Wine

Dr Jokie Bakker has worked as a university tutor and a wine industry consultant, and was formerly Principal Researcher in food flavour and colour at IFR Reading. Dr Ronald J. Clarke is a writer and food industry consultant based in Chichester, UK, and is co-editor of Coffee: Recent Developments.

“This book is a delight to read. It is well produced, contains a wealth of detailed and interesting information, and good use is made of figures and, especially, tables. The authors are clearly very enthusiastic about their subject and the book is so well-written one can open it anywhere, start reading, and be instantly captivated. This book is essential reading for any chemist interested in wine (and who is not?) or in flavour chemistry in general.”  (Chromatographia, 1 August 2013)

• Preface to the Second Edition xvPreface to the First Edition xvii1 Introduction 11.1 Scope of the book 11.2 Historical background 21.3 Wine flavour 31.4 Wine colour 61.5 Vinification 61.5.1 Vinification process 8Pre-fermentation 9Fermentation 15Post-fermentation 171.5.2 Red wines 22Pre-fermentation 22Fermentation 23Post-fermentation 241.5.3 White wines 25Pre-fermentation 26Fermentation 27Post-fermentation 281.5.4 Specialized wines 28Rosé wines 28Wines made from organically farmed grapes 29Wines with added resin 30Wines with low alcohol content 31Sweet wines 31Sparkling wine in Champagne 32Sparkling wine by other methods 33Wines by carbonic maceration 34Wines by thermovinification 34Wines matured Sur Lie 351.5.5 Fortified wines 35Port wine 36Sherry 38Madeira 401.6 Physiological effects 421.6.1 Attributed negative effects 431.6.2 Wine ethyl alcohol (ethanol) 431.6.3 Effects of phenols 45Resveratrol 46Bibliography 482 Grape Varieties and Growing Regions 532.1 Wine grapes 532.2 Vine plant characteristics 562.3 Soil, climate and ripeness 572.3.1 Soil 572.3.2 Climate 582.3.3 Ripeness 642.4 Grape growing regions of the world 652.4.1 World wine production 652.4.2 Regions 662.5 Chemical composition of grapes, must and finished wines 712.5.1 Grapes and must 712.5.2 Finished wine 792.6 Quality control and classification of wines 792.6.1 France 792.6.2 Germany 822.6.3 Italy 832.6.4 Spain 842.6.5 Australia 842.6.6 USA 852.6.7 Quality control systems in the European Union 86Bibliography 873 Basic Taste and Stimulant Components 893.1 Introduction 893.2 Basic taste perception 903.2.1 Role of taste 903.2.2 Taste perception mechanism 913.3 Ethyl alcohol 923.3.1 Measurement of ethyl alcohol content in wines 933.3.2 Measurement of sugar content in musts and wines 94Brix scale 94Baumé and Oeschele scales 96Prediction of alcohol content in the finished wine 963.3.3 Sugar content of grapes and must 973.3.4 Chaptalization 983.4 Acidity 993.4.1 Contents of organic acids 1003.4.2 Measurement of acid content 1043.4.3 Acid taste 1053.5 Sweetness 1093.5.1 Chemical structure of sugars 1093.5.2 Content/sweetness 1093.6 Bitterness, astringency and mouthfeel 1133.6.1 Basic chemistry 113Non-flavanoids 113Flavan-3-ols 114Flavonoids 116Anthocyanins 1173.6.2 Basic technology 118Location of polyphenols in grapes 118Use of the term ‘tannins’ and their classification 119Grape tannins 120Quantifying methods 121HPLC measurements 122Other methods 123Analyses in grapes and during wine-making 1243.6.3 Bitter constituents 127White wines 127Red wines 1273.6.4 Astringency 1273.6.5 Mouthfeel 1283.7 Colouring matter 1293.7.1 Colour of red wines 1293.7.2 Colour of white wines 1323.8 Other constituents 1343.8.1 Sulfur dioxide 134Basic chemistry 135Technical use 135Taste effects 1363.8.2 Carbon dioxide 136Formation and handling of CO 2 137Sensory factors 1373.8.3 Oxygen 138Basic