Handbook of Fat Replacers

Library of Congress Cataloging-in-Publication Data Handbook of fat replacers / edited by Sibel Roller, Sylvia A. Jones. p. cm. Includes bibliographical references (p. – ) and index. ISBN 0–8493–2512–9 (alk. paper) 1. Fat substitutes. I. Roller, Sibel. II. Jones, Sylvia A. TP447.F37H36 1996 664′ .3--dc20

95-48346 CIP

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Preface The nutritional need for fat reduction in the Western diet has been recognized for over a decade. However, a thorough understanding of the technical complexities involved in fat reduction in foods has lagged behind. This has constrained work in product development and, in many cases, has led to the development of less than optimal products. Meanwhile, in response to the needs of the food industry, an extensive number of ingredients has been developed solely for the purpose of fat replacement, using a variety of approaches and base materials. In addition, some of the well-established texturemodifying food ingredients have been found to be effective in fat replacement. Thus, over 200 ingredients are now commercially available, or are at different stages of development, that can be used to replace fat in foods. The sheer number of ingredients can be seen as a measure of the difficulties experienced in matching the multifunctional characteristics exhibited by fat in foods, and presents product development teams with a rather onerous task. Meanwhile, the issue of fat reduction remains a priority area from the perspective of both the consumer and the food industry. The purpose of this handbook is to provide, in a single volume, as much information as is practicable on the science and application of fat replacers in food products, including the multiplicity of technological, legislative, sensory, and marketing issues involved in fat replacement. Due care has been given to provide an international perspective and a multidisciplinary approach. The book is intended not only for food scientists and food technologists who wish to formulate new, low-fat food products based on an understanding of the ingredients available, but also for all food industry professionals, including ingredient manufacturers/developers who seek information on latest developments in the industry. Academic researchers and students of food science should also find the book of interest. In short, we hope the book will help fill an important gap in the food science and technology area. Part I of the book, containing five chapters, is an overview of fundamental issues important in the development of low-fat foods and ingredients used to replace fat. This section includes a historical perspective on developments in fat replacers and a critical assessment of available technological strategies, as well as chapters on nutritional implications, marketing considerations, the inter-relationships between physical and chemical aspects of fat replacement and sensory quality, and legislative implications. In Part II, commercially available fat replacers are reviewed individually and in detail. In a book of this size, it is impossible to cover all the commercial fat replacers available today. We have, therefore, selected a limited number of fat replacers each of which is representative of a group of compounds. The chapters are arranged principally according

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to chemical structure, namely, carbohydrate-based, protein-based, and lipid-based. Since a large proportion of the commercial fat replacers have been derived from carbohydrate materials, there are several chapters within this group to represent the different categories — i.e., starches, various fibers, gums and bulking agents. There is also a chapter on combination systems. Combination systems comprise blends of ingredients, the functionality of which develops in situ upon processing, and may be of an interactive or non-interactive nature. Only combination systems based on interactive blends are considered here since systems of a non-interactive nature are merely a sum of the functionalities of the different ingredients used in the blend (possibly with some synergistic effects). Furthermore, synthetic fat substitutes, which have been developed but not so far permitted for use in foods, are discussed. Among the issues covered in each chapter are: history and use of the fat replacer; production process; chemical structure and functional properties; interactions with other food ingredients; nutritional, toxicological, and legal status; and selected examples of food product formulations. The Appendix contains a comprehensive list of fat replacers classified according to their basic compositional parameters, with details on chemical composition, names of manufacturers, applications, etc. This list should allow the reader to look up a fat replacer by trade name, determine its principal composition, and then turn to a chapter in the handbook which describes in detail the fat replacer or one belonging to the same class. For example, a reader wishing to find out more about a fat replacer called Paselli SA2, when referring to the Appendix, will find it among the starch-derived group of fat replacers, and described as being a potato maltodextrin. The reader could then turn to Chapters 6A and 6B for more detailed information on maltodextrins and their role as fat mimetics. It should be noted that the inclusion of a fat replacer in this list does not indicate endorsement of the product nor does absence from the list have any negative implications. Finally, a word of explanation is required regarding terminology. Throughout this book, we have used the term “fat replacer” collectively to cover all fat mimetics and fat substitutes. In this context, the term “fat mimetic” is used to denote those ingredients which modify the aqueous phase of a food, and hence simulate some of the physical properties exhibited by fat. By contrast, the term “fat substitute” is used to denote synthetic ingredients which are purposely designed to replace fat on a weight-by-weight basis (mostly with a chemical structure resembling that of a triglyceride) but with an inherent low digestibility, which makes these ingredients non- or low-caloric, and at the same time stable at high processing temperatures (e.g., in frying). Since fat substitutes so far are not permitted for use in foods*, and this book is intended to be a practical sourcebook, fat mimetics are given most prominence. Last but not least, we would like to thank the authors of the individual chapters for their contributions, without whom a book of this nature could not have been written. Their time and effort spent on the preparation of the chapters, and their endeavors to accommodate our editorial requests, are much appreciated.** Sibel Roller Sylvia A. Jones

* Since completing this manuscript, the U.S. FDA announced on January 24, 1996 their approval for the use of olestra in selected savory snacks. ** Views and opinions expressed by the authors of the various chapters are their own and do not necessarily reflect those of the editors.

