Flavor, Satiety and Food Intake

This unique book provides a comprehensive review of the latest science on a key aspect of appetite control. It brings together contributions by leading researchers worldwide who approach this complex, multifaceted issue from a variety of differing perspectives, including those of food science, psychology, nutrition, and medicine, among others. 

It is well known that products that require greater oral processing tend to be more sating. At the same time, the orosensory exposure hypothesis holds that flavor and texture in the mouth are critical in determining meal-size. They may act as key predictors of nutritional benefits and so promote better processing of foods. These two related ideas are at the forefront of current thinking on flavor-satiety interactions. Yet, until Flavor, Satiety and Food Intake no book has offered an integrated treatment of both concepts.  The only single-source reference of its kind, it brings health professionals, product developers, and students up to speed on the latest thinking and practices in this fascinating and important area of research.

• Provides readers with a unique and timely summary of critical recent developments in research on the impact of flavor on satiety
• Explores a topic of central importance both for food professionals seeking to develop healthier products and health professionals concerned with obesity and over-eating
• Brings together relevant topics from the fields of food science, psychology, nutrition and medicine

Flavor, Satiety and Food Intake provides product developers with valuable information on how to integrate sensory evaluation with product formulation and marketing. It will also serve as a useful resource for health professionals and is a must-read for students of a range of disciplines in which appetite and satiety are studied. 

• Language: English
• Publisher: Wiley
• Release date: Apr 5, 2017
• ISBN: 9781119044925

Book preview

CONTENTS

Cover

Series Page

Title Page

Copyright

Titles in the IFT Press Series

List of Contributors

Preface

Acknowledgements

Chapter 1: Introducing Sensory and Cognitive Influences on Satiation and Satiety

1.1 Appetite Control in Context

1.2 Satiation and Satiety: A Brief Overview

1.3 Sensory Influences on Satiation and Satiety: A Brief History

1.4 New Directions

1.5 Concluding Remarks

References

Chapter 2: Satiety and Liking Intertwined

2.1 Chapter Overview

2.2 Liking

2.3 Postingestive Satiety

2.4 The Five-Factor Satiety Questionnaire

2.5 The Intertwining of Liking and Satiety

2.6 Sensory-Specific Satiety, A Relative Change in Liking

2.7 Summary

References

Chapter 3: The Chemical Senses and Nutrition: The Role of Taste and Smell in the Regulation of Food Intake

