 8 Nonnutrient Antioxidants and Stability of Frying Oils....................199
Dimitrios Boskou
iii
iv Contents
Chapter 9 Phytosterols and Frying Oils ............................................................225
Georgios Blekas and Dimitrios Boskou
Chapter 10 Chemical and Biological Modulations of Frying Fats—Impact
on Fried Food ...................................................................................251
Karl-Heinz Wagner and Ibrahim Elmadfa
Chapter 11 Food Hazards Associated with Frying .............................................265
George Boskou and Nikolaos K. Andrikopoulos
Index ......................................................................................................................311
Preface
In the last three decades there has been an interest in the relationship of dietary
antioxidants and other bioactive ingredients to the possible prevention of a number
of diseases, in the etiology of which oxidation mechanisms are involved. As a result,
naturally occurring nutritive and nonnutritive antioxidants have become a major
area of scientific research. In the fields of nutrition and biosciences, phytochemicals
such as phenols and certain hydrocarbons are now examined and discussed as food
antioxidants. In addition, changes in lifestyles in the modern world have triggered
a growing awareness that particular ingredients in foods may favorably modify diet-
related problems. This requires that valuable constituents of food are preserved dur-
ing processing. It is, therefore, interesting to examine the frying of food from the
point of view of changes due not only to triacylglycerols but also to non-glyceride
components that are also of biological importance.
Among the various biologically active ingredients present in oils and fats, anti-
oxidant vitamins seem to be very important. However, other minor constituents
such as phytosterols, phospholipids, and certain hydrocarbons probably affect the
performance of heated oil and the nutritional value of fried food. Some of these
minor constituents, such as phytosterols, carotene, and squalene may be categorized
as “functional.” Finally, polar phenolic compounds, which naturally occur in cer-
tain oils or may be obtained from herbs, spices, or other natural sources, have been
shown to have an impact on the stability of oils at high temperatures and may influ-
ence the rate of oxidation of nutrients.
This new edition of Frying of Food deals with some important chemical, bio-
chemical, and nutritional aspects of frying. Frying is a rapid and convenient method
to produce a palatable product with favorable color and flavor; but during frying,
many changes take place and breakdown products are formed. The deterioration of
the fat at elevated temperatures is influenced by various factors, such as the nature of
the cooking fat, the conditions of frying, the kind of heat transfer, the fryer removal
constructions, and the use of antioxidants and other additives. Most of these factors
have been discussed in detail, and information can be found in excellent reviews
already available in the literature. This book concentrates mainly on the nature of
the heated fat, the presence of oxidation retardants, especially those naturally occur-
ring in oils, and the stabilization of frying oils by novel antioxidants obtained from
natural sources. From this point of view, frying oil is not seen just as a medium to fry
food for many frying operations, but also as a source of antioxidants and bioactive
ingredients that may have a beneficial health effect. Other issues addressed, related
also to minor constituents, are interactions between frying oils and natural compo-
nents present in food and substances formed during frying. This feature, the focus on
minor constituents and their role in the performance of frying oil and its biological
value, sets this book significantly apart from others in the field.
Specific topics examined in the book are fat and nutrition, oxidation products
and metabolic processes, formation of radicals and protection mechanisms in vitro
v
vi Preface
and in vivo, changes in nutrients due to frying, high temperatures and antinutritional
factors, enzymes and digestion of thermally oxidized oils and fats, determination of
oxidation compounds and polymers, nutrients and nonnutrient antioxidants, healthy
stable oils rich in oxidation inhibitors, frying oils as sources of natural antioxidants,
phytosterols and their effect on the performance of a frying oil, strategies to reduce
trans fatty acids in fried food, phytosterol oxidation products, food hazards associ-
ated with frying and, finally, critical control points, preventive measures, and safety
and reliability during frying.
It is hoped that all those interested in the frying of food will find this an essential
reference book. It is also anticipated that some readers will recognize that the book
not only presents current facts about the frying of food but also tracks some lines for
future research.
Dimitrios Boskou
Ibrahim Elmadfa
About the Editors
Dimitrios Boskou, Ph.D., earned his doctorate in chemistry from the School of
Chemistry, Aristotle University of Thessaloniki, Thessaloniki, Greece, his PhD
degree from the University of London, and his Doctor of Science degree from
the School of Chemistry, Aristotle University. He served as an assistant, lecturer,
assistant professor, associate professor, professor, and head of the Laboratory of
Food Chemistry, Aristotle University, from 1970 to 2006. From 1986 to 1998 he
was a member of the IUPAC Oils, Fats and Derivatives Commission; from 1995
to 2005 he served as a member of the Supreme Chemical Council; and since
1995 he has been a member of the Scientific Committee on Food of the European
Commission and member and expert of the Food Additives Panel of the European
Food Safety Authority.
Dr. Boskou has written more than 85 published papers and reviews and authored
and edited five books (Olive Oil, AOCS Press, 1996; Frying of Food, Technomic
Publishing Co., 1999; Olive Oil, Second Edition, AOCS Press, 2006; Natural
Antioxidant Phenols, Research Signpost, 2006; Olive Oil, Minor Constituents,
and Health, 2009, Taylor & Francis). He was lead author of more than 10 chapters
in books related to heated fats, natural antioxidants, and olive oil chemistry. He
has contributed to international scientific encyclopedias and the Lexicon of Lipid
Nutrition, a joint IUPAC/IUNS work.