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The Editors Sibel Roller, M.Sc., Ph.D., is Professor of Food Biotechnology at South Bank University in London, U.K. Professor Roller obtained her B.A. degree in Biology in 1976 from Hunter College in New York and her M.Sc. degree in Environmental Health Sciences in 1978 from the School of Hygiene and Public Health of the Johns Hopkins University in Baltimore. She then moved to England to obtain her Ph.D. degree in 1981 in Food Microbiology from Queen Elizabeth College (now King’s College) of the University of London. While remaining at the same university, Professor Roller worked for 3 years as a Postdoctoral Research Associate on microbial fuel cells as alternative sources of energy. In 1985, she joined the Leatherhead Food Research Association in Surrey, U.K., where she initiated, developed, and led the research group in the Biotechnology Unit. As Head of the Unit, she was responsible for directing numerous short- and long-term research projects sponsored by the U.K. Ministry of Agriculture, Fisheries and Food, the Department of Trade and Industry, the European Commission, and a range of national and multinational food companies. In 1994, she was appointed to a Professorship in Food Biotechnology at South Bank University. Professor Roller is a Fellow of the Institute of Food Science and Technology (U.K.) and is an active member of the Institute’s Technical and Legislative Committee. She is a member of Sigma Xi, the Honorary Scientific Research Society, and is a Professional Member of the Institute of Food Technologists (U.S.). She is also a member of the Society of Applied Bacteriology and the Society of General Microbiology. Professor Roller currently serves on the Editorial Board of Food Biotechnology and has served on the Public Awareness Working Party of the Bioindustry Association in the U.K. Professor Roller has published over 40 refereed papers and patents and is a frequent invited speaker at international conferences. Her main research interests are in the application of biotechnology to food processing with special emphasis on developing new and upgrading old food ingredients using enzymes and microorganisms. The enzymic modification of food polysaccharides to prepare novel fat replacers, gelling agents, and thickeners is an important focus of her research work. Sylvia A. Jones, M.Sc., Ph.D., is Head of the Food Product Research and Development Department at the Leatherhead Food Research Association, U.K. Dr. Jones obtained her B.Sc. and M.Sc. degrees in Food Chemistry/Food Technology, including specialization in Human Nutrition, at the Agricultural University of Warsaw. She was awarded her Ph.D. degree at Cranfield University, U.K., following research on extrusion cooking technology.

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From 1975 to 1981, Dr. Jones was Lecturer in Food Science and Industrial Food Technology at the Agricultural University of Warsaw, during which time she also acted as a consultant for several food companies in Poland. In 1981–1982, she was Research Fellow in the Department of Food and Nutritional Sciences at Queen Elizabeth College (now King’s College), University of London, where she did research on the rheology of emulsion systems. In addition, between 1979 and 1983, she acted as technical consultant for a number of international food ingredient companies. She joined the Leatherhead Food Research Association as Principal Scientist in 1983, and progressed through Section Manager to Head of Department. Currently, she leads a multidisciplinary team of 26 scientists involved in research and development studies in a wide range of food product areas and novel processing methods. Her department comprises five sections, namely, Food Technology, Product Research and Development, Sensory Analysis and Texture Studies, Nutrition, and Microscopy. Furthermore, during the last 12 years, she has been Research Manager for both the Confectionery Products Panel and the Fruit and Vegetable Products Panel, thus responsible for undertaking research on behalf of some 400 member companies worldwide, and has directed a number of innovative research projects sponsored by the U.K. Ministry of Agriculture, Food and Fisheries, and by the European Union. In addition, over the years, Dr. Jones has developed and considerably expanded research and development consultancy activities at the Leatherhead Food Research Association; at present, a major part of her work is in the form of confidential and proprietary research undertaken for individual member companies. Dr. Jones is a Fellow of the Institute of Food Science and Technology (U.K.), and a Professional Member of the Institute of Food Technology (U.S.). She has been a member of technical committees of several food industry associations, including the U.K. Biscuit, Cake, Chocolate and Confectionery Alliance, the Food and Drink Federation, and the Microwave Working Group led by the U.K. Ministry of Agriculture, Food, and Fisheries. Her achievements in the field of food research were recognized early in her career when she received twice, in 1976 and 1979, respectively, the Rector’s Award at the Agricultural University of Warsaw, and, in 1978, she was presented with the Minister of Science, Higher Education and Technology Award. The main research interests of Dr. Jones have continued to be in the fields of food emulsions, fat reduction, food texture, food rheology, and overall structure/function relationships in foods. She has published and presented over 70 papers and patents, and has been an invited speaker to numerous international meetings throughout Europe, in the Middle East and in the United States. Her first paper on fat reduction in foods was published in 1977. Since then, she has maintained her interest in technological approaches to fat reduction, and, for the last 7 years, her major preoccupation in research and confidential work at the Leatherhead Food Research Association has been concerned with fat replacement and fat replacers.

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Contributors David A. Bell Dow Food Stabilizers The Dow Chemical Company Midland, Michigan

Debra L. Miller Biobehavioral Health and Nutrition The Pennsylvania State University University Park, Pennsylvania

Stuart M. Clegg Food Product Research and Development Department Leatherhead Food Research Association Leatherhead, Surrey, United Kingdom

Helen L. Mitchell Consultant Food Technologist Kent, United Kingdom

Eric Flack Grindsted Division Danisco Ingredients (U.K.) Ltd. Suffolk, United Kingdom Jaap Harkema Business Unit Ingredients for Food and Pharmacy AVEBE Ter Apelkanaal, The Netherlands William M. Humphreys Food Ingredients Division FMC Europe NV Brussels, Belgium Sylvia A. Jones Food Product Research and Development Department Leatherhead Food Research Association Leatherhead, Surrey, United Kingdom Pablo de Mariscal Research and Development Dow Europe, S.A. Horgen, Switzerland ©1996 CRC Press LLC

Guy Muyldermans R & D Laboratory Tessenderlo Chemie n.v. Tessenderlo, Belgium Beinta Unni Nielsen Copenhagen Pectin A/S Hercules Inc. Lille Skensved, Denmark Sibel Roller Food Research Centre South Bank University London, United Kingdom Barbara J. Rolls Laboratory for the Study of Human Ingestive Behavior The Pennsylvania State University University Park, Pennsylvania Norman S. Singer Ideas Workshop, Inc. Highland Park, Illinois Jane Smith Legislation Department Leatherhead Food Research Association Leatherhead, Surrey, United Kingdom

Barry G. Swanson Department of Food Science and Human Nutrition Washington State University Pullman, Washington

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John N. Young Market Intelligence Section Leatherhead Food Research Association Leatherhead, Surrey, United Kingdom

