Chemistry and Biology of Volatiles

Dr. Andreas Herrmann is a research chemist at Firmenich SA, an international flavour and fragrance company, in Genève (Switzerland), working on the development of new fragrance delivery systems. He has published a series of research papers on the chemical release of volatiles under mild reaction conditions. He is the author or co-author of about 30 scientific publications and 10 international patent applications.

"Coming to a conclusion, this wonderful, informative and very interesting book presents an excellent overview of small volatile organic compounds and their role in our life and environment. Really fascinating is the entirety of scientific disciplines which were addressed by this book." (Flavour and Fragrance Journal, 2011) "In spite of its few shortcomings, this book deserves to be a well-used reference in the library of any laboratory specialising in VOC". (Chemistry World, 1 May 2011)"The Chemistry and Biology of Volatiles takes an interdisciplinary approach to volatile molecules". (Small Business VoIP, 14 December 2010)

• Foreword xiiiList of Contributors xvAcknowledgements xviiAbbreviations xix1 Volatiles – An Interdisciplinary Approach 1Andreas Herrmann1.1 Introduction 11.2 Geraniol – A Typical Example 21.3 Conclusion 8References 82 Biosynthesis and Emission of Isoprene, Methylbutanol and Other Volatile Plant Isoprenoids 11Hartmut K. Lichtenthaler2.1 Introduction 112.2 Plant Isoprenoids 122.3 Two IPP-Yielding Pathways in Plants 152.4 Prenyl Chain Formation and Elongation 162.5 Compartmentation of Plant Isoprenoid Biosynthesis 162.6 The Enzyme Steps of the Plastidic DOXP/MEP Pathway of IPP Formation 172.7 Cross-Talk Between the Two IPP Biosynthesis Pathways 192.8 Biosynthesis and Emission of Volatile Isoprene at High Irradiance 222.8.1 Regulation of Isoprene Emission 252.9 Inhibition of Isoprene Biosynthesis 262.9.1 Fosmidomycin and 5-Ketoclomazone 262.9.2 Diuron 272.10 Inhibition of Carotenoid and Chlorophyll Biosynthesis by Fosmidomycin and 5-Ketoclomazone 272.11 Biosynthesis and Emission of Methylbutenol at High Irradiance 282.12 Source of Pyruvate for Isoprene and Methylbutenol Biosynthesis 292.13 Branching Point of DOXP/MEP Pathway with Other Metabolic Chloroplast Pathways 302.14 Is There a Physiological Function of Isoprene and MBO Emission? 312.15 Biosynthesis and Emission of Monoterpenes, Sesquiterpenes and Diterpenes 332.15.1 Monoterpenes 352.15.2 Diterpenes 362.15.3 Sesquiterpenes 362.16 Some General Remarks on the Regulation of Terpene Biosynthesis in Plants 362.17 Volatile Terpenoids as Aroma Compounds of Wine 372.18 Function of Terpenes in Plant Defence 382.19 Conclusion 38Acknowledgements 39References 403 Analysis of the Plant Volatile Fraction 49Patrizia Rubiolo, Barbara Sgorbini, Erica Liberto, Chiara Cordero and Carlo Bicchi3.1 Introduction 493.2 Sample Preparation 503.2.1 ‘Liquid’ Phase Sampling 513.2.2 Headspace Sampling 513.2.3 Headspace–Solid Phase Microextraction 523.2.4 In-Tube Sorptive Extraction 543.2.5 Headspace Sorptive Extraction 553.2.6 Static and Trapped Headspace 563.2.7 Solid-Phase Aroma Concentrate Extraction 563.2.8 Headspace Liquid-Phase Microextraction 563.2.9 Large Surface Area High Concentration Capacity Headspace Sampling 593.3 Analysis 593.3.1 Fast-GC and Fast-GC-qMS EO Analysis 613.3.2 Qualitative Analysis 653.3.3 Quantitative Analysis 663.3.4 Enantioselective GC 703.3.5 Multidimensional GC Techniques 753.4 Further Developments 763.5 Conclusion 85Acknowledgements 87References 874 Plant Volatile Signalling: Multitrophic Interactions in the Headspace 95Andre Kessler and Kimberly Morrell4.1 Introduction 954.2 The Specificity and Complexity of Herbivore-Induced VOC Production 974.2.1 Plant Endogenous Wound Signalling 994.2.2 Herbivore-Derived Elicitors of VOC Emission 1024.3 Ecological Consequences of VOC Emission 1044.3.1 Within-Plant Defence Signalling 1044.3.2 Herbivore-Induced VOC Emission as Part of a Metabolic Reconfiguration of the Plant 1054.3.3 Herbivores Use VOCs to Select Host Plants 1074.3.4 VOCs as Indirect Defences Against Herbivores 1084.3.5 VOCs in Plant–Plant Interactions 