Food Antioxidants

325 Pages·1990·9.99 MB·English

by  M. H. Gordon (auth.)

FOOD ANTIOXIDANTS
ELSEVIER APPLIED FOOD SCIENCE SERIES
Biotechnology Applications in Beverage Production
C. CANTARELLI and G. LANZARINI
Progress in Sweeteners
T. H. GRENBY (Editor)
Food Refrigeration Processes: Analysis, Design and Simulation
A. C. CLELAND
Development and Application of Immunoassay for Food Analysis
J. H. R. RITTENBURG (Editor)
Microstructural Principles of Food Processing and Engineering
J. M. AGUILERA and D. W. STANLEY
Forthcoming titles in this series:
Food Gels
P. HARRIS (Editor)
Food Irradiation
S. THORNE
FOOD ANTIOXIDANTS
Edited by
B. J. F. HUDSON
Honorary Research Fellow and Consultant,
Department of Food Science and Technology,
University of Reading, UK
ELSEVIER APPLIED SCIENCE
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WITH 48 TABLES AND 44 ILLUSTRATIONS
© 1990 ELSEVIER SCIENCE PUBLISHERS LTD
Sof tcover reprint of the hardcover I st edition 1990
British Library Cataloguing in Publication Data
Food antioxidants.
1. Processed food. Antioxidants
I. Hudson, B. J. F.
664'.06
ISBN-I3:978-94-010-6824-6
Library of Congress Cataloging-in-Publication Data
Food antioxidants/edited by B. J. F. Hudson.
p. cm.
Includes bibliographical references.
ISBN-I3:978-94-0 10-6824-6 e-ISBN -13: 978-94-009-0753-9
DOl: 10.1007/978-94-009-0753-9
1. Antioxidants. 2. Food additives. 3. Antioxidants-Physiological effect.
I. Hudson, B. J. F.
[DNLM: 1. Antioxidants-pharmacology. 2. Food Additives-pharmacology_
WA 712 F6858j
TX553.A73F66 1990
664' .028--dc20
DNLM/DLC 89-25875
for Library of Congress CIP
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PREFACE
Antioxidants are present naturally in virtually all food commodities,
providing them with a valuable degree of protection against oxidative
attack. When food commodities are subjected to processing, such
natural antioxidants are often depleted, whether physically, from the
nature of the process itself, or by chemical degradation. In conse
quence, processed food products usually keep less well than do the
commodities from which they originated. Ideally, food producers
would like them to keep better. This objective can often be achieved
by blending natural products rich in antioxidants with processed foods,
or by using well recognised antioxidants as food additives.
In order to understand their action, and hence to apply antioxidants
intelligently in food product formulation, some knowledge of the
mechanisms by which they function is necessary. This is complex and
may rely on one or more of several alternative forms of antioxidative
intervention. Accordingly, the various mechanisms that may be
relevant are discussed in Chapter 1, in each case including the
'intervention' mechanism.
When present in, or added to, foods antioxidants are functional in
very small quantities, typically, perhaps, at levels of 0·01 % or less.
Indeed, at higher concentrations, since they themselves are susceptible
to oxidation, they can behave as pro-oxidants. Identification and
estimation of quantities of this order demand sophisticated, precise
and unambiguous analytical techniques. It is important, both for
quality assurance and to ensure that the regulations that apply in
different countries and for different classes of food products are
complied with. Chapter 2 provides comprehensive information on
suitable analytical techniques. It also discusses a variety of methods
available for evaluating the efficacy of antioxidants for foods.
A topic that seldom receives adequate attention in food antioxidant
v
VI PREFACE
reviews is dealt with in Chapter 3. This serves to answer the
question-'What happens chemically to antioxidants when they are in
the process of exerting their protective function?' It is insufficiently
recognised that, throughout the period during which they are extend
ing the shelf-life of a food product, they are undergoing chemical
changes. Sometimes the products of these changes are themselves still
active as antioxidants, sometimes not. As the shelf-life comes to its
close there may be little or none of the original antioxidant left. Such
considerations are relevant both to the biological evaluation of
antioxidants and to analytical methodology, especially if the food
product under investigation, though still acceptable in terms of quality,
is no longer fresh but is approaching the end of its shelf-life.
The benefits, from the quality standpoint, that can arise from the
inclusion of antioxidants in foods, are dealt with in Chapters 4 and 5.
Chapter 4 is concerned with the practical benefits arising from the uses