3.1 Introduction

3.2 The Role of Taste in Food Intake

3.3 The Role of Odour in Food Intake

3.4 Discussion

References

Chapter 4: Sweetness and Satiety

4.1 Sweet Taste Detection

4.2 Sweetness and Satiety

4.3 Sweetness and Reward

4.4 Summary and Considerations

References

Chapter 5: Reinforcing Value of Food, Satiety, and Weight Status

5.1 Introduction

5.2 Reinforcing Value

5.3 How is the Reinforcing Value of Food Measured?

5.4 Relationship between Food Reinforcement and AD Libitum Energy Intake

5.5 Relationship between the Reinforcing Value of Food and Obesity

5.6 Satiety and Satiation

5.7 How does the Reinforcing Value of Food Influence Satiation and Satiety?

5.8 Can We Alter the Reinforcing Value of Food?

5.9 Implications of Reinforcing Value of Food Research

5.10 Summary and Conclusions

References

Chapter 6: Cognitive and Sensory Enhanced Satiety

6.1 Introduction

6.2 Cognitions and Consumption

6.3 Oro-Sensory Influences on Satiety

6.4 Case Study: Optimising Beverages for Satiety

6.5 Conclusions

References

Chapter 7: Umami and the Control of Appetite

7.1 Introduction

7.2 Umami Taste Perception

7.3 Where in the Diet Does Glutamate Occur?

7.4 Umami, Palatability and the Stimulation of Appetite

7.5 Umami, Satiation and Satiety

7.6 The Uniqueness of Umami: A Biphasic Impact on Appetite

7.7 Summary

References

Chapter 8: Colour, Flavour and Haptic Influences on Satiety

8.1 Introduction

8.2 Colour Contributions to the Perception and Consumption of Food

8.3 Haptic Influences on Food Perception and Satiety

8.4 Concluding Notes

References

Chapter 9: Engineering Satiety

9.1 Introduction

9.2 Emulsions

9.3 Viscous, Gelling and Fermentable Polysaccharides

9.4 Conclusion

References

Index

End User License Agreement

List of Tables

Table 2.1

Table 7.1

Table 7.2

Table 9.1

List of Illustrations

Figure 2.1

Figure 2.2

Figure 2.3

Figure 2.4

Figure 2.5

Figure 2.6

Figure 2.7

Figure 2.8

Figure 2.9

Figure 3.1

Figure 3.2

Figure 3.3

Figure 4.1

Figure 4.2

Figure 5.1

Figure 5.2

Figure 5.3

Figure 5.4

Figure 5.5

Figure 6.1

Figure 6.2

Figure 6.3

Figure 6.4

Figure 6.5

Figure 6.6

Figure 6.7

Figure 6.8

Figure 6.9

Figure 7.1

Figure 7.2

Figure 7.3

Figure 7.4

Figure 8.1

Figure 8.2

Figure 9.1

Figure 9.2

The IFT Press series reflects the mission of the Institute of Food Technologists — to advance the science of food contributing to healthier people everywhere. Developed in partnership with Wiley, IFT Press books serve as leading - edge handbooks for industrial application and reference and as essential texts for academic programs. Crafted through rigorous peer review and meticulous research, IFT Press publications represent the latest, most significant resources available to food scientists and related agriculture professionals worldwide. Founded in 1939, the Institute of Food Technologists is a nonprofit scientific society with 18,000 individual members working in food science, food technology, and related professions in industry, academia, and government. IFT serves as a conduit for multidisciplinary science thought leadership, championing the use of sound science across the food value chain through knowledge sharing, education, and advocacy.

IFT Press Advisory Group

Baris Ates

Nicolas Bordenave

Ravi Chermala

YiFang Chu

Deepti Dabas

Chris Doona

Chris Findlay

Maria Jose Frutos-Fernandez

Elsina Hagan

Jung Hoon Han

Shane McDonald

Gordon Robertson

Shahin Roohinejad

Sam Saguy

Fereidoon Shahidi

Herbert Stone

Yael Vodovotz

Jared Willbergh

Bob Swientek (IFT)

Melanie Bartelme (IFT)

David McDade (Wiley)

Flavor, Satiety and Food Intake

Edited by

Beverly Tepper

Rutgers University, NJ, USA

Martin Yeomans

University of Sussex, UK

Wiley Logo

Wiley Logo

This edition first published 2017

© 2017 by John Wiley & Sons Ltd and the Institute of Food Technologists

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions.

The right of Beverly Tepper and Martin Yeomans to be identified as the authors of the editorial material in this work has been asserted in accordance with law.

Registered Offices

John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA

John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK

Editorial Office

9600 Garsington Road, Oxford, OX4 2DQ, UK

The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK

For details of our global editorial offices, customer services, and more information about Wiley products visit us at www.wiley.com.

Wiley also publishes its books in a variety of electronic formats and by print-on-demand. Some content that appears in standard print versions of this book may not be available in other formats.

Limit of Liability/Disclaimer of Warranty

The publisher and the authors make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of fitness for a particular purpose. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for every situation. In view of ongoing research, equipment modifications, changes in governmental regulations, and the constant flow of information relating to the use of experimental reagents, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each chemical, piece of equipment, reagent, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions. The fact that an organization or website is referred to in this work as a citation and/or potential source of further information does not mean that the author or the publisher endorses the information the organization or website may provide or recommendations it may make. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this works was written and when it is read. No warranty may be created or extended by any promotional statements for this work. Neither the publisher nor the author shall be liable for any damages arising here from.

Library of Congress Cataloging-in-Publication Data

[9781119044895]

Names: Tepper, Beverly J., editor. | Yeomans, Martin, editor.

Title: Flavor, satiety and food intake / edited by Beverly Tepper, Rutgers University, NJ, US, Martin Yeomans, University of Sussex, UK.

Description: Chichester, UK ; Hoboken, NJ, USA : John Wiley & Sons, Inc., 2017. | Includes bibliographical references and index.

Identifiers: LCCN 2016057158| ISBN 9781119044895 (cloth) | ISBN 9781119044925 (epub) 9781119044932 (pdf)

Subjects: LCSH: Appetite. | Flavor. | Taste. | Nutrition.