1114.4 Conclusion 112Acknowledgements 114References 1145 Pheromones in Chemical Communication 123Kenji Mori5.1 Introduction 1235.1.1 Definition of Pheromones 1235.1.2 Classification of Pheromones 1235.2 History of Pheromone Research 1255.3 Research Techniques in Pheromone Science 1275.3.1 The Collecting of Pheromones 1275.3.2 Bioassay-Guided Purification 1285.3.3 Structure Determination and Synthesis 1285.3.4 Field Bioassay 1295.3.5 Structure Elucidation of the Male-Produced Aggregation Pheromone of the Stink Bug Eysarcoris lewisi – A Case Study 1295.4 Structural Diversity Among Pheromones 1325.5 Complexity of Multicomponent Pheromones 1375.6 Stereochemistry and Pheromone Activity 1395.6.1 Only a Single Enantiomer is Bioactive and its Opposite Enantiomer Does Not Inhibit the Response to the Active Isomer 1395.6.2 Only One Enantiomer is Bioactive, and its Opposite Enantiomer Inhibits the Response to the Pheromone 1395.6.3 Only One Enantiomer is Bioactive, and its Diastereomer Inhibits the Response to the Pheromone 1395.6.4 The Natural Pheromone is a Single Enantiomer, and its Opposite Enantiomer or Diastereomer is Also Active 1405.6.5 The Natural Pheromone is a Mixture of Enantiomers or Diastereomers, and Both of the Enantiomers, or All of the Diastereomers are Separately Active 1415.6.6 Different Enantiomers or Diastereomers are Employed by Different Species 1415.6.7 Both Enantiomers are Necessary for Bioactivity 1415.6.8 One Enantiomer is More Active Than the Other, but an Enantiomeric or Diastereomeric Mixture is More Active Than the Enantiomer Alone 1415.6.9 One Enantiomer is Active on Males, While the Other is Active on Females 1425.6.10 Only the meso-Isomer is Active 1425.7 Pheromones With Kairomonal Activities 1425.8 Mammalian Pheromones 1435.9 Invention of Pheromone Mimics 1455.10 Conclusion 147Acknowledgements 147References 1476 Use of Volatiles in Pest Control 151J. Richard M. Thacker and Margaret R. Train6.1 Introduction 1516.2 Repellents (DEET, Neem, Essential Oils) 1516.3 Volatile Synthetic Chemicals and Fumigants 1546.4 Pheromones 1586.5 Volatile Allelochemicals 1656.6 Plant Volatiles and Behavioural Modification of Beneficial Insects 1666.7 Concluding Comments 167References 1687 Challenges in the Synthesis of Natural and Non-Natural Volatiles 173Anthony A. Birkbeck7.1 Introduction – The Art of Organic Synthesis 1737.2 Overcoming Challenges in the Small-Scale Synthesis of Natural Volatile Compounds 1747.2.1 D,L-Caryophyllene (1964) 1747.2.2 b-Vetivone (1973) 1757.3 Overcoming Challenges in the Large-Scale Synthesis of Nature Identical and Non-Natural Molecules 1767.3.1 (Z)-3-Hexenol 1767.3.2 Citral 1777.3.3 (–)-Menthol 1797.3.4 Habanolide 1807.4 Remaining Challenges in the Large-Scale Synthesis of Natural and Non-Natural Volatiles 1807.5 Design and Synthesis of Novel Odorants and Potential Industrial Routes to a Natural Product 1827.5.1 Cassis (Blackcurrant) 1827.5.2 Patchouli 1847.5.3 Musk 1877.5.4 Sandalwood 1897.6 Other Challenges 1937.7 Conclusion 193Acknowledgements 194Dedication 195References 1958 The Biosynthesis of Volatile Sulfur Flavour Compounds 203Meriel G. Jones8.1 Introduction: Flavours as Secondary Metabolites 2038.2 Sulfur in Plant Biology 2048.3 Sulfur Compounds as Flavour Volatiles 2058.4 The Alk(en)yl Cysteine Sulfoxide Flavour Precursors 2068.5 Biosynthesis of the Flavour Precursors of Allium 2078.5.1 The Biosynthesis of Allium Flavour Precursors via g-Glutamyl Peptides 2088.5.2 The Biosynthesis of Allium Flavour Precursors via Cysteine Synthases 2098.6 Formation of Volatiles from CSOs 2108.6.1 S-Methyl-L-cysteine sulfoxide 2108.6.2 Release of the Allium CSOs 2118.7 The Allium Flavour Volatiles 2128.8 The Enzyme Alliinase 2138.9 The Enzyme Lachrymatory Factor Synthase 2148.10 The Biological Roles of the Flavour Precursors 2158.11 The Glucosinolate Flavour Precursors 2168.12 GS and Their Biosynthetic Pathways 2168.13 Release of Volatile GS Hydrolysis Products 2188.14 The Biological Role of Glucosinolates 2208.15 Application of Transgenic Technology to Applied Aspects of GS Biosynthesis 2228.16 Volatile Sulfur Compounds from Other Plants 