Foreword xiii
List of Contributors xv
Acknowledgements xvii
Abbreviations xix
1 Volatiles - An Interdisciplinary Approach 1
Andreas Herrmann
1.1 Introduction 1
1.2 Geraniol - A Typical Example 2
1.3 Conclusion 8
References 8
2 Biosynthesis and Emission of Isoprene, Methylbutanol and Other Volatile Plant Isoprenoids 11
Hartmut K. Lichtenthaler
2.1 Introduction 11
2.2 Plant Isoprenoids 12
2.3 Two IPP-Yielding Pathways in Plants 15
2.4 Prenyl Chain Formation and Elongation 16
2.5 Compartmentation of Plant Isoprenoid Biosynthesis 16
2.6 The Enzyme Steps of the Plastidic DOXP/MEP Pathway of IPP Formation 17
2.7 Cross-Talk Between the Two IPP Biosynthesis Pathways 19
2.8 Biosynthesis and Emission of Volatile Isoprene at High Irradiance 22
2.8.1 Regulation of Isoprene Emission 25
2.9 Inhibition of Isoprene Biosynthesis 26
2.9.1 Fosmidomycin and 5-Ketoclomazone 26
2.9.2 Diuron 27
2.10 Inhibition of Carotenoid and Chlorophyll Biosynthesis by Fosmidomycin and 5-Ketoclomazone 27
2.11 Biosynthesis and Emission of Methylbutenol at High Irradiance 28
2.12 Source of Pyruvate for Isoprene and Methylbutenol Biosynthesis 29
2.13 Branching Point of DOXP/MEP Pathway with Other Metabolic Chloroplast Pathways 30
2.14 Is There a Physiological Function of Isoprene and MBO Emission? 31
2.15 Biosynthesis and Emission of Monoterpenes, Sesquiterpenes and Diterpenes 33
2.15.1 Monoterpenes 35
2.15.2 Diterpenes 36
2.15.3 Sesquiterpenes 36
2.16 Some General Remarks on the Regulation of Terpene Biosynthesis in Plants 36
2.17 Volatile Terpenoids as Aroma Compounds of Wine 37
2.18 Function of Terpenes in Plant Defence 38
2.19 Conclusion 38
Acknowledgements 39
References 40
3 Analysis of the Plant Volatile Fraction 49
Patrizia Rubiolo, Barbara Sgorbini, Erica Liberto, Chiara Cordero and Carlo Bicchi
3.1 Introduction 49
3.2 Sample Preparation 50
3.2.1 'Liquid' Phase Sampling 51
3.2.2 Headspace Sampling 51
3.2.3 Headspace-Solid Phase Microextraction 52
3.2.4 In-Tube Sorptive Extraction 54
3.2.5 Headspace Sorptive Extraction 55
3.2.6 Static and Trapped Headspace 56
3.2.7 Solid-Phase Aroma Concentrate Extraction 56
3.2.8 Headspace Liquid-Phase Microextraction 56
3.2.9 Large Surface Area High Concentration Capacity Headspace Sampling 59
3.3 Analysis 59
3.3.1 Fast-GC and Fast-GC-qMS EO Analysis 61
3.3.2 Qualitative Analysis 65
3.3.3 Quantitative Analysis 66
3.3.4 Enantioselective GC 70
3.3.5 Multidimensional GC Techniques 75
3.4 Further Developments 76
3.5 Conclusion 85
Acknowledgements 87
References 87
4 Plant Volatile Signalling: Multitrophic Interactions in the Headspace 95
Andre Kessler and Kimberly Morrell
4.1 Introduction 95
4.2 The Specificity and Complexity of Herbivore-Induced VOC Production 97
4.2.1 Plant Endogenous Wound Signalling 99
4.2.2 Herbivore-Derived Elicitors of VOC Emission 102
4.3 Ecological Consequences of VOC Emission 104
4.3.1 Within-Plant Defence Signalling 104
4.3.2 Herbivore-Induced VOC Emission as Part of a Metabolic Reconfiguration of the Plant 105
4.3.3 Herbivores Use VOCs to Select Host Plants 107
4.3.4 VOCs as Indirect Defences Against Herbivores 108
4.3.5 VOCs in Plant-Plant Interactions 111
4.4 Conclusion 112
Acknowledgements 114
References 114
5 Pheromones in Chemical Communication 123
Kenji Mori
5.1 Introduction 123
5.1.1 Definition of Pheromones 123
5.1.2 Classification of Pheromones 123
5.2 History of Pheromone Research 125
5.3 Research Techniques in Pheromone Science 127
5.3.1 The Collecting of Pheromones 127
5.3.2 Bioassay-Guided Purification 128
5.3.3 Structure Determination and Synthesis 128
5.3.4 Field Bioassay 129
5.3.5 Structure Elucidation of the Male-Produced Aggregation Pheromone of the Stink Bug Eysarcoris lewisi - A Case Study 129
5.4 Structural Diversity Among Pheromones 132
5.5 Complexity of Multicomponent Pheromones 137
5.6 Stereochemistry and Pheromone Activity 139