Contents PART I: FUNDAMENTAL ISSUES Chapter 1 Issues in Fat Replacement Sylvia A. Jones Chapter 2 Implications of Fat Reduction in the Diet Debra L. Miller and Barbara J. Rolls Chapter 3 Market Considerations in Fat Replacement John N. Young Chapter 4 Physical, Chemical, and Sensory Aspects of Fat Replacement Sylvia A. Jones Chapter 5 Legislative Implications of Fat Replacement Jane Smith PART II: FAT REPLACERS AND THEIR PROPERTIES Chapter 6A Starch-Derived Fat Mimetics: Maltodextrins Sibel Roller Chapter 6B Starch-Derived Fat Mimetics from Potato Jaap Harkema Chapter 7A Fiber-Based Fat Mimetics: Microcrystalline Cellulose William M. Humphreys

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Chapter 7B Fiber-Based Fat Mimetics: Methylcellulose Gums Pablo de Mariscal and David A. Bell Chapter 7C Fiber-Based Fat Mimetics: Pectin Beinta Unni Nielsen Chapter 8 Microparticulated Proteins as Fat Mimetics Norman S. Singer Chapter 9 The Use of Hydrocolloid Gums as Fat Mimetics Stuart M. Clegg Chapter 10 The Role of Emulsifiers in Low-Fat Food Products Eric Flack Chapter 11 The Role of the Bulking Agent Polydextrose in Fat Replacement Helen L. Mitchell Chapter 12 The Use of Blends as Fat Mimetics: Gelatin/Hydrocolloid Combinations Guy Muyldermans Chapter 13 Low-Calorie Fats and Synthetic Fat Substitutes Barry G. Swanson Appendix Classified List of Fat Replacers and Their Applications Sylvia A. Jones

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Part

I

Fundamental Issues

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Chapter

Issues in Fat Replacement Sylvia A. Jones CONTENTS 1.1 Introduction 1.2 Nutritional Background 1.3 The Functions of Fat in Food 1.3.1 Nutritional Functions of Fat 1.3.2 Physical and Chemical Functions of Fat 1.3.3 Sensory Functions of Fat 1.3.4 Overall Implications for Fat Replacement 1.4 Terminology and Classification of Fat Replacers 1.4.1 Terminology 1.4.2 Classification 1.5 Fat Replacement Strategies 1.5.1 Direct Fat Removal — No Compensation 1.5.2 Formulation Optimization 1.5.3 Technological Approach 1.5.4 Holistic Approach 1.6 Developments in Fat Replacers 1.6.1 Olestra and Its Impact 1.6.2 Maltodextrins and other Starch-Derived Fat Mimetics 1.6.3 Microparticulates 1.6.4 Fat Replacers in the Context of Functional Foods 1.6.5 Recognition of the Role of Established Food Ingredients 1.6.6 Development of Combination Systems 1.6.7 Replacing Standard Fats with Low-Calorie Fats 1.6.8 Improving the Quality of Fat Replacers 1.7 Important Considerations in the Development of Low-Fat Foods 1.7.1 Product Quality/Consumer Preference/Marketing Drive

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1

1.7.2 1.7.3 1.7.4 1.7.5 References

Knowledge of Ingredients Microbiological Implications Legislative Considerations Pricing and Marketing

1.1 INTRODUCTION With over a decade of fat replacement activities in the commercial world behind us, it is appropriate to take a comprehensive view of the principal issues involved, and examine the mechanisms and the directions of the progress made, in order to gain a better understanding of the developments and draw conclusions for the future from the learned experience. As a point of departure, it is useful to address first the principal question: is fat reduction a passing fad? To address this question, we need to look at the nutritional background to this issue, and, in particular, to assess the recent developments in nutrition science. After all, it is the consumption of fat in relation to the etiology of cardiovascular disease that triggered the sudden interest in food products with less fat (or even zero fat), both within the food industry and among the public at large. The challenge has been to produce low-fat variants with physical and sensory characteristics that resemble as closely as possible the full-fat standard products to which people were accustomed. The food industry during the last 10 to 15 years has invested considerable resources and effort into the task. One problem has been that, often, product development has been carried out without a full awareness of the different consequences of removing substantial quantities of fat from a particular product. In order to combat that, and hence develop successfully lowfat variants, it is essential to understand the multiplicity of functions of fat in foods, and, in this context, to examine the particular food matrix in which the fat is to be replaced. Because of the crucial role played by fat in foods, it quickly became obvious that the development of low-fat variants with matching quality of the full-fat counterparts depended on replacing the fat with alternative ingredients. Hence, many ingredients have been developed for the specific purpose of fat replacement. Others are food ingredients that have been used for other purposes before researchers realized that they had a role to play in fat replacement. The result is that over 200 ingredients now exist (either commercially available or at different stages of development) which can be used in fat replacement. The sheer number of ingredients is quite outstanding, but it well illustrates the difficulties encountered in matching the functionality of fat. Indeed, fat can be seen as a “gold standard” similar to sucrose in the case of sweeteners. However, sucrose replacement can now be seen as a relatively easy task compared with fat replacement. With the increase in the number of ingredients available, new terms have been introduced, causing some confusion. Thus, steps need to be taken toward a more systematic approach to both terminology and classification of the ingredients developed for the purpose of fat replacement. Another issue needing consideration is what are the different strategies that can be adopted in product development and how these have evolved and why. A holistic approach to fat replacement needs to be considered, and will be exemplified in Chapter 4 where physical, chemical, and sensory aspects of fat replacement are discussed. Meanwhile, the development of fat replacers has gone through a number of different stages. It is appropriate now to put these developments into a historical perspective and provide a logical framework by identifying the constraints and particular problems of fat replacement,

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and the driving forces behind the developments. This will therefore set the scene for the detailed discussion on the different fat replacers or categories of fat replacers given in Chapters 6 to 13. Last, but not least, when developing low-fat foods, a number of important considerations need to be taken into account. These need to encompass technological, microbiological, and legislative implications, together with marketing aspects, while keeping a watchful eye on changing consumer preferences.

