Keith Grainger - Wine Faults and Flaws

1 Cover

2 Title Page Wine Faults and Flaws: A Practical Guide Keith Grainger Consultant in Wines and Wine Technology Broadway, UK

3 Copyright

4 Dedication

5 Acknowledgements

6 Preface

7 Introduction References

8 1 Faults, Flaws, Off‐Flavours, Taints, and Undesirable Compounds 1.1 Introduction 1.2 Advances in Wine Technology in Recent Decades 1.3 Changes in Markets and the Pattern of Wine Consumption in Recent Decades 1.4 The Possible Impact of Some Fault Compounds Upon Human Health 1.5 Sulfur Dioxide and Other Possible Allergens 1.6 Faults and Taints 1.7 Distinguishing Between Faults and Flaws 1.8 Sensory Detection (Perception) Thresholds and Sensory Recognition Thresholds 1.9 Consumer Rejection Thresholds (CRTs) 1.10 Basic Categories of Wine Faults 1.11 Flaws 1.12 The Incidence of Wine Faults 1.13 ‘Faulty’ Wines that Exude Excellence 1.14 Final Reflections References

9 2 Wine Tasting 2.1 Introduction 2.2 Anosimics, Fatigue Effect, and Supertasters 2.3 Tasting Conditions, Equipment, and Glassware 2.4 The Use of a Structured Tasting Technique and Detection of Faults 2.5 Appearance 2.6 Nose 2.7 Palate 2.8 Assessment of Quality 2.9 Assessment of Readiness for Drinking/Potential for Ageing 2.10 Grading Wine – The Award of Points 2.11 Blind Tasting 2.12 Final Reflections References

10 3 Chloroanisoles, Bromoanisoles, and Halophenols 3.1 Introduction 3.2 Haloanisole Contaminations in the Food, Drinks, Water, and Pharmaceutical Industries 3.3 Haloanisole Contamination of Wines 3.4 The Economic and Reputational Costs to Wine Producers and the Wine Industry 3.5 Sensory Characteristics and Detection of Haloanisoles in Wine 3.6 The Haloanisoles Responsible and Their Detection Thresholds 3.7 The Formation Pathways of Haloanisoles from Halophenols 3.8 Contamination of Cork with TCA and Other Chloroanisoles 3.9 The Cork Industry in the Dock 3.10 The Cork Industry Begins to Address the Issues 3.11 The Cork Industry's Recent Initiatives for Haloanisole Prevention and Extraction 3.12 Winery and Cooperage Sources of Haloanisole Contamination in Wines 3.13 Laboratory Analysis for TCA and Other Haloanisoles in Corks and Wine 3.14 Prevention of Haloanisole Contamination of Wineries and Wines 3.15 Treatment of Wines Contaminated with Haloanisoles 3.16 Chlorophenols and Bromophenols as Taints 3.17 ‘Musty’ Taints Unrelated to Halophenols and Haloanisoles 3.18 Final Reflections References

11 4 Brettanomyces (Dekkera) and Ethyl Phenols 4.1 Introduction 4.2 Background and History 4.3 The Brett Controversy 4.4 Sensory Characteristics and Detection of Brettanomyces‐Related Compounds in Wine 4.5 The Origins of Brettanomyces and Formation of Related Compounds in Wines 4.6 The Danger Periods and Favourable Conditions for the Growth of Brettanomyces 4.7 Why Are Brettanomyces‐Related Compounds Found Mostly in Red Wines? 4.8 Prevention: Formulation and Implementation a Brett Control Strategy 4.9 Laboratory Analysis for Brettanomyces and Volatile Phenols 4.10 Treatment of Affected Wines 4.11 What the Future Might Hold for Microbiological Methods to Inhibit Brettanomyces? 4.12 Final Reflections References

12 5 Oxidation, Premox, and Excessive Acetaldehyde 5.1 Introduction 5.2 Oxidation in Must and Wine 5.3 Sensory Characteristics and Detection of Excess Acetaldehyde and Oxidation in Wine 5.4 Deliberately Oxidised and Highly Oxygenated Wines 5.5 Metal Ions and Substrates for Oxidation 5.6 Enzymatic Oxidation 5.7 Chemical Oxidation 5.8 Microbial Oxidation 5.9 Acetaldehyde 5.10 Sotolon 5.11 Oxygen Management in Winemaking 5.12 Oxygen Uptake During Cellar Operations 5.13 Containers and Closures 5.14 Pinking 5.15 Premature Oxidation (Premox) 5.16 Prevention of Excess Acetaldehyde and Oxidation 5.17 Additions of Ascorbic Acid: Antioxidant or Oxidising Agent? 5.18 Laboratory Analysis 5.19 Treatments 5.20 Final Reflections References