5.6.1 Only a Single Enantiomer is Bioactive and its Opposite Enantiomer Does Not Inhibit the Response to the Active Isomer 139
5.6.2 Only One Enantiomer is Bioactive, and its Opposite Enantiomer Inhibits the Response to the Pheromone 139
5.6.3 Only One Enantiomer is Bioactive, and its Diastereomer Inhibits the Response to the Pheromone 139
5.6.4 The Natural Pheromone is a Single Enantiomer, and its Opposite Enantiomer or Diastereomer is Also Active 140
5.6.5 The Natural Pheromone is a Mixture of Enantiomers or Diastereomers, and Both of the Enantiomers, or All of the Diastereomers are Separately Active 141
5.6.6 Different Enantiomers or Diastereomers are Employed by Different Species 141
5.6.7 Both Enantiomers are Necessary for Bioactivity 141
5.6.8 One Enantiomer is More Active Than the Other, but an Enantiomeric or Diastereomeric Mixture is More Active Than the Enantiomer Alone 141
5.6.9 One Enantiomer is Active on Males, While the Other is Active on Females 142
5.6.10 Only the meso-Isomer is Active 142
5.7 Pheromones With Kairomonal Activities 142
5.8 Mammalian Pheromones 143
5.9 Invention of Pheromone Mimics 145
5.10 Conclusion 147
Acknowledgements 147
References 147
6 Use of Volatiles in Pest Control 151
J. Richard M. Thacker and Margaret R. Train
6.1 Introduction 151
6.2 Repellents (DEET, Neem, Essential Oils) 151
6.3 Volatile Synthetic Chemicals and Fumigants 154
6.4 Pheromones 158
6.5 Volatile Allelochemicals 165
6.6 Plant Volatiles and Behavioural Modification of Beneficial Insects 166
6.7 Concluding Comments 167
References 168
7 Challenges in the Synthesis of Natural and Non-Natural Volatiles 173
Anthony A. Birkbeck
7.1 Introduction - The Art of Organic Synthesis 173
7.2 Overcoming Challenges in the Small-Scale Synthesis of Natural Volatile Compounds 174
7.2.1 D,L-Caryophyllene (1964) 174
7.2.2 b-Vetivone (1973) 175
7.3 Overcoming Challenges in the Large-Scale Synthesis of Nature Identical and Non-Natural Molecules 176
7.3.1 (Z)-3-Hexenol 176
7.3.2 Citral 177
7.3.3 (-)-Menthol 179
7.3.4 Habanolide 180
7.4 Remaining Challenges in the Large-Scale Synthesis of Natural and Non-Natural Volatiles 180
7.5 Design and Synthesis of Novel Odorants and Potential Industrial Routes to a Natural Product 182
7.5.1 Cassis (Blackcurrant) 182
7.5.2 Patchouli 184
7.5.3 Musk 187
7.5.4 Sandalwood 189
7.6 Other Challenges 193
7.7 Conclusion 193
Acknowledgements 194
Dedication 195
References 195
8 The Biosynthesis of Volatile Sulfur Flavour Compounds 203
Meriel G. Jones
8.1 Introduction: Flavours as Secondary Metabolites 203
8.2 Sulfur in Plant Biology 204
8.3 Sulfur Compounds as Flavour Volatiles 205
8.4 The Alk(en)yl Cysteine Sulfoxide Flavour Precursors 206
8.5 Biosynthesis of the Flavour Precursors of Allium 207
8.5.1 The Biosynthesis of Allium Flavour Precursors via g-Glutamyl Peptides 208
8.5.2 The Biosynthesis of Allium Flavour Precursors via Cysteine Synthases 209
8.6 Formation of Volatiles from CSOs 210
8.6.1 S-Methyl-L-cysteine sulfoxide 210
8.6.2 Release of the Allium CSOs 211
8.7 The Allium Flavour Volatiles 212
8.8 The Enzyme Alliinase 213
8.9 The Enzyme Lachrymatory Factor Synthase 214
8.10 The Biological Roles of the Flavour Precursors 215
8.11 The Glucosinolate Flavour Precursors 216
8.12 GS and Their Biosynthetic Pathways 216
8.13 Release of Volatile GS Hydrolysis Products 218
8.14 The Biological Role of Glucosinolates 220
8.15 Application of Transgenic Technology to Applied Aspects of GS Biosynthesis 222
8.16 Volatile Sulfur Compounds from Other Plants 222
8.16.1 Complex Organic Sulfur Volatiles 222
8.16.2 Simple Sulfur Volatiles 223
8.16.3 Hydrogen Sulfide 223
8.16.4 Methanethiol 224
8.17 Conclusion 224
References 224
9 Thermal Generation of Aroma-Active Volatiles in Food 231
Christoph Cerny
9.1 Introduction 231
9.2 The Maillard Reaction 233
9.2.1 The Amadori Rearrangement 234
9.2.2 Deoxyosones 235
9.2.3 Retro-Aldolization 235
