Handbook of Enology, Volume 2

Foreword xi Preface to the Second Edition xiii Preface to the First Edition xv Remarks Concerning the Expression of Certain Parameters of Must and Wine Composition xix Part I – Chemistry of Wine 1 1 Organic Acids in Wine 3 1.1Introduction 3 1.2The Main Organic Acids 3 1.3Different Types of Acidity 8 1.4The Concept of pH and Its Applications 10 1.5Tartrate Precipitation Mechanism and Predicting Its Effects 24 1.6Tests for Predicting Wine Stability 32 1.7Preventing Tartrate Precipitation 41 References 55 2 Alcohols and Other Volatile Compounds 57 2.1Ethanol 57 2.2Other Simple Alcohols 59 2.3Polyols 62 2.4Aliphatic Fatty Acids 65 2.5Esters 66 2.6Miscellaneous Compounds 71 References 74 3 Carbohydrates 75 3.1Introduction 75 3.2Glucose and Fructose 76 3.3Other Sugars 79 3.4Chemical Properties of Sugars 82 3.5Sugar Derivatives 85 3.6Pectic Substances in Grapes 87 3.7Exocellular Polysaccharides from Microorganisms 95 References 101 4 Dry Extract and Minerals 105 4.1Introduction 105 4.2Dry Extract 106 4.3Ash 108 4.4Inorganic Anions 109 4.5Inorganic Cations 109 4.6Iron and the Iron Casse Mechanism 111 4.7Copper and Copper Casse 117 4.8Heavy Metals 121 References 125 5 Nitrogen Compounds 127 5.1Introduction 127 5.2The Various Forms of Nitrogen 127 5.3Amino Acids 130 5.4Other Forms of Nitrogen 136 5.5Proteins and Protein Haze 142 5.6Preventing Protein Haze 151 References 159 6 Phenolic Compounds 161 6.1Introduction 161 6.2Types of Substances 162 6.3Chemical Properties of Anthocyanins and Tannins 173 6.4Anthocyanin and Tannin Assays: Sensory Properties 196 6.5Evolution of Anthocyanins and Tannins as Grapes Ripen 212 6.6Extracting Tannins and Anthocyanins During Winemaking 225 6.7Chemical Reactions Occurring During Bulk and Bottle Aging 228 6.8Precipitation of Coloring Matter (Color Stability) 233 6.9Origin of the Color of White Wines 235 References 238 7 Varietal Aroma 243 7.1The General Concept of Varietal Aroma 243 7.2Terpene Compounds 245 7.3C13-Norisoprenoid Derivatives 253 7.4Methoxypyrazines 257 7.5Sulfur Compounds with a Thiol Function 260 7.6Furanones 270 7.7Lactones 271 7.8Aromas of American Species 274 References 274 Part II – Wine Stabilization and Treatments 281 8 Main Sensory Defects: Chemical Nature, Origins and Consequences 283 8.1Introduction 283 8.2Oxidative Defects 285 8.3Effect of Various Forms of Bacterial Spoilage 289 8.4Microbiological Origin and Properties of Volatile Phenols 294 8.5Cork Taint 310 8.6Sulfur Derivatives and Reduction Odors 316 8.7Premature Aging of Wine Aroma 331 8.8Sensory Defects Associated with Grapes Affected by Various Types of Rot 336 8.9Miscellaneous Defects 343 References 346 9 The Concept of Clarity and Colloidal Phenomena 351 9.1Clarity and Stability 351 9.2The Colloidal State 354 9.3Colloid Reactivity 357 9.4Protective Colloids and Gum Arabic Treatment 363 References 368 10 Clarification and Stabilization Treatments: Fining Wine 369 10.1 Treating Wine 369 10.2 Sedimentation of Particles in Suspension 372 10.3 Racking: Role and Techniques 374 10.4 Theory of Protein Fining 377 10.5 Tannin-Protein Interactions 385 10.6 Effect of Fining on the Organoleptic Quality of Wine: Concept of Overfining 387 10.7 Products Used in Fining 389 10.8 Fining Techniques 396 10.9 Bentonite Treatment 398 10.10 Miscellaneous Clarification Treatments 403 References 406 11 Clarifying Wine by Filtration and Centrifugation 409 11.1 Principles of Filtration 410 11.2 Laws of Filtration 411 11.3 Methods for Assessing Clarification Quality 414 11.4 Filtration Equipment and Filter Aids 416 11.5 How Filter Layers Function 421 11.6 Filtration through Diatomaceous Earth (or Kieselguhr) Precoats 424 11.7 Filtration Through Cellulose-Based Filter Pads 431 11.8 Membrane Filtration 436 11.9 Crossflow Filtration 439 11.10 Effect of Filtration on the Composition and Organoleptic Character of Wine 443 11.11 Centrifugation 447 References 450 12 Stabilizing Wine by Physical and Physicochemical Processes 451 12.1 Introduction 451 12.2 Heat Stabilization 452 12.3 Wine Stabilization Through Physical Processes Under Development 455 12.4 Cold Stabilization 456 12.5 Ion Exchangers 459 12.6 Electrodialysis Applications in Winemaking 466 References 470 13 Aging Red Wines in Tanks and Barrels: Phenomena Occurring During Aging 471 13.1 Oxidation–Reduction Phenomena 471 13.2 Oxidation–Reduction Potential 473 13.3 Influence of Various Factors on Oxidation–Reduction Potential 478 13.4 Development of the Phenolic Characteristics of Red Wines (Color and Flavor) During Aging 484 13.5 Evolution of Aromatic Thiol Composition in Red Wines During Aging 492 13.6 Bottle Aging of Red Wines 498 13.7 Cellar Practices 505 13.8 Barrel Aging of Red Wines 508 13.9 Effect of Barrel Type on the Development of Red Wine 514 13.10 Constraints and Risks of Barrel Aging 525 References 527 Index 531