Handbook of fat replacers

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

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No claim to original U.S Government works International Standard Book Number 0-8493-2512-9 Library of Congress Card Number 95-48346 Printed in the United States of America 1 2 3 4 5 6 7 8 9 0 Printed on acid-free paper

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 infat reduction in foods has lagged behind This has constrained work in product develop-ment 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 ofingredients 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 modifying 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 devel-opment, that can be used to replace fat in foods The sheer number of ingredients can

texture-be seen as a measure of the difficulties experienced in matching the multifunctionalcharacteristics 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 fromthe 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, includingthe multiplicity of technological, legislative, sensory, and marketing issues involved infat replacement Due care has been given to provide an international perspective and amultidisciplinary approach The book is intended not only for food scientists and foodtechnologists who wish to formulate new, low-fat food products based on an understand-ing of the ingredients available, but also for all food industry professionals, includingingredient manufacturers/developers who seek information on latest developments in theindustry 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 scienceand technology area

Part I of the book, containing five chapters, is an overview of fundamental issuesimportant in the development of low-fat foods and ingredients used to replace fat Thissection includes a historical perspective on developments in fat replacers and a criticalassessment of available technological strategies, as well as chapters on nutritional impli-cations, marketing considerations, the inter-relationships between physical and chemicalaspects 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 availabletoday We have, therefore, selected a limited number of fat replacers each of which isrepresentative of a group of compounds The chapters are arranged principally according

to chemical structure, namely, carbohydrate-based, protein-based, and lipid-based Since

a large proportion of the commercial fat replacers have been derived from carbohydratematerials, there are several chapters within this group to represent the differentcategories — i.e., starches, various fibers, gums and bulking agents There is also achapter 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 areconsidered here since systems of a non-interactive nature are merely a sum of thefunctionalities of the different ingredients used in the blend (possibly with some syner-gistic 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 chapterare: history and use of the fat replacer; production process; chemical structure andfunctional 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 totheir basic compositional parameters, with details on chemical composition, names ofmanufacturers, 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 thehandbook 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 fatreplacers, and described as being a potato maltodextrin The reader could then turn toChapters 6A and 6B for more detailed information on maltodextrins and their role as fatmimetics It should be noted that the inclusion of a fat replacer in this list does notindicate endorsement of the product nor does absence from the list have any negativeimplications

Finally, a word of explanation is required regarding terminology Throughout thisbook, we have used the term “fat replacer” collectively to cover all fat mimetics and fatsubstitutes In this context, the term “fat mimetic” is used to denote those ingredientswhich modify the aqueous phase of a food, and hence simulate some of the physicalproperties exhibited by fat By contrast, the term “fat substitute” is used to denotesynthetic ingredients which are purposely designed to replace fat on a weight-by-weightbasis (mostly with a chemical structure resembling that of a triglyceride) but with aninherent low digestibility, which makes these ingredients non- or low-caloric, and at thesame 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 practicalsourcebook, fat mimetics are given most prominence

Last but not least, we would like to thank the authors of the individual chapters fortheir 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 toaccommodate 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.

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 fromHunter 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 inBaltimore She then moved to England to obtain her Ph.D degree in 1981 in FoodMicrobiology from Queen Elizabeth College (now King’s College) of the University ofLondon 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., whereshe 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 researchprojects sponsored by the U.K Ministry of Agriculture, Fisheries and Food, the Depart-ment of Trade and Industry, the European Commission, and a range of national andmultinational food companies In 1994, she was appointed to a Professorship in FoodBiotechnology 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 ProfessionalMember 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 Rollercurrently serves on the Editorial Board of Food Biotechnology and has served on thePublic Awareness Working Party of the Bioindustry Association in the U.K

Professor Roller has published over 40 refereed papers and patents and is a frequentinvited speaker at international conferences Her main research interests are in theapplication of biotechnology to food processing with special emphasis on developingnew and upgrading old food ingredients using enzymes and microorganisms The enzy-mic 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 DevelopmentDepartment at the Leatherhead Food Research Association, U.K Dr Jones obtained herB.Sc and M.Sc degrees in Food Chemistry/Food Technology, including specialization

in Human Nutrition, at the Agricultural University of Warsaw She was awarded herPh.D degree at Cranfield University, U.K., following research on extrusion cookingtechnology

From 1975 to 1981, Dr Jones was Lecturer in Food Science and Industrial FoodTechnology 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 ResearchFellow 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 ofemulsion systems In addition, between 1979 and 1983, she acted as technical consultantfor a number of international food ingredient companies She joined the LeatherheadFood Research Association as Principal Scientist in 1983, and progressed through SectionManager to Head of Department

Currently, she leads a multidisciplinary team of 26 scientists involved in research anddevelopment studies in a wide range of food product areas and novel processing methods.Her department comprises five sections, namely, Food Technology, Product Researchand Development, Sensory Analysis and Texture Studies, Nutrition, and Microscopy.Furthermore, during the last 12 years, she has been Research Manager for both theConfectionery Products Panel and the Fruit and Vegetable Products Panel, thus respon-sible 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 theyears, Dr Jones has developed and considerably expanded research and developmentconsultancy activities at the Leatherhead Food Research Association; at present, a majorpart of her work is in the form of confidential and proprietary research undertaken forindividual member companies

Dr Jones is a Fellow of the Institute of Food Science and Technology (U.K.), and aProfessional 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 theMicrowave 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 whenshe received twice, in 1976 and 1979, respectively, the Rector’s Award at the AgriculturalUniversity 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 foodemulsions, fat reduction, food texture, food rheology, and overall structure/functionrelationships in foods She has published and presented over 70 papers and patents, andhas been an invited speaker to numerous international meetings throughout Europe, inthe Middle East and in the United States Her first paper on fat reduction in foods waspublished 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 andconfidential work at the Leatherhead Food Research Association has been concernedwith fat replacement and fat replacers

David A Bell

Dow Food Stabilizers

The Dow Chemical Company

Midland, Michigan

Stuart M Clegg

Food Product Research and

Development DepartmentLeatherhead Food Research Association

Leatherhead, Surrey, United Kingdom

Eric Flack

Grindsted Division

Danisco Ingredients (U.K.) Ltd

Suffolk, United Kingdom

Jaap Harkema

Business Unit Ingredients for Food and

PharmacyAVEBE

Ter Apelkanaal, The Netherlands

Leatherhead, Surrey, United Kingdom

Pablo de Mariscal

Research and Development

Dow Europe, S.A

Horgen, Switzerland

Debra L Miller

Biobehavioral Health and NutritionThe Pennsylvania State UniversityUniversity Park, Pennsylvania

Tessenderlo, Belgium

Beinta Unni Nielsen

Copenhagen Pectin A/SHercules Inc

Lille Skensved, Denmark

Sibel Roller

Food Research CentreSouth Bank UniversityLondon, United Kingdom

Barbara J Rolls

Laboratory for the Study of Human Ingestive BehaviorThe Pennsylvania State UniversityUniversity Park, Pennsylvania

Norman S Singer

Ideas Workshop, Inc

Highland Park, Illinois

Jane Smith

Legislation DepartmentLeatherhead Food Research AssociationLeatherhead, Surrey, United Kingdom

Leatherhead, Surrey, United Kingdom

Implications of Fat Reduction in the Diet

Debra L Miller and Barbara J Rolls

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

Part I

Fundamental

Issues

1 Chapter

Issues in Fat Replacement

Sylvia A Jones CONTENTS

1.1 Introduction1.2 Nutritional Background 1.3 The Functions of Fat in Food1.3.1 Nutritional Functions of Fat1.3.2 Physical and Chemical Functions of Fat 1.3.3 Sensory Functions of Fat

1.3.4 Overall Implications for Fat Replacement1.4 Terminology and Classification of Fat Replacers1.4.1 Terminology

1.4.2 Classification1.5 Fat Replacement Strategies 1.5.1 Direct Fat Removal — No Compensation 1.5.2 Formulation Optimization

1.5.3 Technological Approach1.5.4 Holistic Approach1.6 Developments in Fat Replacers1.6.1 Olestra and Its Impact 1.6.2 Maltodextrins and other Starch-Derived Fat Mimetics1.6.3 Microparticulates

1.6.4 Fat Replacers in the Context of Functional Foods 1.6.5 Recognition of the Role of Established Food Ingredients1.6.6 Development of Combination Systems

