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How Flavor Works: The Science of Taste and Aroma

Nak-Eon Choi, Jung H. Han

ISBN: 978-1-118-86545-3 December 2014 Wiley-Blackwell 240 Pages


Taste is the number one driving force in the decision to purchase a food product and food consumption is the most critical function for living organisms to obtain the energy and resources essential to their vitality. Flavor and aroma are therefore universally important concepts: intrinsic to human well-being and pleasure, and of huge significance for the multi-trillion dollar global food business.

How Flavor Works: the Science of Taste and Aroma offers a fascinating and accessible primer on the concepts of flavor science for all who have an interest in food and related topics. Professionals and students of food science and technology who do not already specialize in flavor science will find it a valuable reference on a topic crucial to how consumers perceive and enjoy food products. In this regard, it will also be of interest to product developers, marketers and food processors. Other readers with a professional (eg culinary and food service) or personal interest in food will also find the book interesting as it provides a user-friendly account of the mechanisms of flavor and aroma which will provide new insights into their craft.

Preface xi

About the Authors xiii

1 What is Taste? 1

Four basic tastes, as proposed by Aristotle 5

Taste is complex 7

Most food ingredients are tasteless, odorless, and colorless 7

Variations in odor during fermentation and aging due to changes in molecular weight 10

2% is not a small amount 12

2 The Origins of Taste: Why do we Taste? 15

Sweetness is for identifying energy sources (Carbohydrates) 15

Umami is a tool used to search for proteins 22

Carbohydrates are for sweetness, proteins are for umami, but what are lipids for? 28

Saltiness: the ocean was the source of all life 30

The role of salt in cooking is not merely to provide saltiness 33

The contrast effect 33

The suppression effect 34

Acidity monitors the biological metabolism 34

Bitterness: if it’s bitter, spit it out! 37

Some people enjoy bitter tastes 39

The reason we consume caffeine despite its bitterness 40

The olfactory sense is the dominant sensory perception of animals 42

The search for food 42

Avoid danger! 43

Know who it is! 44

Find a mate! 45

References 46

3 Taste is General Science 47

Taste improves with harmonized combinations 48

The taste of meals = saltiness + umami + savory flavor 48

The taste of dessert (and fruit) = sweetness + sourness + sweet odor 49

Tastes influence odors 50

Food has to be dissolved for us to taste and chewed to enhance the taste 52

The main ingredients influence taste and odor 53

Sound has an influence on taste 55

Visuals, colors, and food styles 55

Why does color exist? 57

The basic structure of pigment: why are there no naturally blue foods? 59

Perception varies with individual differences and conditions 61

Differences due to age and sex 61

Individual variation is also significant 63

Differences due to race and history 65

The preference for smells is constantly changing 66

References 67

4 How do we Smell Odors? 69

Olfactory receptors are G-protein coupled receptors 69

G-Receptors differentiate isomers, resulting in different odors 71

G-Receptors perceive multiple chemical substances 73

G-Receptors work simply as on/off switches 75

Depending on the binding affinity to receptors, similar molecules can be recognized as completely different tastes and odors 76

The broad spectrum of the olfactory sense 77

The transduction of sensory signals 79

Olfactory fatigue is also a functional activity for life 80

The recognition and integration of perceptions 82

Parts of the brain 82

Continuous circulations in the loop 83

G-Receptors can perceive light 85

Understanding G-receptors can provide many answers 85

Pheromones are not mysterious substances 89

References 89

5 What Creates Smell? 91

Odorous molecules are mainly created by plants 91

Why do plants produce aroma compounds? 92

Attracting bacteria, insects, and animals 92

As a defensive mechanism 94

Attacking tools 95

Coincidental byproducts 96

Animals generally smell odorants, not produce them 97

Animal-origin raw materials 97

Unconditional surrender to pheromones 98

Is body odor a coincidental byproduct? 99

Most flavors that we enjoy are created by cooking 100

Flavor production by enzymatic or microbial fermentations 101

Flavor production by heat processes 104

Flavor production by pyrolysis: smoke flavor 106

Compound flavor: creation of new flavors by mixing various odors 107

References 108

6 Technological Advancements Brought about by the Love of Flavors 109

Why do people combine flavors? 112

How many flavors are there in the world and how many ingredients are required to make all of these flavors? 114

How many odorous chemicals are needed to create a tomato flavor? 116

Perfumers and flavorists create flavors 119

Olfactory training: flavorists must first distinguish odorous chemicals before creating compound flavors 120

Compounding flavors: aromas are completed through imagination 124

To become a perfumer, a heavy smoking habit and age do not matter 126

The important factor is harmony 126

Applications of compound flavors 128

Types of odorants 128

Synthetic flavors versus natural flavors: which is safer? 129

Advantages and limitations of natural flavors 137

Advantages and limitations of compound flavors 138

References 139

7 How Flavors Influence us 141

Brain development began with the olfactory sense 141

The human olfactory sense is less sensitive and inarticulate 144

Humans’ sense of smell has degenerated greatly 145

Proust phenomenon: odor-evoked autobiographical memory 146

Sensorial preference changes destinies 147

Do silkworms only eat mulberry leaves? 148

Humans live with smells 149

Stage of development 149

What happens if you can no longer feel taste or smell? 150

Are humans free from pheromones 152

The healing power of aromas 156

Aromatherapy 157

Aromachology 158

Phytoncide 159

Is geosmin foul or pleasant? 161

Multiple chemical sensitivity (mcs): there are people who are really intolerant to odorous chemicals 162

References 164

8 Taste is Regulated by Flavor, and Flavor is Regulated by the Brain 167

The sense of smell is directly connected to the imbic system, in other words, to survival and emotion 167

Neuroplasticity in the brain 169

Is synesthesia a malfunction or a blessing? 170

Taste is a typical phenomenon of synesthesia and neuroplasticity 172

Orbitofrontal cortex: where sight, taste, smell, and touch meet 173

Taste is a part of pleasure, and that pleasure becomes a part of taste 174

Experience affects taste: familiar foods are preferred 176

The feeling of disgust can be acquired through learning 177

Taste is affected by temperature 178

Price: expectation affects the taste 179

Prejudices are effective at distorting perceived senses 180

Even the data from an expert research firm cannot promise success in sales 181

Sensorial perception is an illusion 183

Taste and aroma do not exist 185

A good product image makes it taste better 185

References 187

9 The Future of Taste and Aroma 189

Raw ingredient resources gradually become simplified and their original aromas disappear 189

More scientific technologies will be incorporated into the culinary arts 190

What is the difference between cooking and the processing of foods? 192

Aroma-releasing television or movies 194

Is the taste of processed foods inferior to that of natural foods? 196

Is it true that obsessions with flavors and seasonings have decreased? 199

Do technological developments of taste modifications induce obesity or become a key solution to the problem? 201

Technology of satiety: technology of cognitive science for taste and olfactory senses is the technology of the future 202

Satiety control 203

The era of supernormal stimuli 205

References 206

10 Concluding Remarks 207

References 211

Index 213


“Anyone with an interest in foods, flavours or fragrances (dare I say most of us!) will definitely ‘sniff out’ something of value from this book.”  (Chemistry in Australia, 1 October 2015)

“Other readers with a professional (e.g. culinary and food service) or personal interest in food will also find the book interesting as it provides a user-friendly account of the mechanisms of flavor and aroma which will provide new insights into their craft.”  (Biotech, Agro, Soc & Env, 1 September 2015)