Chemistry and Technology of Flavours and Fragrances

Modern flavours and fragrances are complex formulated products, containing blends of aroma compounds with auxiliary materials, enabling desirable flavours or fragrances to be added to a huge range of products. From the identification and synthesis of materials such as cinnamaldehyde and vanillin in the 19th Century to the current application of advanced analytical techniques for identification of trace aroma compounds present in natural materials, the flavour and fragrance industry has developed as a key part of the worldwide specialty chemicals industry.
With contributions mainly coming from industry based experts, Chemistry & Technology of Flavours and Fragrances provides a detailed overview of the synthesis, chemistry and application technology of the major classes aroma compounds. With separate chapters covering important technical aspects such as the stability of aroma compounds, structure – odour relationships and identification of aroma compounds, this book will be essential reading for both experienced and graduate level entrants to the flavour & fragrance industry. It will also serve as an important introduction to the subject for chemists and technologists in those industries that use flavours and fragrances, eg food, cosmetics & toiletries, and household products.

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INTRODUCTION.
David J Rowe.
History.
The Classical World.
The Mediaeval World.
From the Renaissance to the Enlightment.
The Industrial Age.
The Post–War World.
Technical factors:.
Social factors.
The Future.
The Structure of the Flavour and Fragrance Industry.
A Note on Regulations.
A Note on Quality.
IDENTIFICATION OF AROMA CHEMICALS.
Neil C. Da Costa and Sanja Eri.
Introduction.
Isolation of Aroma Chemicals.
Solvent Extraction.
Extraction of liquid samples.
Extraction of solid samples.
Soxhlet Extraction.
Accelerated Solvent Extraction (ASE).
S upercritical Fluid Extraction (SFE).
Fractionation of solvent extracts.
Concentration of solvent extracts.
Solvent Assisted Flavor Evaporation (SAFE).
Steam Distillation Methods.
Headspace Techniques.
Static Headspace.
Dynamic Headspace.
Direct Thermal Desorption (DTD).
Sorptive techniques.
Solid Phase Microextraction (SPME).
Headspace sorptive extraction (HSSE) and stir bar sorptive extraction (SBSE) (commercially available as TwisterTM).
Gas Chromatography–Olfactometry (GC–O).
Techniques for identification of aroma compounds.
A Case Study: Generessenceâ.
Sample Preparation.
Valencia Orange.
Roast Chicken.
Narcissus.
Post–Analysis Work.
References.
FLAVOUR GENERATION IN FOOD.
Liam O’Hare and John Grigor.
Introduction.
Taste and Aroma.
Cooked Meat.
Flavour Precursors.
Lipid Oxidation and Degradation.
Hydrolysis.
Oxidation.
Fatty Aldehydes as flavour compounds.
Fatty Aldehydes (pentanal and hexanal) as flavour precursors.
Other lipid derived flavour precursors.
Fatty Aldehydes as "Flavour Moderators".
Strecker Degradation.
The Maillard Reaction.
Caramelisation.
Influence of Method of Cooking.
Roasting Frying and Grilling.
Pyrazines.
Thiazoles.
Thiophenes and Furans.
Boiling.
Reheating.
Species Differences.
Fermented Foods.
Cheese.
Lactose and citrate fermentation.
Protein Degradation.
Proteolysis.
Metabolism of free amino acids.
Cysteine and Methionine.
Threonine.
Arginine.
Valine, Leucine and Isoleucine.
Phenylalanine and Tyrosine.
Tryptophan.
Lipid Degradation.
Oxidative degradation.
Hydrolytic Degradation.
Acids.
Esters.
Thioesters.
Methyl Ketones and Secondary Alcohols.
Lactones.
Acknowledgments.
References.
AROMA CHEMICALS I: C,H,O COMPOUNDS.
David J. Rowe.
Introduction.
Alcohols.
Saturated Alkyl alcohols.
Unsaturated al kyl alcohols.
Complex Fragrance Alcohols.
Aromatic and aralkyl alcohols.
Phenolics.
Acids.
Saturated aliphatic acids.
Unsaturated acids.
Aromatic acids.
Esters.