1.6.7 Replacing Standard Fats with Low-Calorie Fats1.6.8 Improving the Quality of Fat Replacers 1.7 Important Considerations in the Development of Low-Fat Foods1.7.1 Product Quality/Consumer Preference/Marketing Drive

1.7.2 Knowledge of Ingredients 1.7.3 Microbiological Implications1.7.4 Legislative Considerations1.7.5 Pricing and MarketingReferences

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 examinethe mechanisms and the directions of the progress made, in order to gain a betterunderstanding of the developments and draw conclusions for the future from the learnedexperience

As a point of departure, it is useful to address first the principal question: is fatreduction a passing fad? To address this question, we need to look at the nutritionalbackground to this issue, and, in particular, to assess the recent developments in nutritionscience After all, it is the consumption of fat in relation to the etiology of cardiovasculardisease that triggered the sudden interest in food products with less fat (or even zerofat), 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 asclosely as possible the full-fat standard products to which people were accustomed Thefood industry during the last 10 to 15 years has invested considerable resources andeffort 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 fatfrom a particular product In order to combat that, and hence develop successfully low-fat 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 thedevelopment of low-fat variants with matching quality of the full-fat counterpartsdepended on replacing the fat with alternative ingredients Hence, many ingredients havebeen developed for the specific purpose of fat replacement Others are food ingredientsthat 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 (eithercommercially available or at different stages of development) which can be used in fatreplacement The sheer number of ingredients is quite outstanding, but it well illustratesthe 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, sucrosereplacement 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 offat replacement

Another issue needing consideration is what are the different strategies that can beadopted 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 wherephysical, chemical, and sensory aspects of fat replacement are discussed Meanwhile,the development of fat replacers has gone through a number of different stages It isappropriate now to put these developments into a historical perspective and provide alogical framework by identifying the constraints and particular problems of fat replacement,

and the driving forces behind the developments This will therefore set the scene for thedetailed 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 consider-ations need to be taken into account These need to encompass technological, microbi-ological, and legislative implications, together with marketing aspects, while keeping awatchful 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 aminority of consumers who were obese or otherwise wished to lose body weight, andthus were interested in reducing their calorie intake Moreover, the nutritional advice forweight loss at that time tended to focus more on carbohydrates than on fat, despite thefact that fat is the most dense source of calories (9 kcal/g vs 4 kcal/g for carbohydratesand 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 betterunderstanding of the relationships between diet and health, which, in the developedcountries, led to significant changes in official nutritional recommendations

In the U.K., this reevaluation was brought to public attention by the publication oftwo 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 Healthand Social Security, 1984) The recommendations of the NACNE Report were orientedtoward a diet that would benefit the nation’s health generally, whereas those of the COMAReport were intended more specifically to prevent coronary heart disease (CHD) Themajor recommendation of both reports was to reduce the intake of fat from the 42% atthe 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 andincreased consumption of complex carbohydrates and dietary fiber The recommendationswere widely debated and given extensive publicity in the media The reports, therefore,had a significant impact on increasing consumer awareness of the relationship betweendiet and health

Similar developments took place in the United States In 1988, the U.S SurgeonGeneral published a major review on nutrition and health It proposed that energy in thediet derived from fat should be reduced to 30% (USDHHS, 1988) A further reviewcarried out on behalf of the Food and Nutrition Board of the National Academy ofSciences (NAS, 1989) provided a broad scientific consensus for the U.S governmentreport: Nutrition and Your Health: Dietary Guidelines for Americans (USDA/USDHHS,1990) The recommendations of the Surgeon General were supported by a number ofhealth-related organizations such as the American Heart Association and the AmericanCancer Society, on the basis that the incidence of coronary heart disease and cancerwould 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 thewestern hemisphere had drawn up nutritional recommendations advising consumers toreduce fat intake from the prevailing level of 40 to 49% (depending on the country) to

approximately 30% of total energy in the diet In most cases, the goal was set to reducefat consumption to the recommended level by the year 2000.

In 1992, the U.K government issued a set of targets to reduce the incidence ofcoronary 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 1990figures 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 dietaryreference values (Department of Health, 1991), which, in the case of fat, was that itshould 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 foodenergy (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 wasderived from saturated fats

It would appear, therefore, that relatively little progress has been made in achievingthe targets suggested by NACNE and COMA in the mid-1980s, despite the concurrentincrease in sales of low-fat foods (see Chapter 3) Dietary fat in the American diet isconsidered to account for 36% of energy content (Buss, 1993), indicating that greaterprogress in adopting dietary recommendations has been made on average compared withthe 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 hadless than 35% of their food energy derived from fat, thus indicating a significant seg-mentation in consumers’ response to nutritional guidelines The extent to which con-sumers might be compensating for low-fat intakes when consuming low-fat productsremains 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 apsychological, response

Meanwhile, scientific research oriented toward understanding better the relationshipbetween diet and health was a major growth area One noteworthy study was that carriedout by Watts et al (1992), which was the first to support the hypothesis that a low-fatdiet can actually prevent narrowing of the coronary arteries

More recently, the complex relationship between diet and heart disease has beenreviewed by Ashwell (1993) While it is acknowledged that CHD is a multifactorialdisorder, 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 athree-stage process starting from an initial arterial injury that is followed by atheroscle-rosis 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), andthese can be affected by controllable factors, including diet A “round table model” wasderived to elucidate the relationships between the stages of the disease, physiologicalconditions, and dietary components The level and composition of the fats consumed isshown to be of importance at all three stages, and overall the dietary advice given includesreduction 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 saturated fats in the diet, e.g., through the consumption of oil-rich fish, appears to play

polyun-a protective role polyun-agpolyun-ainst CHD, polyun-as evident from the fpolyun-act thpolyun-at Eskimos subsisting on polyun-a highfat diet based on fish are less prone to heart disease and thrombosis than people on high

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 thatassociated with low-density lipoproteins (LDL cholesterol) Thus, consumption of fatsfavoring a higher proportion of HDL cholesterol and/or a lower proportion of LDLcholesterol, such as diets in which a higher proportion of fats consumed are polyunsat-urated (e.g., from fish or certain vegetable sources) or monounsaturated (e.g., from oliveoil), tend to reduce risk from CHD (helped also by the consumption of dietary antioxi-dants 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 LDLcholesterol 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 intheir influence on the level of LDL cholesterol (Richardson, 1995) For instance, butterand other dairy products, which are high in myristic acid (14:0), appear to stronglyincrease levels of LDL cholesterol, whereas beef fat, containing palmitic (16:0) andstearic (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 betweenhigher intakes of trans isomers (derived from partially hydrogenated vegetable oils) andthe risk of CHD Wahle and James (1993) have published a comprehensive review onthis topic, and concluded that some evidence exists to suggest that trans fatty acids havedeleterious effects on blood plasma lipids (i.e., they tend to increase the levels both ofLDL 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 studieshave given conflicting results, so that the issue at present remains unresolved, with amajority of studies implicating trans fatty acids Clearly, more research is required onthis issue Meanwhile, the FAO/WHO Expert Committee concluded that the effects onplasma cholesterol concentrations exerted by trans unsaturated fatty acids are similar tosaturated fatty acids and hence they have recommended that in order to improve plasmalipid profile, the intake of trans fatty acids should be cut back when the intake of saturatedfats 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 knowledgeconsistently lags behind It is possible that a better consumer response could be achievedprimarily 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, consumersmight 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 essentialfatty acids (linolenic and linoleic acids); they act as carriers for fat-soluble vitamins

(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 (namelycarbohydrates 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 inpeople’s lifestyles over the years have meant that the requirements for energy from foodhave decreased significantly At the same time, the proportion of energy derived fromfat (the consumption of which, as noted already, apart from being the most concentratedsource 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/daywhich is the average for the U.K., and represents 38% of total energy or approximately40% of energy from food, i.e., excluding alcohol (Ministry of Agriculture, Fisheries andFood, 1994a)

The nutritional function of fat in food would not be complete without mentioning itsphysiological/psychological aspect, mainly the extent to which fat plays a role in achiev-ing satiety Research has shown that the consumption of fat is associated with a subse-quent state of “fulfillment,” such that, by implication, fat reduction might lead to energycompensation 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 beencarried 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 mimeticsare used to reduce the fat content of food products A study on satiety involving threedifferent types of fat mimetics is currently being undertaken at the Leatherhead FoodResearch Association, supported by the U.K Ministry of Agriculture, Fisheries and Food