Classification: LCC QP136 .F54 2017 | DDC 612.3–dc23 LC record available at https://lccn.loc.gov/2016057158

Cover design: Wiley

Cover images: (Food) © Annabelle Breakey/Gettyimages;

(Brain) © Henrik5000/Gettyimages;

(People) © Monkey Business Images/Shutterstock

Titles in the IFT Press Series

Accelerating New Food Product Design and Development (Jacqueline H. Beckley, Elizabeth J. Topp, M. Michele Foley, J.C. Huang, and Witoon Prinyawiwatkul)

Advances in Dairy Ingredients (Geoffrey W. Smithers and Mary Ann Augustin)

Anti-Ageing Nutrients: Evidence-based Prevention of Age-Associated Diseases (Deliminda Neves)

Bioactive Compounds from Marine Foods: Plant and Animal Sources (Blanca Hernández-Ledesma and Miguel Herrero)

Bioactive Proteins and Peptides as Functional Foods and Nutraceuticals (Yoshinori Mine, Eunice Li - Chan, and Bo Jiang)

Biofilms in the Food Environment, second Edition (Anthony L. Pometti III and Ali Demicri)

Bitterness: Perception, Chemistry and Food Processing (Michel Aliani and Michael N.A. Eskin)

Calorimetry in Food Processing: Analysis and Design of Food Systems (G ö n ü l Kaletunç)

Coffee: Emerging Health Effects and Disease Prevention (YiFang Chu)

Flavor, Satiety and Food Intake (Beverly Tepper, Martin Yeomans)

Food Carbohydrate Chemistry (Ronald E. Wrolstad)

Food Carotenoids: Chemistry, Biology and Technology (Delia B. Rodriguez-Amaya)

Food Industry Design, Technology & Innovation (Helmut Traitler, Birgit Coleman and Karen Hofmann)

Food Ingredients for the Global Market (Yao - Wen Huang and Claire L. Kruger)

Food Irradiation Research and Technology, second edition (Christoper H. Sommers and Xuetong Fan)Foodborne Pathogens in the Food Processing Environment: Sources, Detection and Control (Sadhana Ravishankar, Vijay K. Juneja, and Divya Jaroni)

Food Oligosaccharides: Production, Analysis and Bioactivity (F. Javier Moreno and Maria Luz Sanz

Food Texture Design and Optimization (Yadunandan Dar and Joseph Light)

High Pressure Processing of Foods (Christopher J. Doona and Florence E. Feeherry)

Hydrocolloids in Food Processing (Thomas R. Laaman)

Improving Import Food Safety (Wayne C. Ellefson, Lorna Zach, and Darryl Sullivan)

Innovative Food Processing Technologies: Advances in Multiphysics Simulation (Kai Knoerzer, Pablo Juliano, Peter Roupas, and Cornelis Versteeg)

Mathematical and Statistical Methods in Food Science and Technology (Daniel Granato and Gastón Ares)

Membrane Processes for Dairy Ingredient Separation(Kang Hu and James Dickson)

Microbial Safety of Fresh Produce (Xuetong Fan, Brendan A. Niemira, Christopher J. Doona, Florence E. Feeherry, and Robert B. Gravani)

Microbiology and Technology of Fermented Foods (Robert W. Hutkins)

Multiphysics Simulation of Emerging Food Processing Technologies  (Kai Knoerzer, Pablo Juliano, Peter Roupas and Cornelis Versteeg)

Multivariate and Probabilistic Analyses of Sensory Science Problems (Jean - Fran ç ois Meullenet, Rui Xiong, and Christopher J. Findlay

Nanoscience and Nanotechnology in Food Systems (Hongda Chen)

Nanotechnology and Functional Foods: Effective Delivery of Bioactive Ingredients (Cristina Sabliov, Hongda Chen and Rickey Yada)

Natural Food Flavors and Colorants, second edition (Mathew Attokaran)

Nondestructive Testing of Food Quality (Joseph Irudayaraj and Christoph Reh)

Nondigestible Carbohydrates and Digestive Health (Teresa M. Paeschke and William R. Aimutis)

Nonthermal Processing Technologies for Food (Howard Q. Zhang, Gustavo V. Barbosa - C á novas, V.M. Balasubramaniam, C. Patrick Dunne, Daniel F. Farkas, and James T.C. Yuan)

Nutraceuticals, Glycemic Health and Type 2 Diabetes (Vijai K. Pasupuleti and James W. Anderson)

Organic Meat Production and Processing (Steven C. Ricke, Ellen J. Van Loo, Michael G. Johnson, and Corliss A. O' Bryan)

Packaging for Nonthermal Processing of Food (Jung H. Han)

Practical Ethics for the Food Professional: Ethics in Research, Education and the Workplace (J. Peter Clark and Christopher Ritson)