Saturated.
Unsaturated.
Aromatic esters.
Lactones – gamma and delta.
Synthesis of esters.
Aldehydes.
Aliphatic.
Unsaturated.
Acetals.
Aromatics.
Nitriles.
Ketones.
“Carotenoids”; Ionones, Irones, Damascones and related compounds.
Hydrocarbons.
Acknowledgements.
References.
AROMA CHEMICALS II – HETEROCYCLES.
Michael Zviely.
Introduction.
Introduction to Heterocyclic Compounds.
Terminology of Heterocycles.
Non–aromatic Heterocyclic Compounds.
Oxygen Containing Heterocyclic Aroma Chemicals.
Oxiranes.
Furans and Hydrofurans.
Pyrans.
Oxepins.
Heterocyclic Compounds Containing Nitrogen and/or Sulphur.
Non–Aromatic Molecules.
Aromatic Molecules.
Thiophene Derivatives.
Pyrrole and Indole Derivatives.
Pyridine and Quinoline Derivatives.
Pyrazine and Quinoxaline Derivatives.
Thiazole Derivatives.
The Formation of Heterocyclic Compounds in Food.
References and Notes.
AROMA CHEMICALS III: SULPHUR COMPOUNDS.
Simon B. Jameson.
Thiols and Thioesters.
Acyclic Sulphides and Polysulphides.
Saturated Heterocyclic Sulphur Compounds.
Quality and Stability.
Acknowledgement.
References.
AROMA CHEMICALS IV: MUSKS.
Philip Kraft,.
.
Introduction.
Natural Musks.
Nitro Musks.
Pcm – Polycyclic Aromatic Musks.
Evolution Of The Industrial Synthesis Of Macrocycles.
Modern Macrocyclic Musks.
New Musk Structures.
Acknowledgement.
References.
AROMA CHEMICALS V: NATURAL AROMA CHEMICALS.
John Margetts.
Introduction.
The natural concept.
Chirality.
Isolation from natural sources such as essential oils.
Biotechnology.
Total Flavour Enhancement.
Individual Flavour Chemicals.
Alcohols.
Carbonyls.
Acids.
Lactones.
Esters.
Green Notes.
Pyrazines.
Sulphur Compounds.
Terpenoid and related Compounds.
Vanillin.
Precursors.
Soft Chemistry.
Conclusion.
References.
MOLECULES OF TASTE AND SENSATION.
Mark L. Dewis,.
Introduction.
The Trigeminal Nerve System, Taste and Oral Receptors.
The Trigeminal Nerve.
Gustation.
Oral Receptors.
Chemesthesis.
“Sensates”; Compounds which provide a sensory effect.
Tingle compounds.
Cooling compounds.
Pungent, warming and hot irritants.
Astringency.
Synergies.
Closing comments on Compounds which provide a sensory effect.
Taste active compounds.
Sweeteners.
Salt and enhancers.
Sour agents.
Bitter agents.
Umami ‘the fifth taste quality’.
Conclusions.
References.
STABILITY OF AROMA CHEMICALS.
Chris Winkel.
Introduction.
Flavour Stability.
Flavour Precursors.
Encapsulation.
Analogues.
Case Study 1: Citral And Vanillin Stability In Milk–Based Products.
Case Study 2: Stability Of Thiols In An Aqueous Process Flavouring.
Stability And Fragrance Applications.
Conclusion.
References.
RATIONAL ODORANT DESIGN.
Luca Turin.
Introduction.
Theories of olfaction.
For Shape:.
Plausibility.
The nature of the receptors.
Against Shape:.
No predictive ability.
Isosteric molecules smell different.
"Strong" shape looks unlikely.
"Weak" shape appears untestable.
The chiral receptor problem.
No odorant antagonists have been found.
We smell functional groups.
.
For Vibration.
Functional group recognition.
isosteric molecules accounted for.
Isotopes smell different (maybe).
Enantiomers accounted for (differently).
The Chiral Limit.
Against vibration.
Mechanism novel and unproven.
Inability to account for odorant intensity.
Rational design by shape.
Rational design by vibration.
Replacement molecu