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

1.3.2 PHYSICAL AND CHEMICAL FUNCTIONS OF FAT

Physical and chemical functions of fat in food products can be grouped together sincethe chemical nature of fats determines more or less their physical properties Thus, thelength of the carbon chain of fatty acids esterified with the glycerol, their degree ofunsaturation, 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 charac-teristics, crystallinity, and spreadability)

Furthermore, fat affects the physical and chemical properties of the product, and hencehas several practical implications, the most important of which are (1) the behavior ofthe food product during processing (e.g., heat stability, viscosity, crystallization, andaerating 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 sensorycharacteristics 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 develop-ment), 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, inparticular how its location in the food matrix determines the chemical, physical, andsensory properties of the food, as well as its processing characteristics The relativeimportance of the different functions of the fat in a food vary according to the particularfood product and according to the type of fat used The greater number of product qualitycharacteristics determined by the fat, the more pronounced will be its effect, and themore complex will be the approach required when a substantial part of the fat is to bereplaced

In the development of low-fat products, it has been found useful to visualize theoverall functionality profile of a product making use of a “fishbone” diagram Thisapproach was used, for instance, by Loders Crocklaan for designing speciality fats forparticular product applications (Anon., 1994) Figure 1.2 illustrates the basic techniquewhereby a full functionality profile for a given product can be translated into a detailedset of physical/chemical and sensory attributes By the same token, a detailed function-ality 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 requiredprofile “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 specificallydeveloped to replace fat in food products This has created some confusion over the

terminology used for fat-replacing ingredients in the literature Thus, there is a need tointroduce 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 toreplace fat and principles determining their functionality However, the main interest thenhad been directed toward discovering an optimal ingredient able to replace fat fully inall food systems Such an ideal ingredient would need to have a similar chemical structureand similar physical properties to fat, but would need to be resistant to hydrolysis bydigestive enzymes in order to have preferably a zero or very low caloric value In thesecond half of the 1980s, the only ingredients able to fulfill all those requirements weresynthetic compounds such as olestra The main practical difference between these syn-thetic compounds and other ingredients launched for the purposes of fat replacementwas that only the former were able, by definition, to replace fat on a weight-by-weightbasis All other ingredients, on the other hand, required water to achieve their function-ality, 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 inthe 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 forfat–replacement purposes, and the general term “fat replacer” began to be used in thatcontext However, many authors continue to use the term “fat substitute” for all fatreplacing ingredients, and an even greater number use the terms “fat substitute,” “fatmimetic,” and “fat replacer” more or less interchangeably, thus causing confusion on themeanings of these terms.

In addition, as a result of further developments, other terms have been introduced byingredient manufacturers For instance, the term “fat extender” has been used by Pfizer

to describe a system comprising a mixture of ingredients, containing standard fats oroils, such as Veri-Lo® 100 and Veri-Lo® 200, which are emulsions containing 33 and25% fat, respectively On the other hand, ingredients such as Caprenin and Salatrim,

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.)

which are true fats (i.e., they are triglycerides) but with a fatty acid composition differentfrom 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 “fatextenders.” Thus, Caprenin and Salatrim are now more usually placed in an independentgroup 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 thecase 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-weightbasis, usually having a similar chemical structure to fat but resistant to hydrolysis

1.4.2 CLASSIFICATION

One of the main characteristics of the ingredients used to replace fat is that they lacksimilarity both in terms of chemical structure and in a specific physical structure Allthey have in common is that under certain conditions, they are able to replace fat andfulfill 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 isnot easy to provide a simple classification An additional problem is that the group as awhole is quite unbalanced in which some subgroups of ingredients of similar chemicalstructure and functional properties comprise a large number while others may containonly 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 classificationall ingredients currently used, or have potential use as fat replacers, or whether it shouldconsist 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 comprehensiveview of ingredient categories that can be considered for product development of low-fatfoods (including the synthetic fat substitutes, none of which, as yet, are permitted foruse in foods)* The list is based partially on chemical composition and partially onfunctionality 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.

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 beincluded in the synthetic fat substitute category However, since the low-calorie fatsstructurally are lipids, and were assigned a separate term from other fat replacers whenlaunched on the market, it is considered more appropriate to differentiate them from thecategory 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 thissection, 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, withoutany attempt to address the organoleptic changes resulting from the reduced presence ofthe 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 the3.5% 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 proportionalincrease of all the other constituents of milk This somewhat drastic strategy, whichchanged considerably the organoleptic quality of the final product, had many skepticswho doubted whether consumers would accept such a change It was thought that afterthe 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 themost recent National Food Survey in Britain, the consumption of reduced-fat milk hasnow 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 andextra 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, areadversely affected The same applies when fat is replaced by water alone Direct fatremoval without compensation, therefore, has limited applicability, depending on thetype of product, and the level of fat reduction intended Since this strategy expects theconsumer to accept considerable change in the organoleptic characteristics of a product,

it can only work well when the consumer is highly motivated, and where, therefore, fatcontent 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 otherways 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 reductionwhile matching as closely as possible the eating qualities of the traditional full-fatproduct This involves the creative use of established functional ingredients, includingthe 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, emulsi-fiers and fibers The choice of ingredients will depend on product type and the level offat reduction intended, and needs to be carefully balanced against their effects on themultiplicity of product characteristics The strategy requires a thorough knowledge ofthe 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 wasnarrowly focused on the search for an optimal new fat replacer, developments in otherdirections were somewhat limited However, once the inherent limitations of the variousfat replacers introduced to the market were realized, interest in the creative use of thestandard functional ingredients increased considerably

The introduction of new ingredients designed specifically to replace fat (i.e., fatreplacers) significantly increased the scope for matching the quality of reduced-fatvariants Currently, as noted already, there are over 200 ingredients with some claim for

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.)

aiding fat replacement, either available commercially, or at an advanced stage of opment (see Section 1.6) Most of the fat replacers on the market are based on the ability

devel-to structure the water phase devel-toward achieving fat-like structures that mimic the physicaland/or perceived sensory characteristics of fat

1.5.3 TECHNOLOGICAL APPROACH

The use of specially designed fat replacers in products often requires changes in cessing conditions or additional processing stages in order to achieve optimal function-ality However, the technological approach can be extended much further in fat replace-ment strategies One example would be to explore interactive processing This is based

pro-on the principle of employing a processing method purposely designed to cause actions between ingredients, and changes in ingredient functionalities within the foodmatrix, in such a way that they compensate for the removal of fat in the final product

inter-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 vastmajority of food products are relatively complex systems, and, on the other hand, anyone 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, withoutcompromising some of the quality characteristics (e.g., sensory, physical stability, micro-biological stability) of the standard product It has normally taken the form of using achosen 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 Morerecently, this has shifted toward using more than one fat replacer in conjunction with arange of standard ingredients However, the ultimate holistic strategy, with the goal ofproducing 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 meansfor achieving the required fat reduction Indeed, this does not only apply to the devel-opment of low-fat products, but to all food product development In a holistic strategyeven greater attention must be directed toward achieving an understanding of the func-tionality of the various ingredients, and how they interact with one another Many of theadvances in product development activities have been predominantly empirically based

In general, low-fat products, because they are deprived of the functionality of fat, aremuch more sensitive to molecular interactions, especially those between flavor and otheringredients, 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 finelybalanced physical and chemical system as a whole This emphasizes the need for aholistic strategy

1.6 DEVELOPMENTS IN FAT REPLACERS

Although the fat replacement issue has been on the agenda for more than a decade, itwas not until the late 1980s and early 1990s that the development of ingredients specif-ically for fat replacement really took off The fact that there are so many ingredientsnow available for use in fat replacement means that this has been one of the strongestgrowth areas in the field of ingredient development for some time In this section, thevarious developments in fat replacers are put in a historical context, highlighting the

main events, in order to show how each development had an impact on further researchactivities 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 whichcould be used in all product types by directly substituting for the fat, with little or noneed to reformulate the product Olestra, a sucrose polyester, first synthesized in 1968and patented by the Procter & Gamble Company in 1971, precisely fitted those criteria(Mattson and Volpenheim, 1971) With sucrose substituting for the glycerol moiety intriglycerides, and six to eight of the hydroxyl groups of the sucrose esterified by fattyacids, the chemical structure of olestra is rather similar to fat The main difference isthat the molecule cannot be hydrolyzed by pancreatic lipases, and hence passes straightthrough the gastrointestinal tract unchanged without being absorbed It thus contributes

no calories Furthermore, its physical properties could be manipulated by varying thechain 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 inherentlyheat 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 forreducing 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 andDrug 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 theapproval of olestra in Canada and in the U.K (Anon., 1990) It was hoped that approvalwould be obtained in 1995, especially since a second 1-year interim extension to theProcter & Gamble’s patent awarded by the U.S Patent and Trademark Office is due toexpire in January 1996 (Anon., 1995) Under the current U.S legislation concerningproducts which require lengthy regulatory review, if olestra were to be approved beforethis date, then it would be possible for Procter & Gamble’s patent to be extended for anadditional 2 years from the time of its approval by the FDA There is also the issue thateven if approved, it is not certain whether olestra will gain consumer acceptance How-ever, it is noteworthy that, despite, on the one hand, its synthetic nature, and, on theother hand, a concurrent consumer trend in the 1980s toward “natural” and “additive-free” products, olestra has continued to receive remarkably positive publicity