Preharvest and Postharvest Food Safety: Contemporary Issues and Future Directions (Ross C. Beier, Suresh D. Pillai, and Timothy D. Phillips, Editors; Richard L. Ziprin, Associate Editor)

Processing and Nutrition of Fats and Oils (Ernesto M. Hernandez and Afaf Kamal - Eldin)

Processing Organic Foods for the Global Market (Gwendolyn V. Wyard, Anne Plotto, Jessica Walden, and Kathryn Schuett)

Regulation of Functional Foods and Nutraceuticals: A Global Perspective (Clare M. Hasler)

Resistant Starch: Sources, Applications and Health Benefits (Yong - Cheng Shi and Clodualdo Maningat)

Sensory and Consumer Research in Food Product Design and Development (Howard R. Moskowitz, Jacqueline H. Beckley, and Anna V.A. Resurreccion)

Spray Drying Techniques for Food Ingredient Encapsulation (C. Anandharamakrishnan and Padma Ishwarya S.)

Sustainability in the Food Industry (Cheryl J. Baldwin)

Thermal Processing of Foods: Control and Automation (K.P. Sandeep)

Trait - Modified Oils in Foods (Frank T. Orthoefer and Gary R. List)

Water Activity in Foods: Fundamentals and Applications (Gustavo V. Barbosa - Cánovas, Anthony J. Fontana Jr., Shelly J. Schmidt, and Theodore P. Labuza)

Whey Processing, Functionality and Health Benefits (Charles I. Onwulata and Peter J. Huth)

List of Contributors

Sanne Boesveldt, Ph.D.

Wageningen University and Research Centre, the Netherlands

Cees de Graaf, Ph.D.

Division of Human Nutrition, Wageningen University and Research Centre, Wageningen, the Netherlands

Betina Piqueras Fiszman, Ph.D.

Marketing and Consumer Behaviour Group, Wageningen University, Wageningen, the Netherlands

Pleunie Hogenkamp, Ph.D.

Department of Neuroscience, Uppsala University, Uppsala, Sweden

Aaron Mitchell Lett, Ph.D.

School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, UK

Una Masic, Ph.D.

Department of Psychological Sciences, University of Liverpool, Liverpool, UK

Keri McCrickerd, Ph.D.

Clinical Nutrition Research Centre, Centre for Translational Medicine, Yong Loo Lin School of Medicine, Singapore

Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore

Jennifer Norton, Ph.D.

School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, UK

Jennifer L. Temple, Ph.D.

Associate Professor, Departments of Exercise and Nutrition Sciences and Community Health and Health Behavior, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY

Zata Vickers, Ph.D.

Professor, Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN

Martin R. Yeomans, Ph.D.

School of Psychology, University of Sussex, Brighton, UK

Preface

The food industry faces competing demands from different quarters: from consumers who want products that are highly palatable yet meet a growing number of health needs; from legislators who seek to reduce the levels of food components that are seen as deleterious for long-term health (e.g. sugar, fat and salt); and from health professionals battling a worldwide epidemic in obesity and related health problems.

To balance these needs, all of those with an interest in the production and promotion of more healthy food options need to stay informed on recent advances in our fundamental understanding of the complicated inter-relationships between our sensory experience of food and its subsequent effects on our appetite and body weight. By bringing together key researchers who approach these complex issues from very different perspectives, this book provides the reader with a unique and timely summary of key recent developments in the impact of flavour on satiety.

The benefit to the reader will vary between user groups. Students exposed to a disparate range of courses which encompass appetite from different perspectives (food science, dietetics, nutrition, psychology, etc.) will benefit from concise summaries of key developments in this area, something that they cannot get from reading the broader primary research material. Product developers will get insights into novel ways of integrating sensory evaluation with product formulation and marketing to help develop new products that are better suited to consumer needs and aspirations. Health professionals (such as dieticians etc.) will benefit from having a single reference source to bring their knowledge in this area up to speed as part of their continued professional development.

Beverly Tepper

Martin Yeomans

Acknowledgements

The impetus for this book arose from the enthusiastic response to the symposium entitled ‘What is the Measure of Your Pleasure – Understanding the Relationship Between Satiety and Liking’, presented at the 2013 Institute of Food Technologists Annual Meeting in Chicago, Illinois (organized and moderated by Beverly J Tepper and Katherine Nolen Oftedal). The three featured speakers, Zata Vickers, PhD (Foods and Nutrition, University of Minnesota); Betina Pequeras-Fiszman, PhD, (Experimental Psychology, University of Oxford, UK) and Martin Yeomans, DPhil (Psychology, University of Sussex, UK) generously agreed to contribute chapters to this volume, and their combined works serve as the foundation for this text. The editors gratefully acknowledge their participation in this effort and extend our thanks to all our contributors.