chemistry 138Oxygen content in wines 139Effect of oxygen on wine 1413.9 Changes in maturation 1423.9.1 ‘In-barrel’ ageing 143Vats 143Extraction from barrels 144Oxidation in barrels 1453.9.2 ‘In-bottle’ ageing 1463.9.3 Oxidation–reduction (redox) potential 146General 147Nernst equation 147Redox potentials in wine 148Redox potentials during vinification 149Bibliography 1504 Volatile Components 1554.1 General 1554.1.1 Sensory perception 1564.1.2 Partition coefficients 1584.1.3 Threshold flavour/odour levels 161Units 163Consistency of threshold odour levels 164Threshold level difference between sniffing and tasting 164Threshold levels in solutions of dissolved substances in water and in beverages 166Relationship of threshold values to partition coefficients 168Volatile compound concentration in the vapour phase 1704.1.4 Flavour/odour descriptions 173Use of word descriptions 173Intensity of flavour/odour 1754.2 Volatile compounds detected in wines 1754.2.1 Types of aroma in volatile compounds 1784.2.2 Stereochemical effects in aroma volatile compounds 1804.3 Contents and sensory evaluation data 1804.3.1 Esters 180Structure 181Presence in wines 181Flavour characteristics 1824.3.2 Aldehydes 189Presence in wine 189Flavour characteristics 1904.3.3 Ketones 190Presence in wines 190Flavour characteristics 1904.3.4 Acetals 1964.3.5 Alcohols 197Presence in wines 197Flavour characteristics 2014.3.6 Lactones and furanones 201Molecular structures 201Presence in wines 205Flavour characteristics 2074.3.7 Acids 207Presence in wines 207Flavour characterisitcs 2084.3.8 Nitrogeneous compounds 2084.3.9 Phenols 209Presence in wines 209Flavour characteristics 2094.3.10 Terpenes 209Chemical structure 209Presence in grapes/wines 213Flavour characteristics 2154.3.11 Pyrazines 216Chemical structure 216Presence in grapes/wines 216Flavour characteristics 2164.3.12 Sulfur compounds 219Chemical structure 219Presence in wines 219Flavour characteristics 2204.4 Changes during maturation 2214.4.1 Fermentation and storage of wines ‘in-vat (tank)’ and ‘in-barrel (cask)’ 221Fermentation 221Storage 2224.4.2 ‘In-bottle’ ageing 224Changes in ester content 225Substances produced by carbohydrate degradation 225Sulfur compounds 225Changes in terpenoids 225Formation of substances from carotene breakdown 2264.5 Aroma detection and quantification 2274.5.1 Gas chromatography 2274.5.2 Sample preparation 2284.5.3 Olfactometry 2304.6 Chemical structure and physical properties 231Bibliography 2315 Wine Tasting Procedures and Overall Wine Flavour 2395.1 Wine tasting 2395.2 Wine tasting procedure 2415.2.1 Tasting glass 2415.2.2 Serving 2435.2.3 Visual 2435.2.4 Smell 2445.2.5 Flavour 2465.2.6 Interactions 2475.2.7 Astringency 2485.2.8 Judging the wine 2495.2.9 Reasons for wine tasting 250Sensory analysis 250Quality tastings 251Identifying wines by tasting 251Sensory analyses used in research 252Consumer tasting 252Analytical tasting 2535.2.10 Wine tasting information and analysis 254Statistical analysis 2545.3 Factors influencing sensory perception 2565.3.1 Threshold and sensitivity 2575.3.2 Vocabulary 2585.4 Balance of taste sensations in wine 2585.5 Wine aromas 2595.5.1 Odour/aroma classification 2615.5.2 Aroma/odour characteristics of wines from particular grape varieties 2625.5.3 Variants in Cabernet Sauvignon wine flavour 2705.5.4 Variants of Chardonnay wine flavour 2715.5.5 Flavour description of some other commercial wines 2735.5.6 Off-odours and taints 274Cork taint 275Mousiness 278Ethylphenols 2795.6 Wine and food flavour 2795.7 Aroma indices and statistical methods 2825.7.1 Flavour unit concept 2825.7.2 Odour activity unit 2845.7.3 Multivariate and other