For completeness, it should be added that a number of other synthetic fat substituteshave been developed These include esterified propoxylated glycerols, carboxy-carbox-ylate 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, thatnone 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 tration, but rather have resigned themselves to waiting for the outcome of the applicationfor olestra However, it should be pointed out that a joint agreement was signed in 1990between the companies Arco and CPC International to develop esterified propoxylatedglycerol, and subsequently to prepare the necessary scientific data required if the ingre-dient is to gain approval (Anon., 1991a)

Adminis-Meanwhile, the nonavailability of olestra in the 1980s had the effect of stimulatingdevelopments in fat replacers in other directions

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 thestandard 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 regulatoryhurdles to pass over

One of the first starch-derived mimetics to enter the market was N-Oil, a tapiocadextrin, which had been produced by National Starch & Chemical Corporation since

1984 (Dziezak, 1989) The most significant amount of research activity on starch-derivedmimetics has centered around the development of maltodextrins — i.e., starch hydrolysisproducts obtained by acid or enzymic hydrolysis of starch materials and characterized

by a low dextrose equivalent (DE) value The concept of starch hydrolysis products withDE<10 was pioneered at the Academy of Science in the former German DemocraticRepublic, where potato starch was partially degraded using a-amylase, a process thatwas subsequently patented (Richter et al., 1973) Since such maltodextrins when used

in solution at a concentration greater than 20% form thermoreversible gels, with some

of the sensory characteristics of fats, and caloric value amounts to approximately 1 kcal/g,there was scope for exploring these ingredients for the purposes of fat replacement Onthe other hand, both enzymic and acid hydrolysis methods can be applied to any type

of starch or material high in starch content, and hence, not surprisingly, a large number

of maltodextrins from different sources have been developed and are available cially A detailed discussion of these fat mimetics is given in Chapter 6A, and Chapter 6B

commer-covers the maltodextrins derived from potato starch A list of commercially availablemaltodextrins is given in the Appendix Although the main focus was concentrated onmaltodextrins, a few modified starches were also introduced to the market for fat replace-ment purposes toward the end of the 1980s and in the beginning of the 1990s (e.g., theSta-Slim™ range from the company A E Staley and the Amalean range from the Amer-ican Maize Products Company) Some further developments in starch-derived fat mimet-ics will be highlighted later

In the late 1980s, when the trend had shifted toward developing food productscontaining even lower amounts of fat, and in the midst of the “hype” associated withsynthetic fat substitutes at that time, fat mimetics, such as those derived from starch,were at a serious disadvantage because they could not fulfill all the criteria for an optimal(ideal) fat replacer Furthermore, under the influence of olestra, which had been submitted

to the FDA for approval, the whole climate of opinion then was dominated by theperceived need to find a single ingredient that had the potential of replacing fat acrossthe whole spectrum of product applications Thus, fat replacement reached something

of an impasse: a market existed for low-fat foods, but while synthetic fat substitutes werenot approved for use in food, other ingredients, such as starch-derived fat replacers, couldonly replace some of the functions of fat in foods, and, as fat mimetics, had restrictedapplications

1.6.3 MICROPARTICULATES

The first technological breakthrough (or, more precisely, what was perceived as a through at the time) came with the development of Simplesse®, a microparticulatedprotein fat mimetic introduced by the NutraSweet Company, the main version of which

break-is based on whey protein concentrate (Singer et al., 1988) — see Chapter 8 for a detaileddiscussion on Simplesse® It was launched in January 1988, receiving much publicity inthe media

It should be added that while John Labatt Ltd., Canada, the originator of the plesse® concept sold the rights to Simplesse® to the NutraSweet Company, further

Sim-developments were on-going at Ault Foods Ltd., a division of John Labbatt Ltd., whichculminated in 1989 with the launch of a whey protein concentrate-based fat mimeticunder the name Dairylight (Anon 1991b) The difference between Simplesse® andDairylight lies in the processing method employed, whereby the latter involves only amild treatment which leads only to partial denaturation of protein (60 to 80%), and hence

it is not a microparticulated protein (Asher et al., 1992) Four years later, in 1993, thecompany Pfizer relaunched Dairylight under the Dairy-Lo™ name as a result of anagreement reached between Pfizer Company and Ault Foods Ltd., whereby Ault Foodswould produce Dairy-Lo™ and Pfizer would market it in all countries with the exception

of Canada (Anon., 1993)

The concept of a microparticulated protein as a fat mimetic was seen by many as theultimate development in ingredient technology with the potential of resolving all theproblems associated with fat replacement, including that of total fat replacement Thesebeliefs were compounded by the strong marketing strategy of the NutraSweet Company.However, strong marketing was needed at the time in order to combat the general opinionthat fat mimetics were by definition underperformers as compared with the “true” fatreplacers such as olestra which, in spite of their failure to gain approval for use in foods,were still seen as the ideal fat replacers The concept of a special processing methodleading to a microparticulated form of an ingredient was seen as one that can actuallymimic the fat droplets in an oil-in-water emulsion, and hence the developments in protein-based fat replacers were oriented toward some form of microparticulates (see Chapter 4

for a more detailed discussion of this issue) While LITA® (from the company Opta FoodIngredients, Inc.) and Trailblazer (from Kraft General Foods) followed this concept usingmulticomponent systems based on proteins, a large number of insoluble fat mimeticsalso started to be marketed as having what had become the fashionable microparticulatedform (e.g., the Avicel® range from FMC, and Stellar™ a crystalline starch from A E.Staley)

Back in the late 1980s, Simplesse® was also promoted on the basis of its natural (asopposed to synthetic) character, since it was produced from a well-recognized naturalingredient (i.e., whey protein concentrate or egg white/skimmed milk/sugar/pectin forSimplesse® 100 and Simplesse® 300, respectively) The fact that these ingredients wereoriginally produced only in a liquid form, and hence had a short shelf-life and requiredrefrigeration was probably (at least initially) a contributing factor to the positive image

of these ingredients (Further developments of Simplesse® 100 are outlined in

1.6.4 FAT REPLACERS IN THE CONTEXT OF FUNCTIONAL FOODS

The link between fat replacers and functional foods has not previously been made.However, that an association does exist, as will be demonstrated here, is worth pointingout amidst the current high level of interest in functional foods

One definition for a functional food states that it is a food which positively affectsphysiological functions of the body in a targeted way as a result of it containing ingre-dients which may, in due course, justify health claims (Roberfroid, 1995) Taking thisissue broadly, it can be argued that all foods with reduced fat content can be considered

as functional foods given the nutritional benefits of fat reduction as discussed in

Section 1.1 Most of the ingredients used to replace fat, of course, do not provide anyspecial positive physiological benefits themselves However, fiber-based fat replacers canclaim such benefits since there is a growing recognition for the role of dietary fiber indisease prevention, particularly in relation to colonic cancer and heart disease (e.g., Asp

et al., 1993; Stark and Madar, 1994; Kritchesky, 1994)

Thus, a number of fat replacers have been launched based on fiber from a number ofdifferent sources, such as oats, sugar beet, soy beans, almonds, and peas For instance,Advanced Oat Fibers manufactured by the company Williamson Fiber Products in Irelandwere first introduced in 1988 Oat fiber is also a good source of b-glucan which is claimed

to have cholesterol-lowering properties (Duxbury, 1990) Oatrim fat replacer, developedand patented by the U.S Department of Agriculture is obtained through the enzymicmodification of oat starch in the oat flour or bran, and contains from 1 to 10% of b-glucan (Inglett and Grisamore, 1991) Both ConAgra and Rhône-Poulenc/Quaker OatsCompany are currently producing Oatrim under separate license agreements Anotherfiber ingredient, Fibercel, developed by Alpha-Beta Technologies, is composed of 85 to90% β-glucan obtained from a food-grade yeast product (Jamas et al., 1990) A range

of cellulose-based fat replacers should also be mentioned as a source of fiber (see