13 6 Excessive Sulfur Dioxide, Volatile Sulfur Compounds, and Reduced Aromas 6.1 Introduction 6.2 The Presence and Role of Sulfur, Sulfur Dioxide, Sulfite, and Sulfate in Wine Production 6.3 Excessive Sulfur Dioxide 6.4 Oxygen Management in Winemaking 6.5 Reduction in Wine: Positive and Negative 6.6 Hydrogen Sulfide 6.7 Prevention of Hydrogen Sulfide Formation 6.8 Treatment for Hydrogen Sulfide in Wine 6.9 Mercaptans, Sulfides, Disulfides, Trisulfides, and Thioesters 6.10 Post‐bottling Reduction 6.11 Lightstrike 6.12 Laboratory Analysis for Sulfur Dioxide, Hydrogen Sulfide, and Volatile Sulfur Compounds 6.13 Final Reflections References

14 7 Excessive Volatile Acidity and Ethyl Acetate 7.1 Introduction 7.2 Volatile Acidity and Ethyl Acetate 7.3 The Controversy of High Levels of Volatile Acidity 7.4 Fixed Acids and Volatile Acids 7.5 Sensory Characteristics and Detection of Volatile Acidity 7.6 Legal Limits 7.7 Acetic Acid Bacteria 7.8 Production of Acetic Acid in Wine 7.9 Ethyl Acetate 7.10 Prevention of Excessive Volatile Acidity and Ethyl Acetate 7.11 Laboratory Analysis 7.12 Treatments 7.13 Final Reflections References

15 8 Atypical Ageing (ATA) – Sometimes Called Untypical Ageing (UTA) 8.1 Introduction 8.2 The Atypical Ageing Controversy 8.3 The Causes of Atypical Ageing and Formation Pathways 8.4 Sensory Detection 8.5 Laboratory Detection 8.6 The Main Viticultural Causes of ATA 8.7 Prevention 8.8 Treatments 8.9 Final Reflections References

16 9 Fermentation in Bottle 9.1 Introduction 9.2 Sensory Detection 9.3 Alcoholic Fermentation in Bottle 9.4 Malolactic Fermentation (MLF) in Bottle 9.5 Prevention: Preparing Wine for Bottling and the Bottling Process 9.6 Treatment 9.7 Final Reflections References

17 10 Hazes 10.1 Introduction 10.2 Protein Haze 10.3 Microbial Hazes 10.4 Metal Hazes 10.5 Final Reflections References

18 11 Lactic Acid Bacteria‐Related Faults 11.1 Introduction to Lactic Acid Bacteria 11.2 Lactic Acid Bacteria and Their Natural Sources 11.3 Malolactic Fermentation (MLF) 11.4 Undesirable Aromas, Off‐Flavours, and Wine Spoilage Caused by Lactic Acid Bacteria 11.5 Prevention of Lactic Acid Bacteria‐Related Faults 11.6 Analysis 11.7 Final Reflections References

19 12 Smoke Taint and Other Airborne Contaminations 12.1 Introduction 12.2 Smoke Taint Compounds in the Atmosphere 12.3 Critical Times in the Growing Season and Duration of Exposure for Smoke Taint to Impact 12.4 The Volatile Phenols Responsible for Smoke Taint; Their Odours and Flavours and Sensory Detection Thresholds 12.5 Smoke Taint in Wines 12.6 Other Sources of Guaiacol and 4‐Methyl‐guaiacol in Wines 12.7 Laboratory Testing 12.8 Prevention of Development of Smoke‐Related Volatile Phenols from Affected Grapes 12.9 Treatments 12.10 Other Airborne Contaminations 12.11 Final Reflections References

20 13 Ladybeetle and Brown Marmorated Stink Bug Taints 13.1 Introduction 13.2 Methoxypyrazines 13.3 Ladybeetles (Also Known as Ladybirds and Ladybugs) 13.4 Brown Marmorated Stink Bug ( Halyomorpha halys ) Taint 13.5 Final Reflections References

21 14 Sundry Faults, Contaminants, Including Undesirable Compounds from a Health Perspective and Flaws Due to Poor Balance 14.1 Mycotoxins, Particularly Ochratoxin A 14.2 Dibutyl Phthalate and Other Phthalates 14.3 Ethyl Carbamate 14.4 Biogenic Amines 14.5 Ethyl Sorbate and Sorbyl Alcohol (Geraniol) Off‐Odours 14.6 Paper‐Taste 14.7 Plastic Taints – Styrene 14.8 Indole 14.9 Geosmin 14.10 2‐Bromo‐4‐methylphenol – Iodine, Oyster Taste 14.11 Heat Damage 14.12 Matters of Balance 14.13 Final Reflections References

22 15 TDN and Tartrate Crystals: Faults or Not? 15.1 TDN 15.2 Tartrate Deposits 15.3 Final Reflections References

23 16 Must Correction, Wine Correction, and Alcohol Reduction Using Membrane Technologies 16.1 Introduction 16.2 Membrane Processes Used in the Wine Industry 16.3 Clarification 16.4 Membrane Fouling 16.5 Must Correction, Wine Correction, and Alcohol Reduction 16.6 Fault Correction 16.7 Wine Stabilisation and pH Adjustment by Electrodialysis 16.8 Final Reflections References