1.2 NUTRITIONAL BACKGROUND Up to the 1970s, the issue of fat in the diet and its effect on health was hardly considered, except in cases of obesity where an overall reduction in energy was recommended. Reduced-calorie foods, therefore, were mainly a small niche market directed toward a minority of consumers who were obese or otherwise wished to lose body weight, and thus were interested in reducing their calorie intake. Moreover, the nutritional advice for weight loss at that time tended to focus more on carbohydrates than on fat, despite the fact that fat is the most dense source of calories (9 kcal/g vs. 4 kcal/g for carbohydrates and proteins). By the 1980s, a radical change had taken place in consumers’ attitudes. This can be traced directly to developments in the science of nutrition, and to a better understanding of the relationships between diet and health, which, in the developed countries, led to significant changes in official nutritional recommendations. In the U.K., this reevaluation was brought to public attention by the publication of two major reports which were, respectively, the so-called “NACNE Report,” produced in 1983 by the National Advisory Committee on Nutrition Education (NACNE, 1983), and Diet and Cardiovascular Disease, known as the “COMA Report,” produced in 1984 by the Committee on Medical Aspects of Food Policy (COMA) (Department of Health and Social Security, 1984). The recommendations of the NACNE Report were oriented toward a diet that would benefit the nation’s health generally, whereas those of the COMA Report were intended more specifically to prevent coronary heart disease (CHD). The major recommendation of both reports was to reduce the intake of fat from the 42% at the time to 34% (NACNE) or 35% (COMA) of total food energy in the diet. Furthermore, they recommended that the intake of saturated fat should be reduced to 10% (NACNE) or 15% (COMA) of food energy. They also advised a reduction in salt intake and increased consumption of complex carbohydrates and dietary fiber. The recommendations were widely debated and given extensive publicity in the media. The reports, therefore, had a significant impact on increasing consumer awareness of the relationship between diet and health. Similar developments took place in the United States. In 1988, the U.S. Surgeon General published a major review on nutrition and health. It proposed that energy in the diet derived from fat should be reduced to 30% (USDHHS, 1988). A further review carried out on behalf of the Food and Nutrition Board of the National Academy of Sciences (NAS, 1989) provided a broad scientific consensus for the U.S. government report: Nutrition and Your Health: Dietary Guidelines for Americans (USDA/USDHHS, 1990). The recommendations of the Surgeon General were supported by a number of health-related organizations such as the American Heart Association and the American Cancer Society, on the basis that the incidence of coronary heart disease and cancer would be reduced by decreasing the amount of fat and cholesterol in the diet (Przybyla, 1990). By the end of the 1980s, the governments of most developed countries in the western hemisphere had drawn up nutritional recommendations advising consumers to reduce fat intake from the prevailing level of 40 to 49% (depending on the country) to

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approximately 30% of total energy in the diet. In most cases, the goal was set to reduce fat consumption to the recommended level by the year 2000. In 1992, the U.K. government issued a set of targets to reduce the incidence of coronary heart disease (CHD) in the White Paper The Health of the Nation: A Strategy for Health in England (Department of Health, 1992). One target was to reduce the number of premature deaths (in people under 65 years old) by 40% by the year 2000 (using 1990 figures as a baseline). Dietary targets were set on the basis of the recommendations given in a second report by the Committee on Medical Aspects of Food Policy on dietary reference values (Department of Health, 1991), which, in the case of fat, was that it should not exceed 35% of total food energy in the diet (the same as in the COMA Report of 1984), with the consumption of saturated fatty acids no more than 11% of total food energy (4% lower than in the COMA 1984 Report). At the time, the average fat intake of the British population was at 40% of total food energy and 17% of food energy was derived from saturated fats. It would appear, therefore, that relatively little progress has been made in achieving the targets suggested by NACNE and COMA in the mid-1980s, despite the concurrent increase in sales of low-fat foods (see Chapter 3). Dietary fat in the American diet is considered to account for 36% of energy content (Buss, 1993), indicating that greater progress in adopting dietary recommendations has been made on average compared with the U.K. However, the analysis of a nutritional survey among British adults (Ministry of Agriculture, Fisheries and Food, 1994a) found that 10% of the adult population had less than 35% of their food energy derived from fat, thus indicating a significant segmentation in consumers’ response to nutritional guidelines. The extent to which consumers might be compensating for low-fat intakes when consuming low-fat products remains to be established (see Chapter 2). If that is so, a further point of interest would be to find out the extent to which the process was a physiological, as opposed to a psychological, response. Meanwhile, scientific research oriented toward understanding better the relationship between diet and health was a major growth area. One noteworthy study was that carried out by Watts et al. (1992), which was the first to support the hypothesis that a low-fat diet can actually prevent narrowing of the coronary arteries. More recently, the complex relationship between diet and heart disease has been reviewed by Ashwell (1993). While it is acknowledged that CHD is a multifactorial disorder, it is considered that diet is one component which can be modified by everybody. The report concludes that the development of CHD can be viewed simplistically as a three-stage process starting from an initial arterial injury that is followed by atherosclerosis and the formation of a blood clot which eventually blocks the artery thus causing a heart attack. Each stage can be influenced by several physiological conditions (e.g., high blood pressure, high levels of plasma lipids, and low levels of antioxidants), and these can be affected by controllable factors, including diet. A “round table model” was derived to elucidate the relationships between the stages of the disease, physiological conditions, and dietary components. The level and composition of the fats consumed is shown to be of importance at all three stages, and overall the dietary advice given includes reduction of fat intake through the consumption of low-fat products and increased intake of fish oils. There is a general consensus that the type of fat consumed is of importance in relation to the aetiology of chronic diseases. In particular, increasing the proportion of polyunsaturated fats in the diet, e.g., through the consumption of oil-rich fish, appears to play a protective role against CHD, as evident from the fact that Eskimos subsisting on a high fat diet based on fish are less prone to heart disease and thrombosis than people on high