Appendix) Moreover, in the particular case of inulin fat replacers (for instance Raftiline®

from Orafti, Belgium, and Fibruline® from Cosucra SA, Belgium), positive physiologicalbenefits arise from their bifidus stimulating properties (Roberfroid, 1995)

1.6.5 RECOGNITION OF THE ROLE OF ESTABLISHED

FOOD INGREDIENTS

Gradually, the realities of the market place began to shift away from the mythical “oneingredient can solve it all” and toward a more holistic strategy Moreover, meanwhile,commercial pressures were moving the goal-posts of fat reduction to well beyond the50% mark, thus making it even more difficult to achieve fat replacement without a holisticstrategy in which ingredients such as, gums, emulsifiers, thickeners, stabilizers, andbulking agents, along with gelatin and other proteins and untreated starches could playcrucial roles Previously, this group of ingredients had been overshadowed by the orien-tation toward discovering the “optimal” fat replacer

However, the important role of these well-established ingredients is clearly evidentwhen examining low-fat or zero-fat products currently on the market (Bavington et al.,1992) While in many cases, these ingredients are used in conjunction with those devel-oped purposely for replacing fat, in some products, fat reduction has been achieved bystructuring the water phase using only gums and stabilizers (e.g., Kraft’s “Free Choice”Vinaigrette Style Fat-Free Dressing) Thus, the role of ingredients such as gums, stabi-lizers, thickeners and emulsifiers needs to be firmly emphasized in the context of fatreplacement That is why this group of ingredients has been placed in a separate category

in the classification of ingredients given earlier Details on the uses of gums, bulkingagents and emulsifiers are given in Chapters 9, 10, and 11, respectively, and cellulose-based stabilizers, and their use for fat mimicking purposes, is discussed in Chapters 7A

and 7B The scope for utilizing functional food ingredients in fat replacement was furtherhighlighted in 1991 by the commercialization of Slendid®, a proprietary pectin developed

by Hercules, Inc., and marketed by Copenhagen Pectin A/S (see Chapter 7C)

1.6.6 DEVELOPMENT OF COMBINATION SYSTEMS

The launch of the N-Lite range of fat mimetics by National Starch & Chemical ration in January 1992, as well as widening the scope for the use of starch-derivedingredients for fat replacement purposes, was of considerable significance because itestablished a new trend This was the development of combination systems (i.e., blends

Corpo-of ingredients) for use in fat replacement in specific product applications For example,N-Lite F, specifically designed for use in icings, fillings, frozen desserts and dry mixes,was a blend of modified starch, non-fat milk solids, polyglycerol ester and guar gum Ineffect, therefore, the necessity for the holistic approach to fat replacement has beenacknowledged Most notably, it was in this context that modified starch was shown tohave a useful role in fat replacement.

In fact, some blends were on the market before 1992 Indeed, a number were launched

in the second half of the 1980s, but received few headlines, because, at the time, thesearch for the single “magic” ingredient was the dominant theme Developments in theuse of blends as fat replacers have taken a number of forms, but, in the main, the approachhas been to prepare a formulation containing three or more ingredients which, eithercould be more universally applied, or, were designed for a specific product category Thelatter approach has tended to dominate (for obvious reasons), and the blends typicallyincluded as ingredients are gums, stabilizers, thickeners, and emulsifiers, together withstandard protein sources (see Appendix for a list of blended ingredient systems that are

of an interactive combination system is the Slimgel® range launched by P.B Gelatins,Belgium, at the end of 1993 It is composed of gelatin and galactomannans, and itsperformance is based on thermodynamic incompatibility between these two hydrocol-loids, which, in turn, leads to phase separation (Muyldermans, 1993, see also Chapter 12).The advantage of blends, ideally, is that they shorten the time and effort required todevelop new low-fat or fat-free products However, the disadvantage is that when sig-nificant development work is required to best match a given full-fat variant, the use of

a blend might prove too inflexible, and inhibit the ingredient optimization process, sincethe precise composition of the main functional system used is not known The concept

of using a range of ingredients in an attempt to reproduce the different functions of fat

in the full-fat product goes some way toward a holistic strategy This was particularlynecessary by early 1990s, by which time, partly due to commercial pressures and partlydue to new legislative restrictions regarding claims (see Chapter 5), the goal-posts forfat reduction had moved yet again, this time toward the ultimate limit — i.e., zero fat

1.6.7 REPLACING STANDARD FATS WITH LOW-CALORIE FATS

The concept of replacing fat with a low-calorie fat entered the scene in the early 1990s

By that time, the likelihood of obtaining FDA approval for the use of olestra within ashort time-scale was dwindling rapidly, and, on the other hand, it was recognized thatthe commercially available fat mimetics did not provide an easy answer to fat replace-ment, and, moreover, their use was restricted, in general, to water-based food systems

In this context, the idea of using the basic structure of a triglyceride molecule, butchanging the composition of the fatty acids esterified with the glycerol backbone in order

to achieve caloric reduction appeared to be very plausible Moreover, the fact thatmedium-chain triglycerides, which usually comprise caprylic (C8) and capric (C10) fattyacids, are GRAS ingredients with a 35-year track record in clinical medicine (e.g., fortreating patients suffering from lipid malabsorption symptoms or for use in infant for-mulae) was a distinct advantage (Latta, 1990; Megremis, 1991) These compoundsprovide energy (8.3 kcal/g) but are metabolized through the liver, and are characterized

by a low tendency for becoming incorporated into tissue as depot fat Currently, chain triglycerides are marketed by the U.S company Karlshamns Food Ingredients(Captex 300, 350 and 355, now known as AKomed range) and by Stepan Company(Neobee® M-5) However, as pointed out by Thayer (1992), there are certain limitations

medium-to the use of medium-chain triglycerides in foods since, upon hydrolysis, the free fattyacids released give strong off-flavors

The concept of using medium-chain triglycerides together with long-chain fatty acids(e.g., behenic acid — C22) was developed jointly by Procter & Gamble and GrinstedProducts, Inc and commercialized under the name Caprenin The incorporation ofbehenic acid (which is only partially absorbed in the gut), together with caprylic andcapric acids, gives further caloric reduction, and the net result is that Caprenin providesonly 5 kcal/g (Peters et al., 1991; Webb and Sanders, 1991) More information onCaprenin is given in Chapter 13 Caprenin has been used commercially as a substitutefor cocoa butter in the product Milky Way II produced by M & M Mars (introduced into

a test market area in the U.S in March 1992), and (in September 1992) in Hershey’sReduced Calorie and Fat Candy Bar In both cases, the Caprenin was used in conjunctionwith polydextrose to achieve a 25% reduction in caloric value compared with the standardproduct However, since then, there seems to have been no apparent progress in the use

of Caprenin as a fat replacer

The most recent addition to the low-calorie fat category is Salatrim, developed byNabisco Foods Group in conjunction with Pfizer Food Science, and launched in July

1994 Salatrim is a family of triglycerides comprising mixtures of long-chain fatty acids(predominantly stearic acid) and short-chain fatty acids (mainly acetic acid, propionicacid, and/or butyric acid) esterified with glycerol As a result of this chemical structure,the caloric value of Salatrim is 5 kcal/g (Smith et al., 1994) It is not expected that thecommercial availability of Salatrim will be hindered by the FDA approval process since

it is made from natural substances commonly used in foods and produced by an lished interesterification process (petition filed with the FDA in mid-1994) No toxiceffects were observed in animal studies of up to 13 weeks duration and in clinical studies,Salatrim was found to be well tolerated in doses of up to 30 g/d (Smith et al., 1994) Atthe time of writing, Nabisco was hoping to launch chocolate bars containing Salatrim

estab-by mid-1995, and Pfizer Food Science was planning subsequently to launch ice cream,cheeses, baked goods and table spreads made from Salatrim However, the incorporation

of Salatrim into frying oils has not been suggested (see Chapter 13) The future willshow whether low-calorie fats will be seen as a commercially viable option for the foodindustry