of three very important groups of natural products, the tocopherols,
carotenoids and ascorbic acid and its derivatives. Skilled technology
has provided, in these cases by chemical synthesis, the more significant
of these substances in forms identical with those found in nature.
Though they function by different mechanisms, all three have proved
highly effective in appropriate situations.
Not all natural antioxidants have proved to be commercially viable.
However, because many of those so far unexploited are virtually
ubiquitous, especially in plant products, including most, if not all, food
plants, they must receive attention in this text. Chapter 5 discusses the
properties and relevance of these natural antioxidants, with special
attention to the ftavonoids.
In considering the biological aspects of food antioxidants, one must
be concerned with the part they play in the living organism. So far as
food is concerned this means after ingestion of the food products in
which they are present. Chapter 6, again mainly stressing naturally
occuring antioxidants, shows that they have positive roles in maintain
ing the health of the organism and guarding against the depletion of
essential nutrients. We return here to mechanisms, not only those of
the types reviewed in Chapter 1, but adding a biological dimension
which now becomes highly relevant. Chapter 6 also seeks to emphasise
the relationship between antioxidant and vitamin activity, especially in
vitamins A, C and E but perhaps also extending to the ftavonoids,
which once included 'Vitamin P'.
Finally, Chapter 7 deals with toxicity. Few, if any, food components
PREFACE vii
can be given unreservedly a 'clean bill of health' in this respect. If no
adverse effects can be observed at low levels, one has only to increase
intake sufficiently, if not always realistically, to produce undesirable
effects. If acute toxicity trials show no adverse reactions, a component
or additive may show chronic effects when ingested over a very long
period. This applies both to 'natural' and 'artificial' antioxidants as
much as to other additives. Toxicity data concerning the most
important of the commercially available products in both of these
classes of food additives are presented.
This text does not attempt to provide a complete or detailed
coverage of the subject. The informed reader may well detect gaps in
the presentaion. It does, however, offer an up-dated broad overview
of antioxidants integral to, or used as additives for, food products,
stressing natural as distinct from artificial classes. The continuing trend
towards new forms of food processing, long-term food storage, added
to informed consumer concern, ensures that these protective food
ingredients will assume increasing importance to the food industry, in
food distribution and at the point of sale.
My special thanks are due to the ten authors who have contributed
specialised material for this volume and to the publishers for their
patience and encouragement.
B. J. F. HUDSON
CONTENTS
Preface. v
List of Contributors xi
1. The Mechanism of Antioxidant Action in vitro 1
M. H. GORDON
2. Detection, Estimation and Evaluation of Antioxidants in Food
Systems . 19
S. P. KOCHHAR and J. B. ROSSELL
3. Chemistry and Implications of Degradation of Phenolic Antioxidants 65
K. KIKUGAWA, A. KUNUGI and T. KUREcm
4. Natural Antioxidants Exploited Commercially 99
P. SCHULER
5. Natural Antioxidants not Exploited Commercially. 171
D. E. PRATT and B. J. F. HUDSON
6. Biological Effects of Food Antioxidants 193
P.BERMOND
7. Toxicological Aspects of Antioxidants Used as Food Additives . 253
S. M. BARLOW
Index 309
ix
LIST OF CONTRIBUTORS
SUSAN M. BARLOW
Toxicology and Environmental Health Division, Department of Health,
Hannibal House, Elephant and Castle, London SEl 6TE, UK
P.BERMOND
Binningerstrasse 12, 4123-Allschwil, Switzerland
M. H. GORDON
Department of Food Science and Technology, University of Reading,
Whiteknights, Reading RG6 2AP, UK
BERTRAM J. F. HUDSON
Department of Food Science and Technology, University of Reading,
Whiteknights, Reading RG6 2AP, UK
KIYOMI KIKUGAWA
Tokyo College of Pharmacy, 1432-1 Horinouchi, Hachioji, Tokyo 192-03,
Japan
S.P.KOCHHAR
Oils and Fats Section, Leatherhead Food Research Association, Leatherhead,
Surrey KT22 lRY, UK. Present address: SPK Consultancy Services, 48
Chiltern Crescent, Early, Reading, Berkshire RG6 lAN, UK
AKIRA KUNUGI
Tokyo College of Pharmacy, 1432-1 Horinouchi, Hachioji, Tokyo 192-03,
Japan
TSUTAO KUREcm
Tokyo College of Pharmacy, 1432-1 Horinouchi, Hachioji, Tokyo 192-03,
Japan
xi