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fat diets based more on saturated fats (Dyerberg et al., 1978; Dyerberg and Bang, 1979). The crucial factor, it seems, is the effect of consumption of different fats on the proportion of serum cholesterol associated with high-density lipoproteins (HDL cholesterol) vs. that associated with low-density lipoproteins (LDL cholesterol). Thus, consumption of fats favoring a higher proportion of HDL cholesterol and/or a lower proportion of LDL cholesterol, such as diets in which a higher proportion of fats consumed are polyunsaturated (e.g., from fish or certain vegetable sources) or monounsaturated (e.g., from olive oil), tend to reduce risk from CHD (helped also by the consumption of dietary antioxidants such as Vitamin E, which blocks the oxidative modification of LDL). Conversely, a higher proportion of saturated fats in the diet tends to increase the ratio of LDL cholesterol to HDL cholesterol, thus increasing risk of CHD (Grundy, 1994). However, it is now evident that different saturated fats and dietary sources of saturated fat vary in their influence on the level of LDL cholesterol (Richardson, 1995). For instance, butter and other dairy products, which are high in myristic acid (14:0), appear to strongly increase levels of LDL cholesterol, whereas beef fat, containing palmitic (16:0) and stearic (18:0) acids does so to a lesser extent, and cocoa butter, with a high proportion of stearic acid, increases LDL cholesterol only slightly. In addition, there has been increasing concern and controversy on the consumption of trans fatty acids in relation to health (Mensink and Katan, 1990; Grundy, 1994). Epidemiological data (Willett et al., 1993) have shown a positive association between higher intakes of trans isomers (derived from partially hydrogenated vegetable oils) and the risk of CHD. Wahle and James (1993) have published a comprehensive review on this topic, and concluded that some evidence exists to suggest that trans fatty acids have deleterious effects on blood plasma lipids (i.e., they tend to increase the levels both of LDL and HDL cholesterol present, as well as the concentration of lipoprotein a (which is a genetic marker for CHD acting as an independent risk factor). However, other studies have given conflicting results, so that the issue at present remains unresolved, with a majority of studies implicating trans fatty acids. Clearly, more research is required on this issue. Meanwhile, the FAO/WHO Expert Committee concluded that the effects on plasma cholesterol concentrations exerted by trans unsaturated fatty acids are similar to saturated fatty acids and hence they have recommended that in order to improve plasma lipid profile, the intake of trans fatty acids should be cut back when the intake of saturated fats is reduced (Sanders, 1995). In short, while our knowledge of the relationship between diet and health continues to progress, the adoption of dietary recommendations derived from that knowledge consistently lags behind. It is possible that a better consumer response could be achieved primarily by more extensive nutritional education and secondly, by improving the quality of existing or new low-fat foods. On the other hand, it is likely that as the market matures, with increasing availability of low-fat foods to a wider range of social strata, consumers might more readily adhere to the guidelines regarding fat consumption.

1.3 THE FUNCTIONS OF FAT IN FOOD The level of fat determines the nutritional, physical, chemical, and sensory characteristics of foods. Before the replacement of fat in food products can be considered, however, it is essential to understand what its various functions are. 1.3.1 NUTRITIONAL FUNCTIONS OF FAT Physiologically, fats in foods have three basic functions: they act as a source of essential fatty acids (linolenic and linoleic acids); they act as carriers for fat-soluble vitamins

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(A, D, E and K); and they are an important source of energy. From a nutritional point of view, only the first two may be considered as essential because other nutrients (namely carbohydrates and proteins) can act as sources of energy. Normally, even diets very low in fat can satisfy those requirements. The overriding issue today is that changes in people’s lifestyles over the years have meant that the requirements for energy from food have decreased significantly. At the same time, the proportion of energy derived from fat (the consumption of which, as noted already, apart from being the most concentrated source of energy, has other adverse effects on health) has remained high. Figure 1.1 illustrates the relative contribution of fat from different foods in an intake of 88 g/day which is the average for the U.K., and represents 38% of total energy or approximately 40% of energy from food, i.e., excluding alcohol (Ministry of Agriculture, Fisheries and Food, 1994a).

Figure 1.1 Sources of fat in diet of U.K. consumers. (Compiled from Ministry of Agriculture, Fisheries and Food, 1994a).

The nutritional function of fat in food would not be complete without mentioning its physiological/psychological aspect, mainly the extent to which fat plays a role in achieving satiety. Research has shown that the consumption of fat is associated with a subsequent state of “fulfillment,” such that, by implication, fat reduction might lead to energy compensation and the increased consumption of food. This issue is discussed in detail in Chapter 2. However, it should be pointed out that most studies on satiety have been carried out using noncaloric, nonabsorbable fat substitutes (such as sucrose polyesters). As will be discussed, so far such fat substitutes have not been approved for use in foods, and therefore the studies do not address the current market reality where fat mimetics are used to reduce the fat content of food products. A study on satiety involving three different types of fat mimetics is currently being undertaken at the Leatherhead Food Research Association, supported by the U.K. Ministry of Agriculture, Fisheries and Food.