1.6.8 IMPROVING THE QUALITY OF FAT REPLACERS

Developments of fat replacers have not only been confined to the development of newingredients In addition, much effort has been made by ingredient manufacturers toimprove further the quality of the existing fat replacers in terms of their functionality,ease of use and heat stability, with the aim of expanding their industrial applications.Three trends can be identified: instantization; alterations in functionality profile; and ease

of use during product manufacture

Instantization is an obvious and well-established route for ingredient extension Thus,

a number of ingredient manufacturers have launched instant versions of their fat mimetic.This is evident from the list of fat replacers given in the Appendix

The second trend can be seen as a reflection of the realization that no fat mimetic,however good, can mimic all the functional characteristics provided by a fat in a givenproduct Thus, one or more other ingredients were being added to alter and improve the

functionality profile provided by the original ingredient in order to obtain some additional

“fat-like” property (e.g., development of the Novagel™ range of fat replacers by F.M.C.,based on Avicel®) The extreme form of this trend was its extension into the development

of blends, as discussed above

The need for ingredients which were easy to use during the manufacture of foodproducts was especially in evidence during the first half of the 1990s This is associatedwith the fact that the use of many of the fat replacers that have been developed neces-sitated either the preparation of a solution and/or special processing when placed insolution, prior to addition to other ingredients, e.g., the Rafticreming stage required forRaftiline®, and the high shearing (8000 psi) required for Stellar™ (Pszczola, 1991).Hence, the subsequent developments aimed to remove these additional stages in productmanufacture while providing the expected functionality, and new variants entered themarket (e.g., Raftiline® HP and Instant Stellar™)

In the overall context of improvements in the quality and flexibility of fat replacers,Simplesse® deserves special mention, since the original ingredient (Simplesse® 100)which was commercialized in a liquid form (42.5% solids) with a short shelf-life andlow heat resistance, was developed into a dry form (Simplesse® 100D) able to withstandUHT pasteurization or retorting, without loss of functionality

1.7 IMPORTANT CONSIDERATIONS IN THE DEVELOPMENT

OF LOW-FAT FOODS

A reduced-fat food product, when compared with the standard product it is replacing,more often than not has different requirements from the points of view of manufacturers,retailers, and consumers For instance, a change in the technology used in manufactureand manufacturing practice may be required, which, furthermore, might have cost impli-cations A change in pack design, e.g., with improved barrier properties, greater physicalprotection or a reduced pack size, may be called for where shelf-life is reduced In somecases, changes in temperature or timescale of distribution may be necessary

While achieving optimal product quality is obviously the primary consideration inthe pursuit of fat reduction, it is crucial to base this on an understanding of how theingredients function, and, taking into account microbiological and legislative implica-tions, appropriately designing a marketing strategy These issues are highlighted in thefollowing discussion

1.7.1 PRODUCT QUALITY/CONSUMER PREFERENCE/MARKETING DRIVE

Clearly, the organoleptic properties of the low-fat product ultimately determine thesuccess or failure of the product, since consumers are unlikely (at least in the firstinstance) to sacrifice taste and quality in order to reduce calories in their diet (see

Chapter 4 for a detailed discussion on sensory aspects of fat reduction and flavor release).However, the success of the dairy industry in applying the strategy of direct fat removal,which, as noted already, resulted in dramatic organoleptic changes, suggests that con-sumer perceptions and liking of high-fat products can be modified over time Indeed,there is already some evidence that consumer preference is shifting toward products with

a medium, as opposed to those containing a higher level of fat (Wyeth and Kilcast, 1991;Mela and Marshall, 1992) In other words, consumers’ attitudes to health and diet areapparently beginning to have a significant influence on food choice, and a greater desirefor foods with healthier nutritional characteristics is starting to influence organolepticpreferences Thus, increased consumption of some low-fat product variants can causechanges in preferences, which, in turn, changes acceptability patterns It can be argued,

therefore, that for these patterns to emerge, the quality of the products with medium fatreduction may be the key to future developments In this context, the market drive forfat-free variants may be seen as being premature for some product categories.

The positioning of a particular product in the diet should, in principle, determine thelevel of fat reduction required and the product quality that can be achieved at differentfat levels should be balanced against that before making a marketing decision This helps

to explain why some of the fat-free variants, despite apparently different characteristicsfrom the equivalent standard product, appear to be of greater appeal to consumers thanothers

1.7.2 KNOWLEDGE OF INGREDIENTS

When developing a product where fat reduction is achieved through the incorporation

of a fat replacer, it is of considerable importance to know or establish: first, the physicaland chemical characteristics of the functional ingredients used; second, what the possibleinteractions with other food components might be; and third, what the implications might

be for the processing operations, i.e., what changes in processing might need to beemployed in order to achieve maximum functionality

Thus, a full knowledge of a range of fat replacers, which can be used effectively tonarrow down the number of fat replacers suitable for a particular product type, is essential

if product development is to be carried out in an efficient manner Moreover, anyadjustments in other ingredients present in the standard full-fat formulation need to beguided by a knowledge of their functionality It is important to be especially flexible asfar as the processing method is concerned, since, in some cases, small adjustments inthe standard method might be required, whereas in others, the optimal solution might

be to consider other technological options (e.g., through technology transfer, or bydevising a new technology altogether)

1.7.3 MICROBIOLOGICAL IMPLICATIONS

A reduction in fat content in a given product formulation is usually associated with asimultaneous increase in moisture content, which thus affects microbiological stability,and hence the safety of the product must be given due consideration For example, low-fat spreads require the addition of a preservative such as potassium sorbate which is notnormally necessary for full-fat margarine, and, moreover, they have a considerably shortershelf-life Similarly, many low-fat dressings, unlike the full-fat equivalent, require refrig-eration after opening In other words, for many reduced-fat products, consumers have tochange the way in which they use the product compared with the full-fat equivalent, and

it has to be ensured that consumers are aware of that

It is well recognized that water activity, acidity, preservatives, and the extent of heattreatment are the main factors affecting product shelf-life and microbiological safety.However, it should be mentioned that although water activity measurements have beenused in the food industry for nearly 40 years as a food safety parameter, this is nowconsidered inadequate by some, who argue that greater emphasis should be placed onglass transition temperature (Slade and Levine, 1991; Franks, 1991) Franks (1991)suggests that change in water availability, especially in the case of intermediate or lowmoisture products, is related to the rate of water diffusion in the product, which, in turn,

is related to the glass-rubber transition of the material and the sensitivity of the transitiontemperature to changes in the moisture content As yet, there is no consensus on thistopic Meanwhile, therefore, water activity remains the basic method for ascertainingmicrobiological stability

In many low-fat products, increasing the acidity of the aqueous phase can be an

effective means to achieve an acceptable shelf-life For example, Gram-negative

patho-gens such as the salmonellae may be controlled by ensuring a pH below 4.0 For

coliforms, an even lower pH is required, or a combination of low pH and low temperature

(The International Commission on Microbiological Specifications for Foods, 1980a)

The type of acid used for lowering the pH is critical, since it is the undissociated molecule

of the organic acid or ester that confers antimicrobial activity Organic acids used as

food preservatives have pKa values of between 3 and 5 (pKa is the pH at which 50% of

the total acid is undissociated) Lowering the pH of a food increases the proportion of

undissociated molecules of an organic acid, thus increasing its effectiveness as an

anti-microbial agent (The International Commission on Microbiological Specifications for

Foods, 1980b) Acetic, citric, lactic, propionic, benzoic, and sorbic acids are the most

commonly used food acidulants and preservatives At pH 4.0, for instance, the proportion

of acetic acid molecules in an undissociated state is over four times that of citric acid,

which reflects the former’s greater effectiveness as a preservative This is well illustrated

by the occurrence of outbreaks of Salmonella in Spain associated with the practice of

using lemon juice instead of acetic acid in mayonnaise in which the importance of

selecting the right acid to maintain a preservative function was simply overlooked (Perez

et al., 1986) In a later study (Perales and Garcia, 1990), it was found that 45% of

mayonnaise made in different restaurants in Spain had a pH greater than 4.5, with 17.5%

using vinegar and lemon, and 2.5% did not use any source of acid, and 60% of the

restaurants surveyed had recipes that allowed Salmonella enteriditis to survive, thus

presenting health risks to consumers The importance of selecting the right acid is even

more important in the case of reduced-fat products, where microbiological risks are that

much greater

Finally, it is important to bear in mind that if strongly acidic notes perceived in a

product adversely affect overall sensory quality, it is possible to design blends that

produce an acceptable flavor profile, while maintaining the preservative function