9.3 Formation of Aroma Compounds in the Later Stages of the Maillard Reaction 237
9.3.1 2-Furfurylthiol 237
9.3.2 4-Hydroxy-2,5-dimethyl-3(2H)-furanone 239
9.3.3 Alkyl and Alkenylpyrazines 239
9.3.4 2-Acetyl-1-pyrroline 241
9.4 The Strecker Degradation 241
9.5 Caramelization 244
9.6 Thiamin Degradation 246
9.7 Ferulic Acid Degradation 246
9.8 Fat Oxidation 247
9.9 Conclusion 250
References 250
10 Human Olfactory Perception 253
Alan Gelperin
10.1 Introduction 253
10.2 Historical Perspective on Olfactory Perception 254
10.3 Human Olfactory Pathway 255
10.4 Functional Studies in Human Subjects 256
10.5 Functional Studies in Brain-Damaged Subjects 259
10.6 Single Odorants, Binary Mixtures and Complex Odour Objects 259
10.7 Olfactory Versus Trigeminal Odorant Identification 262
10.8 Orthonasal Versus Retronasal Odour Perception 263
10.9 Specific Anosmias 264
10.10 MHC-Correlated Odour Preferences in Human Subjects 265
10.11 Odour Deprivation and Odour Perception 266
10.12 Age-Related Decline in Olfactory Perception 267
10.13 New Neurons in Adult Brains 268
10.14 Epidemiological Studies of Human Olfaction 268
10.15 Active Sampling and Olfactory Perception 269
10.16 Human Olfactory Imagery 270
10.17 Top-Down Influences on Olfactory Perception 271
10.18 Reproductive State and Olfactory Sensitivity 272
10.19 Olfaction, Hunger and Satiety 273
10.20 Odour Perception Bias by Odour Names 274
10.21 Olfaction and Disease States 275
10.22 Prenatal and Postnatal Influences on Infant Odour/Flavour Preferences 276
10.23 Future Directions 277
Acknowledgements 277
References 278
11 Perfumery - The Wizardry of Volatile Molecules 291
Christophe Laudamiel
11.1 The Big Picture 291
11.2 Wizardry No. 1: Full Holograms Create Real Emotions 292
11.3 Volatiles Need a Language Wizard 296
11.4 Wizardry No. 2: The Perfumer in the Jungle of Volatiles to Create Emotions 298
11.5 Wizardry No. 3: End Results Are Music to the Nose 303
References 304
12 Microencapsulation Techniques for Food Flavour 307
Youngjae Byun, Young Teck Kim, Kashappa Goud H. Desai and Hyun Jin Park
12.1 Demands 307
12.2 Microencapsulation in the Food Industry 307
12.3 Techniques and Materials for Flavour Microencapsulation 308
12.3.1 Spray Drying 308
12.3.2 Extrusion 312
12.3.3 Cyclodextrin Inclusion Complexes 314
12.3.4 Helical Inclusion Complexes 316
12.3.5 Fluidized Bed Coating 318
12.3.6 Top Spray Fluidized Bed Coating 318
12.3.7 Bottom Spray System 318
12.3.8 Wurster System 320
12.3.9 Tangential Spray or Rotary Fluidized Bed Coating 320
12.3.10 Coacervation 320
12.3.11 Double or Multiple Emulsion with Freeze Drying 321
12.3.12 Co-Crystallization 322
12.3.13 Spray Chilling and Spray Cooling 322
12.3.14 Supercritical Fluids 323
12.3.15 Other Techniques 323
12.4 Conclusion and Future Trends 325
References 326
13 Profragrances and Properfumes 333
Andreas Herrmann
13.1 Introduction 333
13.2 Release of Alcohols 335
13.2.1 Enzymatic Hydrolysis 335
13.2.2 Neighbouring-Group-Assisted, Non-Enzymatic Hydrolysis 340
13.3 Release of Carbonyl Derivatives 346
13.3.1 Oxidations 346
13.3.2 Reversible Systems 350
13.3.3 Retro 1,4-Additions 354
13.4 Profragrance and Properfume Strategies 356
13.4.1 Performance and Cost Efficiency 356
13.4.2 Stability 357
13.5 Conclusion 357
Acknowledgements 358
References 358
14 Reactions of Biogenic Volatile Organic Compounds in the Atmosphere 363
Russell K. Monson
14.1 Introduction 363
14.2 The Relative Importance of Anthropogenic Versus Biogenic VOC Emissions to Atmospheric Chemistry 364
14.3 Overview of BVOC Oxidation 365
14.4 The Types of Emitted BVOCs and General Roles in Atmospheric Chemistry 370
14.5 Gas Phase Oxidation of BVOCs 372
14.6 Gas Phase Chemistry of BVOCs in Urban and Suburban Airsheds 374
14.7 Gas Phase Chemistry Within and Above Forests 375
14.8 BVOC Emissions and SOA Formation 377
14.9 Conclusion 381
References 381
Index 389