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1.3.2 PHYSICAL AND CHEMICAL FUNCTIONS OF FAT Physical and chemical functions of fat in food products can be grouped together since the chemical nature of fats determines more or less their physical properties. Thus, the length of the carbon chain of fatty acids esterified with the glycerol, their degree of unsaturation, and the distribution of fatty acids and their molecular configuration (i.e., whether in the form of cis or trans isomers), as well as the polymorphic state of the fat, will all affect the physical properties of foods (for example, viscosity, melting characteristics, crystallinity, and spreadability). Furthermore, fat affects the physical and chemical properties of the product, and hence has several practical implications, the most important of which are (1) the behavior of the food product during processing (e.g., heat stability, viscosity, crystallization, and aerating properties), (2) post-processing characteristics (e.g., shear-sensitivity, tackiness, migration, and dispersion), and (3) storage stability, which can include physical stability (e.g., de-emulsification, fat migration, or fat separation), chemical stability (e.g., rancidity or oxidation), and microbiological stability (e.g., water activity and safety). 1.3.3 SENSORY FUNCTIONS OF FAT Last, but not least, fats have an important function in determining the four main sensory characteristics of food products, which are (1) appearance (e.g., gloss, translucency, color, surface uniformity, and crystallinity) (2) texture (e.g., viscosity, elasticity, and hardness), (3) flavor (namely, intensity of flavor, flavor release, flavor profile, and flavor development), and (4) mouthfeel (e.g., meltability, creaminess, lubricity, thickness, and degree of mouth-coating). Sensory and related aspects of fat reduction are discussed in detail in Chapter 4. 1.3.4 OVERALL IMPLICATIONS FOR FAT REPLACEMENT Reducing fat in a food product must take into account its multifunctional role, in particular how its location in the food matrix determines the chemical, physical, and sensory properties of the food, as well as its processing characteristics. The relative importance of the different functions of the fat in a food vary according to the particular food product and according to the type of fat used. The greater number of product quality characteristics determined by the fat, the more pronounced will be its effect, and the more complex will be the approach required when a substantial part of the fat is to be replaced. In the development of low-fat products, it has been found useful to visualize the overall functionality profile of a product making use of a “fishbone” diagram. This approach was used, for instance, by Loders Crocklaan for designing speciality fats for particular product applications (Anon., 1994). Figure 1.2 illustrates the basic technique whereby a full functionality profile for a given product can be translated into a detailed set of physical/chemical and sensory attributes. By the same token, a detailed functionality profile resulting from the presence of fat in a product can be defined and used as a tool in product development for finding ingredient systems that will deliver the required profile. “Fishbone” diagrams have also been used to illustrate the multifunctional aspects of fat reduction (Anon., 1992).

1.4 TERMINOLOGY AND CLASSIFICATION OF FAT REPLACERS 1.4.1 TERMINOLOGY Over the years, different terms have been used for ingredients that have been specifically developed to replace fat in food products. This has created some confusion over the

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Figure 1.2 Basic fishbone diagram for product development and reformulation purposes. (From Source, Issue No. 13, January, 6, 1994. Reprinted with the permission of Loders Croklaan.)

terminology used for fat-replacing ingredients in the literature. Thus, there is a need to introduce a more systematic approach to this issue. Initially, the term “fat substitute” was used for all such ingredients regardless of the extent to which they were able to replace fat and principles determining their functionality. However, the main interest then had been directed toward discovering an optimal ingredient able to replace fat fully in all food systems. Such an ideal ingredient would need to have a similar chemical structure and similar physical properties to fat, but would need to be resistant to hydrolysis by digestive enzymes in order to have preferably a zero or very low caloric value. In the second half of the 1980s, the only ingredients able to fulfill all those requirements were synthetic compounds such as olestra. The main practical difference between these synthetic compounds and other ingredients launched for the purposes of fat replacement was that only the former were able, by definition, to replace fat on a weight-by-weight basis. All other ingredients, on the other hand, required water to achieve their functionality, and their ability to replace fat was based on the principle of reproducing (mimicking) some of the physical and sensory characteristics associated with the presence of fat in the food. Hence, the term “fat mimetic” evolved to distinguish this group of ingredients. With separate terms now being used to define these different types of ingredients, there was the need for an overall term that referred to all ingredients used for fat–replacement purposes, and the general term “fat replacer” began to be used in that context. However, many authors continue to use the term “fat substitute” for all fat replacing ingredients, and an even greater number use the terms “fat substitute,” “fat mimetic,” and “fat replacer” more or less interchangeably, thus causing confusion on the meanings of these terms. In addition, as a result of further developments, other terms have been introduced by ingredient manufacturers. For instance, the term “fat extender” has been used by Pfizer to describe a system comprising a mixture of ingredients, containing standard fats or oils, such as Veri-Lo® 100 and Veri-Lo® 200, which are emulsions containing 33 and 25% fat, respectively. On the other hand, ingredients such as Caprenin and Salatrim,

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which are true fats (i.e., they are triglycerides) but with a fatty acid composition different from standard fats designed to provide fewer calories (see below), may also be described as “fat extenders.” However, when Salatrim was launched, the term “low-calorie fat” was promoted, and has since evolved as a term in its own right, distinct from “fat extenders.” Thus, Caprenin and Salatrim are now more usually placed in an independent group under the heading “low-calorie fats.” Hence, the term “fat extender” now tends to be reserved for systems combining standard fats or oils with other ingredients, as in the case of Veri-Lo®. In summary, the five terms used to describe ingredients which can replace fat may be defined briefly as follows: Fat replacer: a blanket term to describe any ingredient used to replace fat Fat substitute: a synthetic compound designed to replace fat on a weight-by-weight basis, usually having a similar chemical structure to fat but resistant to hydrolysis by digestive enzymes Fat mimetic: a fat replacer that requires a high water content to achieve its functionality Low-calorie fat: synthetic triglyceride combining unconventional fatty acids to the glycerol backbone which results in reduced caloric value Fat extender: a fat replacement system containing a proportion of standard fats or oils combined with other ingredients

It should be added that the current lack of development activity for the last category of fat replacers might lead to the disappearance of the term in due course; however, it is included in the above list for completeness. 1.4.2 CLASSIFICATION One of the main characteristics of the ingredients used to replace fat is that they lack similarity both in terms of chemical structure and in a specific physical structure. All they have in common is that under certain conditions, they are able to replace fat and fulfill at least some of the functional properties associated with fat in a given product. By definition, therefore, they represent a disparate group of ingredients for which it is not easy to provide a simple classification. An additional problem is that the group as a whole is quite unbalanced in which some subgroups of ingredients of similar chemical structure and functional properties comprise a large number while others may contain only one or two ingredients developed so far. In short, a systematic approach (i.e., based on a single feature or characteristic) cannot be used because too many ingredients would be excluded. Furthermore, there is the issue as to whether to include in any classification all ingredients currently used, or have potential use as fat replacers, or whether it should consist only of those ingredients that have been purposely designed to act as fat replacers. The classification of fat replacers given below aims to give the reader a comprehensive view of ingredient categories that can be considered for product development of low-fat foods (including the synthetic fat substitutes, none of which, as yet, are permitted for use in foods)*. The list is based partially on chemical composition and partially on functionality of the ingredients, and includes combination systems (i.e., blends). 1. Starch-derived 2. Fiber-based * Since completing this manuscript, the U.S. FDA announced on January 24, 1996 their approval for the use of olestra in selected savory snacks.