1.7.4 LEGISLATIVE CONSIDERATIONS

When developing reduced-fat variants, the legislative issues in the country of sale need

to be taken into account This topic is discussed in detail in Chapter 5, but here the issue

of nutritional claims will be outlined briefly due to its importance in product marketing

In the European Union, harmonized provisions for nutrition claims across the member

states has been under consideration for some time now, but final agreement has yet to

be reached The current draft proposes that the term “reduced-fat” can be used if the fat

content is reduced by at least 25% of that present in the standard product, and that the

“low-fat” claim can only be used if not more than 3 g of fat is present per 100 g of

product The term “without fat” would be considered acceptable if the amount of fat did

not exceed 0.15 g per 100 g in a product However, in the absence of harmonized

European Union regulations, national regulations or guidelines need to be adhered to

The U.S regulations for nutrition claims produced by the FDA differ from the current

draft for the European Union in the way the latter two claims are defined The FDA

“low-fat” claim can be used if a reference amount customarily consumed is greater than

30 g, or greater than two tablespoons, and the food contains 3 g or less of fat per reference

amount In cases where the serving size is 30 g or less, or up to two tablespoons, a

“low-fat” claim can be used under the conditions stated above, but providing that 3 g or less

of fat is present in 50 g of the food The “fat-free” claim can be used when the food

contains less than 0.5 g of fat per reference and per labeled serving

A further important difference between current regulations in member states of the

European Union and the U.S is that in the former nutritional labeling remains voluntary

unless a nutritional claim is made for the particular food, whereas the U.S Nutrition

Labeling and Education Act as from May 1994 amended the Federal Food, Drug and

Cosmetic Act to make nutrition labeling mandatory for most foods, and it also became

compulsory to state on the label the amount of calories from fat in addition to the total

amount of calories present Furthermore, where regulations exist regarding compositional

requirements, as with butter, chocolate, or ice cream, the reduced-fat product necessitates

careful naming and labeling from a legal standpoint

1.7.5 PRICING AND MARKETING

The cost of ingredients used to replace fat is another important factor in the development

of low-fat foods More often than not, product development activities are carried out

within financial constraints which require costs of those ingredients not to exceed the

cost of the fat they are supposed to replace Although the initial prices of most fat

mimetics have often been relatively high, competition and economies of scale have

usually brought prices down over time However, in order to survive in the market, an

ingredient will need to have a clear performance advantage over existing alternatives In

this context, it is important to bear in mind that cost analysis is an additional element

that needs to be incorporated into the holistic approach to the development of low-fat

foods already advocated from a technical point of view A complication here is that direct

price comparison between different fat mimetics does not necessarily reflect real cost

differentials since, more often than not, each fat mimetic will require different

adjust-ments in the type and concentration of other ingredients in the formulation in order to

produce an end product of comparable quality This issue is of particular importance

when there are significant differences in the chemical composition of the fat mimetics

being compared, since they would be more likely to have an impact not only on textural

characteristics, but also on flavor and the overall flavor release mechanism, as discussed

in Chapter 4

Finally, the retail price of a low-fat product compared with the standard product will

have an effect on relative sales volumes In this context, it is worth noting that there are

many low-fat variants currently on the market priced at the same level or even lower

than the equivalent full-fat products (Dibb, 1994) This trend can be seen as a positive

initiative of food manufacturers and retailers to achieve a wider public appeal and

increased sales of low-fat products, and further emphasizes the need for a

macro-marketing approach to popularize products that are nutritionally more beneficial

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2 Chapter

Implications of Fat Reduction in the Diet

Debra L Miller and Barbara J Rolls CONTENTS

2.1 Introduction2.2 Background and Significance2.3 Why Is Fat Overeaten?

2.3.1 Palatability2.3.2 Development of a Fat Preference2.3.3 Differences in Fat Preference2.3.3.1 Gender Differences2.3.3.2 Obese/Lean Differences2.3.4 Energy Density

2.3.5 Satiety Value of Fat 2.4 Low-Fat Diet Research2.4.1 Short-Term Fat Manipulations2.4.2 Longer-Term Fat Manipulations2.5 Noncaloric, Synthetic Fat Substitute Research2.6 Fat Replacers and Fat Preference 39

2.7 Population-Based Studies2.8 Conclusions

References

2.1 INTRODUCTION

“Fat-Free,” “Low-Fat,” “Reduced-Fat” — these labels pervade the supermarkets, themedia, and even restaurants and are found on a wide range of products While someindividuals may purchase such products because they prefer the taste, it is likely that

most will do so to bring about improved health and/or body weight changes The question

is then “Will these products be effective in producing the desired results?”

The safety of using fat replacers has received much attention, but comparatively fewdata are available to address the issue of how these products influence human food intakeand energy regulation Until recently there were few studies examining the effects ofvariations in the level of fat in foods on energy intake and body composition This wasbecause until the mid-1980s there was relatively little emphasis on the role of dietaryfat in obesity and related disease states, and the technology for formulating palatablereduced-fat foods was limited Hence, we are only beginning to assess the effectiveness

of such substances in reducing both dietary fat and energy intake

Because of the paucity of relevant literature, nutrition professionals and the generalpublic alike may make assumptions that the use of fat-replaced products will bring aboutautomatic reductions in the high intake of dietary fat in Western society However, weknow very little about how consumers use fat-replaced foods Will fat-replaced foods besubstituted for higher fat versions of foods? (“I use low-fat mayonnaise instead of regularmayonnaise.”) Will they be used as substitutes for “forbidden foods?” (“I’ll eat fat-freepotato chips, but not regular potato chips.”) Will they be used as a license to increaseintake of other types of foods? (“If I use the fat-free salad dressing, I can have a piece

of cheesecake for dessert.”) There is also considerable debate in the scientific communityregarding whether the overconsumption of dietary fat alone leads to negative healthoutcomes, or if it is the resultant increase in overall energy intake due to the overcon-sumption of dietary fat that contributes to these outcomes In many cases, the trickledown message the general public has received is “I can eat as much food as I want aslong as it is low in fat or fat-free.”

This chapter examines these questions and the existing scientific literature regardinglow-fat/fat-replaced foods and diets to determine the efficacy of using fat replacers as astrategy to reduce intake of dietary fat and total energy

2.2 BACKGROUND AND SIGNIFICANCE

In Western societies, high consumption of dietary fat has been linked to obesity, coronaryartery disease, and certain types of cancer, and it is regarded as the top dietary problem

in America (Drewnowski, 1990) Currently, dietary fat comprises nearly 36% of theenergy content of the American diet The guidelines of a number of health organizationsrecommend that no more than 30% of daily energy be derived from dietary fat in order

to reduce the incidence of related morbidity and mortality (National Resource Council,1989; U.S Department of Health and Human Services, 1989)

An obvious method to decrease the percentage of energy from fat is to substitute fat foods for high-fat foods However, it is difficult for many people to limit their foodchoices to the low-fat varieties Controlled laboratory-based experiments indicate thathigh-fat foods are overeaten because they are highly palatable When a considerableamount of fat is removed from the diet, the diet is often bland and monotonous, andeven those whose health status is dependent upon reducing their fat intake, such as cardiacpatients, find it difficult to maintain long-term compliance (Drewnowski, 1990) Recentadvancements in food technology, particularly the development of fat replacers, mayoffer one way of reducing fat and energy consumption while satisfying the preferencefor a high-fat diet The advent of highly palatable reduced-fat or fat-free foods offersconsumers choices that were not previously available, but because there have been fewcontrolled studies of how these products are used by consumers, questions remain abouttheir efficacy in reducing dietary fat intake

low-Several key points to consider when regarding products made with fat replacersinclude:

1 Why do many people eat more dietary fat than is recommended (30% of total energy)and will fat replacers satisfy people’s desire to consume fatty foods?

2 Will eating foods that use fat replacers aid in lowering the amount of fat consumed?That is, will the fat and/or energy reduction be compensated for in subsequent intakes?

3 How will these products be used by the consumer (in place of regularly eaten foods,

as a license to eat previously “forbidden foods,” or to allow for increased consumption

of other foods)?

