The Chemistry and Technology of Edible Oils and Fats and their High Fat Products PDF
Preview The Chemistry and Technology of Edible Oils and Fats and their High Fat Products
FOOD SCIENCE AND TECHNOLOGY A SERIES OF MONOGRAPHS Editor Emeritus Bernard S. Schweigert University of California, Davis Series Editor Steve L. Taylor University of Nebraska, Lincoln Food Science and Nutrition Editorial Advisory Board Douglas Archer John E. Kinsella Center for Food & Applied Nutrition Cornell University, Ithaca FDA, Washington Daryl B. Lund Jesse F. Gregory, III State University of New Jersey, University of Florida, Gainsville New Brunswick Susan K. Harlander Barbara 0. Schneeman University of Minnesota, St Paul University of California, Davis A complete list of the books in this series is available from the publishers on request The Chemistry and Technology of Edible Oils and Fats and their High Fat Products G. Hoffmann Meeuwenlaan 26 3055 CM Rotterdam The Netherlands ACADEMIC PRESS Harcourt Brace Jovanovich, Publishers London San Diego New York Berkeley Boston Sydney Tokyo Toronto ACADEMIC PRESS LIMITED 24-28 Oval Road LONDON NW1 7DX United States Edition published by ACADEMIC PRESS INC. San Diego, CA 92101 Copyright © 1989, by ACADEMIC PRESS LIMITED All Rights Reserved No part of this book may be reproduced in any form by photostat, microfilm, or any other means, without written permission from the publishers British Library Cataloguing in Publication Data Hoffmann, G. The chemistry and technology of edible oils and fats and their high fat products 1. Fats & Oils I. Title 664\3 ISBN 0-12-352055-X Typeset by Bath Typesetting Ltd, Bath Printed in Great Britain by St Edmundsbury Press Ltd, Bury St Edmunds, Suffolk Foreword The chemistry and technology of edible oils and fats, as well as the products which contain these ingredients, constitutes an area in which many books deal both with the general and specific aspects of this subject. Consequently it requires courage and creativity to be able to add to the existing range of publications in the field. Géza Hoffmann, who can draw on more than thirty years of experience involving the many facets of the chemistry and tech nology of edible oils and fats during his work as a research chemist in Unilever Research, has filled the gap in the range of publications. He has produced a concise review which enables the reader to familiarize himself quickly and thoroughly with the subject while at the same time providing up- to-date information to the processors of edible oils and fats in a readily accessible form. I feel confident that this work will meet a long-felt need. C. Okkerse, R & D-Director Edible Fats, Unilever Research Laboratorium Viaardingen, Vlaardingen, The Netherlands v Introduction The use of animal and vegetable fats and oils for edible purposes has as long a history as mankind itself. Their use in cooking in the everyday life of ancient cultures, like the Chinese, Egyptian and Greco-Roman, was just as important as it is in ours, notwithstanding their much lower production and per capita use. The oldest known fats are those found in pots in the tombs of pharaohs. Some written reports in 1400 B.C. described the use of, probably, animal fats when "moving large stones on wooden logs", the biggest engineering achievement of ancient Egypt. Residues of soap have been found in a soap boiler, which was used to produce soap from potash and fats, in the ruins of Pompei. Ancient night lights used animal fat with a sort of cane or reed as the wick. The Romans knew candles made from tallow, the better sorts containing a mixture of tallow and beeswax. Regarding the use of oils, olives of the Mediterranean, rape seed of Europe, sesame seed of India and soya beans of China are amongst the oldest oil plants described by the ancients. The sources of fats and oils were then, as they are now, plants and animals, the latter being primarily land animals, the use of marine animals being secondary. Mainly under the pressure of an ever growing world population, new fatty raw material resources have been discovered. Agri cultural techniques have also been improved by chemical, biochemical and mechanical technological research and development, all this leading to high yielding, climate and disease resistant crop varieties. In times of serious shortage (e.g. wars, crises) both the fatty acids and glycerol, the main building blocks, could be synthesized if not for edible then at least for technical purposes. The biological synthesis of fats by means of micro organisms is completely feasible, although this is not done because of the relatively low pressure on the part of the fat/oil industry. As regards the required technology, the Chinese knew the use of wedges, whereas Plinius the Elder described the use of double-edged running grind ing stones rotating in a stone pan for crushing olives. The heating of crushed masses of seeds before pounding the mass, e.g. by stones in sacks, was a well known part of early technology. The use of animal, wind and water energy instead of human labour when grinding and stamping or pounding the mass IX X INTRODUCTION were medieval developments. The microbiological way of "rotting" the oil- bearing seeds was also well known, although only practised for technical purposes, e.g. for linseeds. However, the real breakthrough came in the preindustrial age with the application of roller-type grinders, introduced by Smeaton in 1752. The introduction of hydraulic presses for other purposes by the discovery of Brahma (1795) and Neubauer (1800) led to the appli cation of plate presses by Montgolfier (1819). The dehulling and air aspiration of cotton seed was introduced by Waring (1826), whereas the power requirements of hydraulic pressing were reduced by the accumulators developed by Armstrong (1843). The first patents for solvent extraction were issued to Deiss (1855) and Seyferth (1858), proposing carbon disulphide as solvent. Irvine, Richardson and Lundy (1864) issued a patent for the use of hydrocarbon solvents, the basis of the present-day technology. Marticke (1877) proposed the use of screw presses, although the first true expeller was introduced by Anderson in 1906. Mege Mouries obtained the first patent on the production of margarines in 1869, thus providing the fundamental basis for a breakthrough in feeding in the industrializing Western world with a cheap butter-like high-calory spread. The invention of catalytic fat-harden ing by Normann in 1902 gave the industry independence from hard animal fats, like lard and tallow, which thus made possible the use of cheap marine oils, such as fish and whale oils. It is a sad fact that this development has led to a near extinction of certain whale populations, but at least today the whales killed serve primarily as a protein source and are used mainly in the petfood and delicatessen industries and not in the edible fat industries. Among other things the continuous-chain and basket-type extractors invented by Bollmann in the 1920s gave a huge impetus to the development of a primarily animal-feed (protein) directed soya-bean industry, using