statistical procedures 285Bibliography 2886 Sherry, Port and Madeira 2916.1 Introduction 2916.1.1 Sherry introduction 2916.1.2 Port introduction 2926.1.3 Madeira introduction 2926.1.4 Comparisons between fortified wines 2936.1.5 Ethyl alcohol – sensory effect 2946.1.6 Ethyl alcohol – chemical effect 2956.1.7 Sweetness 2956.2 Sherry 2956.2.1 Wine producers 2966.2.2 Commercial wine styles 2966.2.3 Wine writers’ comments 2976.2.4 Grapes and must 2976.2.5 Base wine 2986.2.6 Maturation 2996.2.7 Maturation changes under flor 2996.2.8 Maturation changes without flor 3016.2.9 Maturation with and without flor 3026.2.10 Volatile compounds 3026.2.11 Changes during maturation in phenolic compound content 3096.3 Port wine 3116.3.1 Port wine producers 3116.3.2 Commercial Port wine styles 3126.3.3 Wine writers’ comments 3136.3.4 Grapes and must 3146.3.5 Fermentation and base Port wine 3156.3.6 Port wine compared to red table wine 3176.3.7 Maturation 3186.3.8 Colour changes during maturation 3186.3.9 Volatile changes during maturation 3226.4 Madeira 3276.4.1 Madeira wine producers 3276.4.2 Commercial Madeira wine styles 3276.4.3 Wine writers’ comments 3286.4.4 Sensory properties 3286.4.5 Grapes and must 3286.4.6 Base wines maturation 3296.4.7 Volatile compounds 330Bibliography 3357 Formation Pathways in Vinification 3417.1 Introduction 3417.2 Process variables in vinification 3427.2.1 Grapes 3427.2.2 Yeast strain 3447.2.3 Malo-lactic organisms 3477.2.4 Temperature 347Standard operating temperature 347Thermovinification 3487.2.5 Clarification procedures 3497.2.6 Nutrient medium in fermentation 3497.2.7 Maceration 3517.3 Production of ethyl alcohol 3517.4 Production of individual groups of compounds 3527.4.1 Esters 3527.4.2 Aldehydes 3537.4.3 Ketones 3547.4.4 Acetals 3547.4.5 Higher alcohols 3557.4.6 Furanones and lactones 3567.4.7 Acids 3577.4.8 Amines 3577.4.9 Phenols (volatile) 3577.4.10 Terpenes 3597.4.11 Pyrazines 3607.4.12 Sulfur compounds 3607.5 Noble Rot 362Bibliography 364Appendix I 367I. 1 Chemical formulae nomenclature 367I.. 1 Nomenclature for a homologous series of compounds (Greek number/word system) 367I.1. 2 System for substituent groups (derivatives) 368I.1. 3 System for substituting in long-chain compounds 368I.1. 4 System for characterizing esters 368I.1. 5 System for characterizing unsaturated compounds 369I.1. 6 Systems for esters, thiols and thio-compounds 369I.1. 7 Miscellaneous IUPAC recommendations 369I.1. 8 Alternative chemical names 369I.1. 9 Numbering systems for ring compounds 370I.1.10 Trivial and common names for derivative alkanes and other compounds 370I.1. 11 General 371I. 2 Stereochemistry 371I.2. 1 Enantiomers 371Optical activity 372Chirality 373Occurrence of enantiomers 375I.. 2 Geometrical (stereo-) isomers 375I.2. 3 Tautomerism 376I. 3 Chemistry of the oxidation of organic compounds 377I.3. 1 Auto- and enzymatic oxidation of lipids 378I.3. 2 Oxidation–reduction of alkyl alcohols and aldehydes 379I.. 3 Oxidation of phenolic compounds 380Oxidation of procyanidins 383Oxidation of non-flavanoid phenolic compounds 383General 384I.3.4 Oxidation–reduction (redox) potentials 384I. 4 Estimation of partition coefficients of volatile compounds in air/water 386I. 5 Grape varieties and cultivars 389Appendix II 395II. 1 Units 395II.2 Data sources 395Tables of molecular formulae, weight and physical properties for each group of volatile compounds found in wine –Volatile esters 396–Volatile aldehydes 399–Volatile ketones 400–Volatile alcohols 401–Volatile furanones/lactones 402–Volatile acids 403–Volatile phenols 404–Volatile terpenes 404–Volatile methoxy pyrazines 405–Volatile sulfur compounds 405Index 407