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3. 4. 5. 6. 7. 8. 9. 10.

Protein-based Gums, gels and thickeners Emulsifiers Bulking agents Low-calorie fats Fat extenders Synthetic fat substitutes Combination systems

As may be seen, a certain degree of overlap cannot be avoided. For instance, it can be debated whether low-calorie fats should be considered as a separate entity, or be included in the synthetic fat substitute category. However, since the low-calorie fats structurally are lipids, and were assigned a separate term from other fat replacers when launched on the market, it is considered more appropriate to differentiate them from the category of the, as yet, unpermitted fat substitutes in the above classification.

1.5 FAT REPLACEMENT STRATEGIES A number of approaches have evolved in the development of reduced-fat foods. In this section, the main options will be discussed briefly in the order that they were introduced. 1.5.1 DIRECT FAT REMOVAL — NO COMPENSATION During the rush of publicity of the new nutritional recommendations in the early 1980s, the first strategy to evolve was simply to remove fat from the standard product, without any attempt to address the organoleptic changes resulting from the reduced presence of the fat. The dairy industry was the first to adopt such a strategy, with the introduction of semi-skimmed, and subsequently, skimmed milk. Fat content was reduced from the 3.5% in the standard product, to, respectively, 1.7% (i.e., a 50% fat reduction) and 0.1% (i.e., a more or less 100% reduction), in effect, replacing the fat with a proportional increase of all the other constituents of milk. This somewhat drastic strategy, which changed considerably the organoleptic quality of the final product, had many skeptics who doubted whether consumers would accept such a change. It was thought that after the initial “hype” period, consumers would gradually go back to the standard “full-fat” milk, and demand for the reduced-fat varieties would dwindle to a small niche market. However, history proved otherwise. In the U.K., for example, as indicated in Figure 1.3, the consumption of reduced-fat liquid milk grew at a remarkable rate. According to the most recent National Food Survey in Britain, the consumption of reduced-fat milk has now overtaken that of whole milk (Ministry of Agriculture, Fisheries and Food, 1994b). In other words, the strategy of direct fat removal adopted by the dairy industry proved a major success, gaining widespread consumer acceptance in spite of the obvious changes in product characteristics. Similar developments subsequently took place in the meat industry. Thus, lean and extra lean raw beef, pork and lamb (mostly in a minced or diced form, chilled or frozen) are now readily available in the supermarkets of many of the developed countries, with a fat content ranging from 15 to 10%, and even as low as 5%. Such a strategy is less possible for most other food products because, for the majority, physical stability, functional properties, and, in many cases, microbiological stability, are adversely affected. The same applies when fat is replaced by water alone. Direct fat removal without compensation, therefore, has limited applicability, depending on the type of product, and the level of fat reduction intended. Since this strategy expects the consumer to accept considerable change in the organoleptic characteristics of a product,

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Figure 1.3 Consumption of liquid milk (g/d) in the U.K. (Compiled from Ministry of Agriculture, Food and Fisheries, National Food Surveys for 1984–1993.)

it can only work well when the consumer is highly motivated, and where, therefore, fat content and nutritional concerns in general will influence purchasing behavior. In short, the limited number of products to which this strategy can be applied has meant that other ways of achieving fat reduction have had to be sought. 1.5.2 FORMULATION OPTIMIZATION The major challenge in the development of reduced-fat foods is to achieve fat reduction while matching as closely as possible the eating qualities of the traditional full-fat product. This involves the creative use of established functional ingredients, including the range of fat replacers now available. For most food products, reduction of fat is associated with an increase in water content. The first need, therefore, in order to mimic the quality of the full-fat product, is to attempt to structure the water phase, through the use of such functional ingredients as proteins, starches and other thickeners, gums, stabilizers, gelling agents, bulking agents, emulsifiers and fibers. The choice of ingredients will depend on product type and the level of fat reduction intended, and needs to be carefully balanced against their effects on the multiplicity of product characteristics. The strategy requires a thorough knowledge of the ingredients available, and an understanding of the structure/function relationships in a given product matrix. During the second half of the 1980s, when the emphasis was narrowly focused on the search for an optimal new fat replacer, developments in other directions were somewhat limited. However, once the inherent limitations of the various fat replacers introduced to the market were realized, interest in the creative use of the standard functional ingredients increased considerably. The introduction of new ingredients designed specifically to replace fat (i.e., fat replacers) significantly increased the scope for matching the quality of reduced-fat variants. Currently, as noted already, there are over 200 ingredients with some claim for

