Aroma biotechnology opens access to natural volatile flavors. Due to the attribute of "naturalness" these aromas are the most valuable ingredients for foods, cosmetics and related products. Due to problems of supply from agricultural sources, legal restrictions and numerous advances in cell biochemistry and bioengineering the manufacturing of aromas and flavors using bioprocesses has developed dramatically during the last decade. The author describes biocatalyzed and biogenetic routes leading to aromas and flavor compounds and he depicts in detail their utilisation in industrial scale processes. All the important topics, including de-novo-synthesis, genetic engineering, in vitro rDNA methods, laboratory requirements and techniques, upscaling, product recovery, profitability, and legal aspects are covered. R.G. Berger contributes his own experimental experience to all except one chapter and leads the reader into state-of-the-art aroma biotechnology.

1 Aroma Compounds in Food.- 1.1 Aroma, Flavor, and Fragrance Compounds.- 1.2 Character Impact Components.- 1.3 Categories of Aromas.- 1.4 Functions of Aromas.- 1.5 Bioactivity of Aromas.- 2 The Roots: Empirical Food Biotechnologies and Formation of Aroma Compounds.- 2.1 Characterization of Yeasts.- 2.2 Aroma Development in Beer.- 2.3 Aroma Development in Wine.- 2.3.1 Yeast and Wine Aroma.- 2.3.2 Yeast Enzymes.- 2.3.3 Noble Rot Infected Grape IB.- 2.3.4 Malolactic Fermentation.- 2.3.5 Technological Developments.- 2.4 Yeast Cells As a Source of Aroma.- 2.5 Aromas of Fermented Milk.- 2.6 Bakery Products.- 2.7 Nondairy Acidic Fermentations.- 2.8 Fermented Plant Materials.- 2.9 Ethnic Food.- 2.9.1 Koji and Derivatives.- 2.9.2 Sake.- 2.9.3 Miscellaneous Fermented Food.- 2.10 Aroma Enhancement by Mixed Cultures.- 2.11 Conclusions.- 3 Why Novel Biotechnology of Aromas?.- 3.1 Aromas from Living Cells.- 3.2 The Legal Situation.- 3.3 The Potential of Biocatalysts.- 4 Laboratory Requirements and Techniques.- 4.1 Laboratory Equipment.- 4.2 The Biological Materials.- 4.3 Laboratory-Scale Cultivation.- 4.4 Nutrient Media.- 4.5 Analysis of Nonvolatiles.- 4.6 Analysis of Volatile Bioflavors.- 4.6.1 Chirospecific Gas Chromatography.- 4.6.2 Stable Isotope Analysis: IRMS and SNIF-NMR.- 5 Aroma Compounds from Microbial De Novo Synthesis.- 5.1 A Short History of Bioflavors.- 5.2 Oligo - Isoprenoids.- 5.3 Aliphatics.- 5.3.1 Carboxylic Acids.- 5.3.2 Lipoxygenase and Cyclooxygenase Products.- 5.3.3 Carbonyls.- 5.3.4 Alkanols.- 5.3.5 Esters.- 5.4 Aromatics.- 5.4.1 Vanillin.- 5.4.2 Cinnamates.- 5.4.3 Heterocycles.- 5.5 Degradation of Off-Odor.- 5.6 Are Microbial Volatiles Secondary Metabolites?.- 6 Biotransformation/Bioconversion.- 6.1 Monoterpenes.- 6.2 Sesquiterpenes.- 6.3 Fatty Acid Derivatives.- 6.4 Aromatics and Heterocycles.- 7 Enzyme Technology.- 7.1 Lipases.- 7.1.1 Lipolysis.- 7.1.2 Kinetic Resolution of Racemates.- 7.1.3 Reverse Hydrolysis.- 7.1.4 Nonaqueous Reaction Media.- 7.1.5 Immobilization.- 7.2 Carbohydrases.- 7.2.1 Glycosidic Aroma Precursors.- 7.2.2 Other Glycanases.- 7.3 Proteases.- 7.4 Oxidoreductases.- 7.5 Miscellaneous Enzymes.- 7.6 Cofactor Recycling.- 8 Genetically Altered Catalysts.- 8.1 Mutants and Fusants.- 8.2 In Vitro rDNA Technique.- 8.2.1 Enzymes.- 8.2.2 Lactococci HO.- 8.2.3 Yeasts.- 8.2.4 Higher Fungi.- 8.2.5 Non-Food Species.- 9 Plant Catalysts.- 9.1 Plant Enzymes.- 9.1.1 Lipoxygenase Derived Aromas.- 9.2 Precursor Atmosphere Stored Fruits.- 9.3 In Vitro Plant Cell Culture.- 9.3.1 De Novo Syntheses.- 9.3.2 Differentiated Cells.- 9.3.3 Conversion and Conjugation Of Substrates.- 9.3.4 Key Parameters for the Production Of Aromas.- 9.3.5 Phototrophic in Vitro Cells.- 9.3.6 Plant Genetic Engineering.- 9.3.7 Scaling-Up Experiments.- 10 Bioprocess Technology.- 10.1 Bioreactor Design.- 10.1.1 Mode of Operation.- 10.1.2 Fluidized Bed Reactor.- 10.1.3 Application of Membranes.- 10.1.4 Solid State Reactor.- 10.1.5 Alternative Reactors.- 10.2 Process Monitoring.- 10.3 Downstreaming Volatile Flavors.- 10.3.1 Degradation of Volatiles.- 10.3.2 Inhibition Phenomena.- 10.3.3 Solid/Liquid Separation.- 10.3.4 Electrodialysis.- 10.3.5 Reactive Extraction.- 10.3.6 Two Phase Extraction.- 10.3.7 Solid Phase Extraction.- 10.3.8 Gas Extraction.- 10.3.9 Membranes.- 11 Toward an Industrial Application.- 11.1 Rapid Process Improvement.- 11.1.1 Improved Biotransformation.- 11.1.2 Improved De Novo Synthesis.- 11.2 Scaling-Up.- 11.3 Profitability Aspects.- 11.4 Present Industrial Applications.- 12 Outlook.- References.