many different types of extractors in order to produce enormous daily amounts of defatted meal and the "side product", the oil. Having thus reviewed briefly the main steps in the technological develop ment of the industry, it is fair to recall some major points of the scientific development, which have made it possible to reveal the fine structure of oils and fats. In 1741, Geoffroy observed that soap acidified by mineral acids is decomposed to a substance that is soluble in alcohol, this in contrast to the original raw material, the fats. Scheele, in 1779, when saponifying fats with lead oxide, produced a water miscible product, which he called "sweet oil". Today we call this product glycerol. Chevreul, over the years 1813-1825, identified the acid character of the substances we know as fatty acids, and established the alcohol character of glycerol and the role of water in saponifying fats. Because of this work, Chevreul is considered the founder of modern fat chemistry. Berthelot established the triglycéride (triacylglycerol) character of fats and hydrolysed and esterified them, respectively, in closed INTRODUCTION XI vessels under pressure. The findings of Berthelot over the years 1853—54 were the basis for the use of fatty acids for many technical purposes. The introduction of many useful group characteristics, known as "values", are connected with some personal names, e.g. the "acid-value" with Merz (1879), the "saponification value" with Koettstorfer (1879), and the first iodine value with Huebl (1879). The modern elucidation of the triglycéride composition was begun by Hilditch and his school in the 1930s by means of fractional crystallization. The introduction of chromatography, executed originally on columns by Tswett (1906) and developed in the gas phase by James and Martin (1952), for the separation of fatty acids and derivatives opened a previously unknown chapter in establishing the chemical compo sition of fats and oils and other (fatty) substances. Chromatography, in combination with different methods of instrumental physical analysis and the application of computers here and on the side of production, processing and design has completely changed the picture of the edible fat industry in the last 20 years. One might wonder why, after the publication of many excellent books on the chemistry and technology of oils and fats, some of them quite recently, another book on the same subject was felt necessary for such a relatively limited field of intellectual and practical interest. Some of these books cover broadly all the theoretical and practical aspects associated with the chemistry and technology of oils and fats, and all the fields where they can be used, not only for edible, but also for technical purposes. Others are written in languages less mastered by a broad public than English. This book gives, as an introduction, a concise treatment of fat chemistry. Thereafter the most relevant fat-separation technologies for the production of the import ant types of crude fats and oils from seeds, fruits and animal tissues are described. The oil and fat resources are not enumerated, and the use of defatted meals as animal feed and oil-seed proteins for human consumption are not elaborated further. Following this the refining and the most import ant fat-modification technologies are discussed, as these lead to those edible oils and fats which are applied in different products of high fat content, e.g. margarines (except dairy products), shortenings, mayonnaise, etc., and the speciality fats. This book is thus written on the one hand for the high-fat food manufac turer, who is often in control of only the finishing stage and not the raw- material production and processing stages. If the manufacturer is able to exert some influence on the selection and production of the raw or partly processed raw materials (intermediate/half products) used, he might do that on knowledge secured from books and other publications. On the other hand, this book might also be of interest to the oil miller or the refiner/ hardener/fat fractionator, who wants some insight into the needs of the Xll INTRODUCTION high-fat product manufacturer by taking a look at his specific products and methods. This aim will be achieved by disclosing many quality aspects of the half and final products to be controlled, besides some quality criteria of the important raw/intermediate materials involved in the processing. The basics of the most important quality-control methods, as standar dized by the International Union of Pure and Applied Chemistry (IUPAC), by the American Oil Chemists' Society (AOCS), by the German Society of Fat Science (Deutsche Gesellschaft fuer Fettwissenschaft, DGF), by some of those of the International Association of Seed Crushers (IASC) and by the British Standards Institution (BSI) were highlighted previously by the present author in Quality Control in the Food Industry (edited by S. M. Herschdoerfer, Vol. 2, 2nd edn., London: Academic Press, 1986), which can thus be used as a reference. This book is dedicated to my wife Edith, whose solidarity, understanding and patience supported and encouraged me, as always. Xlll Acknowledgements The author wishes to express his sincere gratitude to all those friends and colleagues within the Unilever organization and also outside it, who have reviewed individual chapters in their own area of specialization, including those who have helped him in the improvement of the draft manuscript as regards his English. Their advice and comments have been invaluable. The permission to use the library, internal documentation, some illustration material and the word-processing facilities of the Unilever Research Labora tory, Vlaardingen, The Netherlands, the institution in which he served with pleasure for 33 years, are most gratefully acknowledged. In spite of this long service contact, all the views given by the author remain solely his own responsibility and are not necessarily those of Unilever. Thanks are due to all those publishers, copyright owners, patented process inventors or equipment manufacturers whose published material has been used to complete this work. The description or mention of any process or firm under the illustrations or in the text does not imply any recommen dation whatsoever of the author, the items serving only as illustrations for the subjects handled. When describing the technology and processes it seemed to be of little value to collate all the items discussed with immediate literature references. All those publications (books, monographies, journals, etc.) which are considered to be relevant to the subjects discussed and which can be used as sources for further information on the matter, are fully cited in the general and the chapter-wise special literature references at the end of the book. As an exception, authors whose work contains information more specific to certain subjects, are individually cited by name and year of publication (in parentheses) in the text and are fully cited in the special reference list. xv
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