4 Will individuals learn with repeated experiences that reduced-fat and reduced-energyfoods do not satisfy hunger as well as their high-fat counterparts? If such learningtakes place, will this reduce palatability so that such products are no longer included

or flaky, heavy, viscous, or smooth) and “mouthfeel,” which is described by Drewnowski(1990) as its “distribution in the oral cavity during chewing and swallowing.” Thesetextural and mouthfeel characteristics enhance the richness of food flavor, and stronglyinfluence the palatability of the diet (Drewnowski, 1987; Mela, 1990)

The desirable characteristics that fats endow to food have been identified by variousstudies (Drewnowski et al., 1985; Drewnowski and Greenwood, 1983; Drewnowski et al.,1989) Sensory panels have determined preferences for sweet/fat mixtures such as milkshakes, cake frostings, and ice cream (Drewnowski, 1987; Drewnowski et al., 1985;Drewnowski and Greenwood, 1983) In one study, sweetened skim milk and unsweetenedcream were rated relatively low, but the combination of sugar and fat in sweetened heavycream was highly appealing (Drewnowski et al., 1985) Of course, it is fat, not sugar,that provides the majority of the energy in such a mixture and in other sweet, fat-richdesserts In a survey of U.S military personnel (Meiselman and Waterman, 1985), it wasfound that the most preferred foods were steak, French fries, and milk — which are high

in dietary fat In contrast, some of the least preferred foods in this survey were vegetables,skim milk, diet soda, and cottage cheese, which are very low in fat (Meiselman andWaterman, 1985) Surveys of attitudes toward dietary fat (Shepherd and Stockley, 1985;Shepherd and Stockley, 1987) indicate that highly preferred foods often have a high-fatcontent In these studies, taste is the primary reason given for the selection of a particularfood Since fat imparts characteristics associated with high palatability, high-fat foodsare often chosen

2.3.2 DEVELOPMENT OF A FAT PREFERENCE

Is our preference for high-fat foods innate or learned? Just as the preference for sweettaste, which is thought to be innate, is useful in identifying foods that are safe to eat, an

innate fat preference could have been adaptive for survival by encouraging consumption

of a dense, easily stored energy source for periods of scarcity However, if humans didacquire adaptations that encouraged fat consumption, these adaptations have becomemaladaptive in today’s society, which is characterized by an overabundance of foods(Birch, 1992)

There is some evidence that children display preferences for high-fat foods (Birch,1992; Johnson et al., 1991; Kern et al., 1993) In experiments with high- and low-fatyogurt shakes, Johnson and colleagues (1991) found that preferences for initially novelfoods high in fat content can be learned, and that conditioning of these preferences isthe result of the postingestive consequences of consumption Rozin and Zellner (1985)argue that this type of Pavlovian or associative conditioning is central to the acquisition

of food preferences Because high-fat foods are palatable and satisfying, which arepositive consequences of consumption, children learn to like these foods (Birch, 1992).Such foods are also often used as treats or rewards for children, which may enhance thispreference (Birch, 1992)

The animal literature suggests that fat may be preferred at an early age in rats (Ackroff

et al., 1990; Sclafani, 1990) Ackroff and colleagues (1990) measured fat appetite ininfant rats In this study, which used intake as an index of preference, 12 to 15 day oldpups consumed nearly as much oil emulsion solution as a dilute sucrose solution (0.03 M)and only slightly less than a milk formulation similar to rat’s milk; they concluded thatthe taste for fat was as pleasant to the pups as sweet solutions and mother’s milk.However, in humans, there is no evidence to support the hypothesis that there is aninnate, unlearned preference for fat, and the possibility of such seems unlikely becausethe form and function of fat is not unitary across food systems (Drewnowski, 1987).Furthermore, Drewnowski and colleagues (1991) have shown that there is no relationshipbetween taste preferences for high-fat foods and early age (<10 years) of onset of obesity(thought to be a measure of familial risk); they concluded that environmental as opposed

to familial factors may be more immediate determinants of taste preferences and foodchoice

2.3.3 DIFFERENCES IN FAT PREFERENCE 2.3.3.1 Gender Differences

Just as “Jack Sprat would eat no fat and his wife would eat no lean,” differences in fatpreferences between men and women have been noted anecdotally Recent epidemiolog-ical surveys have provided evidence that there are indeed gender differences in regard

to fat preferences Although both men and women seem to find high-fat foods highlypalatable, men seem to derive the bulk of their dietary fat from red meat, whereas womenderive dietary fats mainly from margarine, whole milk, shortening, and mayonnaise(Block et al., 1985) Women are also more likely than men to express preferences forsweet/fat desserts like cake and ice cream (Block et al., 1985) These gender differencespersist among obese individuals as well Drewnowski and colleagues (1992) surveyedthe favorite foods of obese men and women and found that obese men listed predomi-nantly fat-protein sources (meat dishes) among their favorite foods while obese womenlisted more carbohydrate/fat sources and more sweet foods (doughnuts, cookies, cake,and chocolate)

2.3.3.2 Obese/Lean Differences

It has been proposed that obese persons may have an enhanced preference for high-fatfoods leading to overconsumption of energy dense foods In sensory tests, obese indi-viduals have shown a preference for higher levels of fat in foods than lean individuals

(Drewnowski, 1987) Several investigators have found that body weight was related topreferences for fat In 1985, Drewnowski and colleagues found that obese and formerlyobese individuals preferred higher levels of fat in mixtures of dairy products and sugarthan did lean individuals However, in a 1991 study, Drewnowski found that only a subset

of obese, those with a history of large weight fluctuations, showed an enhanced fatpreference Mela and Sacchetti (1991) found a positive relationship between sensorypreferences for fat in a variety of foods and percent body fat in normal weight subjects

It has been shown that as body fat increased, the percent of energy derived from fatincreased (Miller et al., 1990; Strain et al., 1992), and, in a 3-year longitudinal study(Klesges et al., 1992), high weight gain was associated with high fat intake in both menand women This work taken together indicates that enhanced preferences for fat could

be important in the development and maintenance of obesity; however, no controlled,laboratory-based experiment has looked at this issue directly Additional research isneeded to understand how the sensory qualities of fat and individual differences inpreferences for dietary fat influence human food intake and body composition

2.3.4 ENERGY DENSITY

Dietary fat provides approximately 9 kcal/g compared with 4 kcal/g for carbohydrate orprotein (Burton and Foster, 1991) The relatively high energy density of fat could be afactor in its overconsumption if there is a tendency to eat a certain volume or weight offood For example, 100 g of potato chips (which are typically 60% energy from fat) has

538 kcal, while an equal amount of pretzels (which are typically about 8% energy fromfat or less) has only 375 kcal Several studies which have varied the fat content of foods(Duncan et al., 1983; Lissner et al., 1987; Kendall et al., 1991; Tremblay et al., 1991)have found that subjects consumed a nearly equal volume of food despite differences inenergy density Thus, the more energy-dense, high-fat diets were associated withincreased daily energy intakes when compared to the low-fat diets In some of the studieswhich have manipulated dietary fat (Duncan et al., 1983; Lissner et al., 1987; Kendall

et al., 1991), subjects were given access only to foods within a specified (high or low)fat content, i.e., energy density The results from these studies showed reduced energyintake on low-energy-density diets However, in such situations, there appeared to be atendency to eat a relatively constant amount of food, and it is possible that if theexperiments lasted longer, the amounts of the low-fat foods eaten would graduallyincrease so that daily energy intake would be maintained These studies will be discussed

in more detail in following sections regarding low-fat diet research

2.3.5 SATIETY VALUE OF FAT

Dietary fat may be overconsumed because it does not satisfy hunger as well as othernutrients This hypothesis is related to the physiological consequences of ingested fatsuch as stomach distention, stomach emptying, nutrient absorption, hormonal release,oxidation of nutrients, and so on Several sources suggest that fat and carbohydrate havevery different postingestive consequences Data from experiments measuring postabsorb-tive metabolism suggest that dietary fat is not metabolized as rapidly as carbohydrateand protein (Schutz et al., 1989) Ingested carbohydrates produce rapid rises in bloodglucose (Van Amelsvoort et al., 1989), while fats often depress blood glucose (McHugh

et al., 1975) Thus, depending on the accuracy of the “glucostatic theory,” which suggeststhat the sensation of hunger is maintained until blood glucose levels reach adequatelevels, it is possible that carbohydrates produce more rapid satiety than fats Conversely,there are factors associated with fat intake that may influence satiety as well One ofthese factors is the release of “satiety hormones.”