Beverly Tepper

Martin Yeomans

1

Introducing Sensory and Cognitive Influences on Satiation and Satiety

Martin R. Yeomans, Ph.D.

1.1 Appetite Control in Context

The worldwide increase in incidence of overweight and obesity represents one of the biggest public health challenges of recent times. Statistics on obesity are startling: the proportion of the population in the United States who meet World Health Organisation (WHO) criteria for obesity have risen from around 7% in 1985 to 30% in 2015. In 2014, more than one in four people were obese in countries as diverse as New Zealand, Mexico, Canada, Hungary and Chile. The WHO estimated that by 2014 39% of the world's population met the criteria for overweight, and 13% were obese, with more people overweight than malnourished for the first time in recorded history.

These statistics make understanding causes of weight gain an imperative. Weight gain is the consequence of storage of excess nutrients when there is an imbalance between energy intake and energy expenditure. Thus when intake of sources of energy in the diet, primarily fat and carbohydrate, exceeds short-term energy needs (the sum of basal metabolism, thermogenesis and energy needed for exercise and cognitive activity), the excess is stored. Most of the excess is converted to body fat, either directly by processing of ingested fat or through conversion of excess carbohydrate into fat by the liver. However, excess intake arises only when factors that encourage short-term intake are not regulated by the systems involved in promoting energy expenditure and, crucially in the context of this book, inhibiting further food intake. It is noteworthy that despite the worldwide increase in obesity, many consumers maintain a stable weight. This implies that even in the modern obesogenic environment it is possible to maintain an appropriate balance between energy input and output, but that individual differences in sensitivity to external cues promoting intake and homeostatic processes regulating appetite make some individuals prone to over-consumption. Since humans typically eat at prescribed times dictated by cultural convention, it has been argued that understanding the processes that lead to suppression of appetite after a meal are key to understanding how altering the food environment may help promote individual appetite regulation [1–5].

1.2 Satiation and Satiety: A Brief Overview

The modern interpretation of the terms satiation and satiety are most clearly encapsulated in the description of processes involved in appetite control commonly referred to as the satiety cascade [6]. In that descriptive model, satiation was defined as the processes that bring a meal to an end and satiety as the suppression of appetite post-ingestion. This specific interpretation of satiation and satiety is now widely accepted. The chapters in this book all examine aspects of two types of influence on satiation and satiety. The primary focus here is on how the sensory features of the foods and drinks we ingest influence the decisions that lead to meal termination (satiation) and also modify the processes that suppress appetite after ingestion (satiety). There are also chapters that highlight more cognitive elements that also modify both the interpretation of sensory cues and satiation and satiety more directly. Although models such as the satiety cascade fully recognised the importance of these cognitive and sensory influences, the majority of research on satiety remains focussed on physiological signals arising in the gut as a consequence of food ingestion. However, an understanding of these gut-derived signals is needed in order to put the main chapters in this volume into a broader context. The reader can find a more detailed description and discussion of these gut-based satiety signals in one of a number of more detailed reviews [3,7–10].

The view of satiety most commonly described when discussing the role of gut-based satiety signals sees the gut effectively as a sensor that sends signals about the nutrients it can detect to the brain [3,11,12]. This gut-to-brain signalling is clearly a major component of the physiological basis of satiety experienced post-ingestion. However, what the present volume clearly demonstrates is that these gut-derived physiological signals are only part of the story and that both cognitive and sensory cues at the point of ingestion can clearly modify the way the body experiences satiety from the same set of nutrients depending on the context in which those nutrients were ingested. Thus understanding gut-derived physiological signals is an important component of satiety, but they can only be interpreted in the context of all signals relating to ingestion, including those arising from both the sensory experience of food and beliefs about the likely effects of that food on appetite.