2228.16.1 Complex Organic Sulfur Volatiles 2228.16.2 Simple Sulfur Volatiles 2238.16.3 Hydrogen Sulfide 2238.16.4 Methanethiol 2248.17 Conclusion 224References 2249 Thermal Generation of Aroma-Active Volatiles in Food 231Christoph Cerny9.1 Introduction 2319.2 The Maillard Reaction 2339.2.1 The Amadori Rearrangement 2349.2.2 Deoxyosones 2359.2.3 Retro-Aldolization 2359.3 Formation of Aroma Compounds in the Later Stages of the Maillard Reaction 2379.3.1 2-Furfurylthiol 2379.3.2 4-Hydroxy-2,5-dimethyl-3(2H)-furanone 2399.3.3 Alkyl and Alkenylpyrazines 2399.3.4 2-Acetyl-1-pyrroline 2419.4 The Strecker Degradation 2419.5 Caramelization 2449.6 Thiamin Degradation 2469.7 Ferulic Acid Degradation 2469.8 Fat Oxidation 2479.9 Conclusion 250References 25010 Human Olfactory Perception 253Alan Gelperin10.1 Introduction 25310.2 Historical Perspective on Olfactory Perception 25410.3 Human Olfactory Pathway 25510.4 Functional Studies in Human Subjects 25610.5 Functional Studies in Brain-Damaged Subjects 25910.6 Single Odorants, Binary Mixtures and Complex Odour Objects 25910.7 Olfactory Versus Trigeminal Odorant Identification 26210.8 Orthonasal Versus Retronasal Odour Perception 26310.9 Specific Anosmias 26410.10 MHC-Correlated Odour Preferences in Human Subjects 26510.11 Odour Deprivation and Odour Perception 26610.12 Age-Related Decline in Olfactory Perception 26710.13 New Neurons in Adult Brains 26810.14 Epidemiological Studies of Human Olfaction 26810.15 Active Sampling and Olfactory Perception 26910.16 Human Olfactory Imagery 27010.17 Top-Down Influences on Olfactory Perception 27110.18 Reproductive State and Olfactory Sensitivity 27210.19 Olfaction, Hunger and Satiety 27310.20 Odour Perception Bias by Odour Names 27410.21 Olfaction and Disease States 27510.22 Prenatal and Postnatal Influences on Infant Odour/Flavour Preferences 27610.23 Future Directions 277Acknowledgements 277References 27811 Perfumery – The Wizardry of Volatile Molecules 291Christophe Laudamiel11.1 The Big Picture 29111.2 Wizardry No. 1: Full Holograms Create Real Emotions 29211.3 Volatiles Need a Language Wizard 29611.4 Wizardry No. 2: The Perfumer in the Jungle of Volatiles to Create Emotions 29811.5 Wizardry No. 3: End Results Are Music to the Nose 303References 30412 Microencapsulation Techniques for Food Flavour 307Youngjae Byun, Young Teck Kim, Kashappa Goud H. Desai and Hyun Jin Park12.1 Demands 30712.2 Microencapsulation in the Food Industry 30712.3 Techniques and Materials for Flavour Microencapsulation 30812.3.1 Spray Drying 30812.3.2 Extrusion 31212.3.3 Cyclodextrin Inclusion Complexes 31412.3.4 Helical Inclusion Complexes 31612.3.5 Fluidized Bed Coating 31812.3.6 Top Spray Fluidized Bed Coating 31812.3.7 Bottom Spray System 31812.3.8 Wurster System 32012.3.9 Tangential Spray or Rotary Fluidized Bed Coating 32012.3.10 Coacervation 32012.3.11 Double or Multiple Emulsion with Freeze Drying 32112.3.12 Co-Crystallization 32212.3.13 Spray Chilling and Spray Cooling 32212.3.14 Supercritical Fluids 32312.3.15 Other Techniques 32312.4 Conclusion and Future Trends 325References 32613 Profragrances and Properfumes 333Andreas Herrmann13.1 Introduction 33313.2 Release of Alcohols 33513.2.1 Enzymatic Hydrolysis 33513.2.2 Neighbouring-Group-Assisted, Non-Enzymatic Hydrolysis 34013.3 Release of Carbonyl Derivatives 34613.3.1 Oxidations 34613.3.2 Reversible Systems 35013.3.3 Retro 1,4-Additions 35413.4 Profragrance and Properfume Strategies 35613.4.1 Performance and Cost Efficiency 35613.4.2 Stability 35713.5 Conclusion 357Acknowledgements 358References 35814 Reactions of Biogenic Volatile Organic Compounds in the Atmosphere 363Russell K. Monson14.1 Introduction 36314.2 The Relative Importance of Anthropogenic Versus Biogenic VOC Emissions to Atmospheric Chemistry 36414.3 Overview of BVOC Oxidation 36514.4 The Types of Emitted BVOCs and General Roles in Atmospheric Chemistry 37014.5 Gas Phase Oxidation of BVOCs 37214.6 Gas Phase Chemistry of BVOCs in Urban and Suburban Airsheds 37414.7 Gas Phase Chemistry Within and Above Forests 37514.8 BVOC Emissions and SOA Formation 37714.9 Conclusion 381References 381Index 389