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aiding fat replacement, either available commercially, or at an advanced stage of development (see Section 1.6). Most of the fat replacers on the market are based on the ability to structure the water phase toward achieving fat-like structures that mimic the physical and/or perceived sensory characteristics of fat. 1.5.3 TECHNOLOGICAL APPROACH The use of specially designed fat replacers in products often requires changes in processing conditions or additional processing stages in order to achieve optimal functionality. However, the technological approach can be extended much further in fat replacement strategies. One example would be to explore interactive processing. This is based on the principle of employing a processing method purposely designed to cause interactions between ingredients, and changes in ingredient functionalities within the food matrix, in such a way that they compensate for the removal of fat in the final product. On the other hand, the application of a new technology, or an existing technology that is not normally used in the production of the standard product, can be sought. To date, neither of these approaches has been explored to any great extent. 1.5.4 HOLISTIC APPROACH The holistic approach to fat reduction is based on the fact that, on the one hand, the vast majority of food products are relatively complex systems, and, on the other hand, any one fat mimetic has limitations in its ability to cover the many different functions of fat. The strategy has evolved because in most cases it has been found that no single approach to fat replacement gives a satisfactory final product with significant fat reduction, without compromising some of the quality characteristics (e.g., sensory, physical stability, microbiological stability) of the standard product. It has normally taken the form of using a chosen fat replacer in conjunction with other ingredients (e.g., stabilizers, emulsifiers), or the use of a blend of ingredients designed for a particular product application. More recently, this has shifted toward using more than one fat replacer in conjunction with a range of standard ingredients. However, the ultimate holistic strategy, with the goal of producing optimal quality products with low-fat levels or in fat-free versions, needs to go beyond the issue of ingredients used, toward encompassing all technological means for achieving the required fat reduction. Indeed, this does not only apply to the development of low-fat products, but to all food product development. In a holistic strategy even greater attention must be directed toward achieving an understanding of the functionality of the various ingredients, and how they interact with one another. Many of the advances in product development activities have been predominantly empirically based. In general, low-fat products, because they are deprived of the functionality of fat, are much more sensitive to molecular interactions, especially those between flavor and other ingredients, and those which affect texture. Thus, when developing low-fat products, much more attention needs to be given to all aspects of the often complex and finely balanced physical and chemical system as a whole. This emphasizes the need for a holistic strategy.

1.6 DEVELOPMENTS IN FAT REPLACERS Although the fat replacement issue has been on the agenda for more than a decade, it was not until the late 1980s and early 1990s that the development of ingredients specifically for fat replacement really took off. The fact that there are so many ingredients now available for use in fat replacement means that this has been one of the strongest growth areas in the field of ingredient development for some time. In this section, the various developments in fat replacers are put in a historical context, highlighting the ©1996 CRC Press LLC

main events, in order to show how each development had an impact on further research activities. It sets the scene for the more detailed discussion on the different fat replacers or categories of fat replacers in Chapters 6 through 13. 1.6.1 OLESTRA AND ITS IMPACT Initially, as previously mentioned, the desire was to find an ingredient that would behave, both physically and chemically, like fat, while contributing fewer calories, and which could be used in all product types by directly substituting for the fat, with little or no need to reformulate the product. Olestra, a sucrose polyester, first synthesized in 1968 and patented by the Procter & Gamble Company in 1971, precisely fitted those criteria (Mattson and Volpenheim, 1971). With sucrose substituting for the glycerol moiety in triglycerides, and six to eight of the hydroxyl groups of the sucrose esterified by fatty acids, the chemical structure of olestra is rather similar to fat. The main difference is that the molecule cannot be hydrolyzed by pancreatic lipases, and hence passes straight through the gastrointestinal tract unchanged without being absorbed. It thus contributes no calories. Furthermore, its physical properties could be manipulated by varying the chain length, the degree of unsaturation and the proportions of different fatty acids used to esterify the hydroxyl groups of the sucrose molecule. Finally, because it is inherently heat stable, it can substitute for fat over a wide range of applications in the food industry (including in frying oils), and in virtually every type of food product. It was not until the late 1970s and early 1980s, when the nutritional arguments for reducing fat consumption were being publicized, that a viable market for olestra started to become apparent. Its current status is that it is still awaiting official approval for use in food. Procter & Gamble submitted its first petition for approval to the U.S. Food and Drug Administration (FDA) in April 1987. A further petition was submitted in July 1990, restricting its use to savory snacks (Anon., 1991a). The company has also filed for the approval of olestra in Canada and in the U.K. (Anon., 1990). It was hoped that approval would be obtained in 1995, especially since a second 1-year interim extension to the Procter & Gamble’s patent awarded by the U.S. Patent and Trademark Office is due to expire in January 1996 (Anon., 1995). Under the current U.S. legislation concerning products which require lengthy regulatory review, if olestra were to be approved before this date, then it would be possible for Procter & Gamble’s patent to be extended for an additional 2 years from the time of its approval by the FDA. There is also the issue that even if approved, it is not certain whether olestra will gain consumer acceptance. However, it is noteworthy that, despite, on the one hand, its synthetic nature, and, on the other hand, a concurrent consumer trend in the 1980s toward “natural” and “additivefree” products, olestra has continued to receive remarkably positive publicity. For completeness, it should be added that a number of other synthetic fat substitutes have been developed. These include esterified propoxylated glycerols, carboxy-carboxylate esters, malonate esters, alkyl glyceryl-ethers, alkyl glycoside fatty acid polyesters, esterified polysaccharides, polyvinyl oleate, ethyl esters, polysiloxanes, and many more (Bowes, 1993). These are discussed in Chapter 13. It is interesting to note, though, that none of the companies developing these synthetic fat substitutes have so far attempted to go through the hurdles of gaining approval from the U.S. Food and Drug Administration, but rather have resigned themselves to waiting for the outcome of the application for olestra. However, it should be pointed out that a joint agreement was signed in 1990 between the companies Arco and CPC International to develop esterified propoxylated glycerol, and subsequently to prepare the necessary scientific data required if the ingredient is to gain approval (Anon., 1991a). Meanwhile, the nonavailability of olestra in the 1980s had the effect of stimulating developments in fat replacers in other directions. ©1996 CRC Press LLC

1.6.2 MALTODEXTRINS AND OTHER STARCH-DERIVED FAT MIMETICS In the early days of fat replacement, relatively small reductions in fat were considered an acceptable goal, perhaps by a quarter or a third compared with the fat content of the standard product. In many cases, this could be achieved with the use of different types of starch-derived fat mimetics, which, in contrast to olestra, do not have any regulatory hurdles to pass over. One of the first starch-derived mimetics to enter the market was N-Oil, a tapioca dextrin, which had been produced by National Starch & Chemical Corporation since 1984 (Dziezak, 1989). The most significant amount of research activity on starch-derived mimetics has centered around the development of maltodextrins — i.e., starch hydrolysis products obtained by acid or enzymic hydrolysis of starch materials and characterized by a low dextrose equivalent (DE) value. The concept of starch hydrolysis products with DE