Ibrahim Elmadfa, Ph.D., is currently president of the International Union of
Nutritional Science (IUNS), vice-president of World Public Health Nutrition
Association (WPHNA) and president of the Austrian Nutrition Society. He is trained
in food science and nutritional sciences. He earned his PhD degree (1970) and
habilitation (1975) in human nutrition at the University of Giessen, Germany. He
served as lecturer and assistant professor (1971–1979) and professor (1980–1990) of
human nutrition at the University of Giessen. Since 1990 he has been professor for
human nutrition and director of the Institute of Nutritional Sciences at the University
of Vienna
He served as a scientific expert to the European Commission (1995–2000) and as
a member of the Scientific Committee on Food (different functions). He is a member
of Codex Alimentarius Austria (Novel Food) and the National Nutrition Committee.
He is a member of the WHO Nutrition Guidance Expert Advisory Group (NUGAG)
and the International Advisory Council of WHO Global Non-Communicable Disease
Network (NCDnet).
His main research interests include nutrient requirements in health and disease,
bioavailability of nutrients; nutrition and immune function, food safety and quality
and monitoring of nutrition and health status.
vii
viii About the Editors
Prof. Elmadfa is editor-in-chief of Annals of Nutrition and Metabolism and
Forum Nutrition (since 2000) and editorial board member of several scientific jour-
nals. He has published more than 400 papers in international scientific journals and
is editor and author/co-author of 24 books and reports and several book chapters. He
was coordinator and author of the Austrian Nutrition Report 1998, 2003 and 2008 as
well as the European Nutrition and Health Report 2004 and 2009.
Contributors List
Nikolaos K. Andrikopoulos George Boskou
Laboratory of Food Chemistry– Department of the Science of
Biochemistry–Physicochemistry Dietetics–Nutrition
Department of the Science of Harokopio University
Dietetics–Nutrition Athens, Greece
Harokopio University
Athens, Greece
M. Carmen Dobarganes
Instituto de la Grasa (CSIC)
William E. Artz
Department of Food Characterization
Department of Food Science and
and Quality
Human Nutrition
Sevilla, Spain
University of Illinois
Urbana, Illinois
Jana Dostálová
Sara Bastida Department of Food Chemistry
Departamento de Nutrición y and Analysis
Bromatología I (Nutrición) Prague Institute of Chemical
Facultad de Farmacia Technology
Universidad de Alcalá Prague, Czech Republic
Madrid, Spain
Juana Benedi Ibrahim Elmadfa
Departamento de Farmacología Department of Nutritional
Universidad Complutense de Madrid Sciences
Madrid, Spain University of Vienna
Vienna, Austria
Georgios Blekas
Laboratory of Food Chemistry and
Maria J. González-Muñoz
Technology
Departamento de Nutrición,
School of Chemistry
Bromatología y Toxicología
Aristotle University of Thessaloniki
Universidad de Alcalá
Thessaloniki, Greece
Madrid, Spain
Dimitrios Boskou
Laboratory of Food Chemistry and Margit Kornsteiner-Krenn
Technology Department of Nutritional
School of Chemistry Sciences
Aristotle University of Thessaloniki University of Vienna
Thessaloniki, Greece Vienna, Austria
ix
x Contributors List
Symon M. Mahungu Mary N. Omwamba
Department of Dairy and Food Department of Dairy and Food
Science and Technology Science and Technology
Egerton University Egerton University
Egerton, Kenya Egerton, Kenya
Jan Pokorný
Susana Marmesat Department of Food Chemistry and
Instituto de la Grasa (CSIC) Analysis
Department of Food Characterization Prague Institute of Chemical
and Quality Technology
Sevilla, Spain Prague, Czech Republic
Francisco J. Sánchez-Muniz
Gloria Márquez-Ruiz
Departamento de Nutrición y
Instituto de Ciencia Tecnologia de
Bromatología I (Nutrición)
Alimentos y Nutrition (CSIC)
Facultad de Farmacia
Sevilla, Spain
Universidad de Alcalá
Madrid, Spain
Malgorzata Nogala-Kalucka
Department of Biochemistry and Food Aleksander Siger
Analysis Department of Biochemistry and Food
Faculty of Food Science and Analysis
Nutrition Faculty of Food Science and Nutrition
Poznan University of Life Poznan University of Life Sciences
Sciences Poznan, Poland
Poznan, Poland
Joaquín Velasco
Instituto de la Grasa (CSIC)
Raul Olivero-David Department of Food Characterization
Departamento de Nutrición y and Quality
Bromatología I (Nutrición) and Sevilla, Spain
Departamento de Nutrición,
Bromatología y Toxicología Karl-Heinz Wagner
Facultad de Farmacia Institute of Nutritional Sciences
Universidad de Alcalá University of Vienna
Madrid, Spain Vienna, Austria