What then are the principle gut-derived signals? Arguably the most important signals are specific peptides released in the gut in response to specific nutrient signals and whose purpose is to regulate the passage of food though the gut to optimise digestion and nutrient absorption. One key aspect of that control process is to modify ingestion to ensure an appropriate supply of nutrients, and it is likely that the gut-based satiety signals have evolved at least partly for that reason. The first such signal to be identified was cholecystokinin, first shown to modify ingestion in rats in 1973 [13], but since then many more gut-based signals have been identified, most of which appear to have roles in suppressing appetite (and are described as satiety signals), including glucagon-like peptide 1 (GLP1), polypeptide YY (PYY), oxyntomodulin (OXM) and pancreatic polypeptide (PP). A further gut-derived signal, ghrelin, has the opposite effect, increasing the experience of appetite in humans and increasing food intake in humans [14–17] and other species [18,19]: see Hussain and Bloom and Guyenet and Schwartz [12,20] for recent reviews. Thus ghrelin stands apart as the only gut-derived hormonal hunger signal. The evidence supporting specific roles of these different gut signals in satiety typically involves a combination of studies in animals showing reduced food intake after administration of these compounds, evidence that such effects are consistent with a normal cessation of feeding rather than an indirect effect through malaise, and studies showing both reduced rated appetite and food intake in humans, again in the absence of any confounding malaise: this evidence has been reviewed at length by many authors [3,7,10,21], and a full review is beyond the scope of this introduction. What the current volume does do, however, is put these physiological satiety cues into the broader context of other signals associated with food ingestion, particularly those derived from the sensory characteristics of foods and drinks.

1.3 Sensory Influences on Satiation and Satiety: A Brief History

The chapters in this volume provide timely summaries of recent progress in understanding sensory and cognitive influences on satiation and satiety that build on ideas founded in classic studies in recent decades. Arguably the most influential concept during this time has been sensory specific satiety (SSS), and this concept is discussed from different perspectives in the chapters by Vickers (Chapter 2), De Graaf and Boesveldt (Chapter 3) and Piqueras Fiszman (Chapter 8). Sensory specific satiety is a concept founded in changes in liking for foods as a consequence of ingestion. The key observation is that liking for a food that is being consumed decreases, but liking for other foods which are not being consumed is maintained. The original observations came from studies in rats by the pioneering appetite researcher Jacques Le Magnen [22]: he observed that rats ate considerably more when provided with a variety of different-flavoured foods than when offered just a single food. The actual term SSS, however, came from seminal studies by Barbara and Edmund Rolls showing how rated liking for a consumed food decreased, but liking was unaltered for other non-consumed foods [23]. Although the change in liking occurs during ingestion and so may be better thought of as relating to satiation than satiety in our modern classification of appetite control, the term SSS has become such a clear label for this phenomenon that it remains. The key finding that there were neural correlates of SSS in the responses of single neurones in the lateral hypothalamus of monkeys [24] provided strong support for the idea that SSS is a key component of satiation and is often viewed as one of three key sensory or cognitive influences on meal size (the others being conditioned satiety and gustatory alliesthesia). SSS remains the most widely cited explanation for the role of variety in increasing food intake [25–28]. Given its importance in this context, SSS is an important element of this book.

Alliesthesia, or negative gustatory alliesthesia, to use its full name, was a concept introduced in 1968 by Michel Cabanac to discuss how liking for specific sensory characteristics of a food, most notably a sweet taste, was modified by homeostatic signals relating to internal state [29]. His fundamental argument was that liking for signals relating to energy, such as sweet taste, was greater when hungry than when sated [30], and Cabanac published extensively on this. (See Cabanac [31–33]). Although the term alliesthesia is used much less often by current researchers, key questions around the role of sweetness in satiety have become very important, and the role of sweetness in particular is consequently discussed in two chapters here: De Graaf and Boesveldt (Chapter 3) discuss sweetness more broadly from a perspective of sensory signals influencing appetite, while Hogenkamp (Chapter 4) asks more specifically the extent to which sweetness acts as a satiety signal, specifically focussing on the effects of low-energy sweeteners. Several recent developments make the issue of sweetness particularly relevant, most dramatically the claim that sugar may be addictive [34–36] and cause over-eating [37,38], and that as a consequence, several countries are introducing specific financial disincentives to dissuade over-consumption of sugar-sweetened beverages in particular (sugar taxes). Although the focus on sweetness has moved on from the early discussion of alliesthesia, sweetness rightly remains a critical area of discussion in relation to sensory influences on satiety.

Alliesthesia was founded in the homeostatic tradition which considered how expression of liking for foods was related to energetic needs. Since the concept of alliesthesia was developed, there has been increasing interest in the rewarding nature of eating. In its extreme form, an alliesthesia hedonic evaluation was seen, at least in part, as an expression of the need for a