Wine Faults and Flaws

Wine Faults and Flaws
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WINE FAULTS AND FLAWS Wine Faults and Flaws: A Practical Guide An essential guide to the faults and flaws that can affect wine Written by the award-winning wine expert, Keith Grainger, this book provides a detailed examination and explanation of the causes and impact of the faults, flaws and taints that may affect wine. Each fault is discussed using the following criteria: what it is; how it can be detected by sensory or laboratory analysis; what the cause is; how it might be prevented; whether an affected wine is treatable, and if so, how; and the science applicable to the fault.The incidences of faulty wines reaching the consumer are greater than would be regarded as acceptable in most other industries. It is claimed that occurrences are less common today than in recent recorded history, and it is true that the frequency of some faults and taints being encountered in bottle has declined in the last decade or two. However, incidences of certain faults and taints have increased, and issues that were once unheard of now affect many wines offered for sale. These include ‘reduced’ aromas, premature oxidation, atypical ageing and, very much on the rise, smoke taint.This book will prove invaluable to winemakers, wine technologists and quality control professionals. Wine critics, writers, educators and sommeliers will also find the topics highly relevant. The wine-loving consumer, including wine collectors will also find the book a great resource and the basis for discussion at tastings with like-minded associates.

Оглавление

Keith Grainger. Wine Faults and Flaws

Table of Contents

Guide

Pages

Wine Faults and Flaws: A Practical Guide

Acknowledgements

Preface

Introduction

References

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. 1.8.1 Sensory Detection Thresholds

1.8.2 Sensory Identification (Recognition) Thresholds

1.8.3 Odour Activity Values

1.9 Consumer Rejection Thresholds (CRTs)

1.10 Basic Categories of Wine Faults. 1.10.1 The Origin of Wine Faults

1.10.2 Microbiological Faults. 1.10.2.1 Types of Microorganisms Involved

Yeasts

Moulds

Bacteria

1.10.2.2 Examples of Microbiological Faults

1.10.2.3 Minimising the Occurrence Microbiological Faults

1.10.3 Chemical Nature Faults. 1.10.3.1 Examples of Chemical Faults

1.10.3.2 Minimising the Occurrence Chemical Faults

1.10.4 Physical Faults, Contamination, and Packaging Damage

1.11 Flaws. 1.11.1 Poor Wines, as a Consequence of Adverse Weather, Sub‐standard Viticulture, Careless Winemaking, or Inappropriate Additives

1.11.2 The Presence of ‘Fault’ Compounds at Low Concentrations

1.12 The Incidence of Wine Faults

1.13 ‘Faulty’ Wines that Exude Excellence

1.14 Final Reflections

References

2 Wine Tasting

2.1 Introduction

2.2 Anosimics, Fatigue Effect, and Supertasters. 2.2.1 Anosmics and Fatigue Effect

2.2.2 Supertasters

2.3 Tasting Conditions, Equipment, and Glassware. 2.3.1 The Tasting Room

2.3.2 Appropriate Equipment

2.3.2.1 Tasting Glasses

2.3.2.2 Glass Washing and Storage

2.3.2.3 Water

2.3.2.4 Spittoons

2.3.3 When to Taste

2.4 The Use of a Structured Tasting Technique and Detection of Faults

2.5 Appearance. 2.5.1 The Appearance Assessment

2.5.2 Clarity and Brightness

2.5.3 Intensity

2.5.4 Colour

2.5.4.1 White Wines

2.5.4.2 Rosé Wines

2.5.4.3 Red Wines

2.5.4.4 The Rim and Core

2.5.5 Other Observations

2.5.5.1 Bubbles or Petillance

Still Wines

Sparkling Wines

2.5.5.2 Legs

2.5.5.3 Deposits

2.6 Nose

2.6.1 Condition

2.6.2 Intensity

2.6.3 Aroma Types, Development, and Characteristics

2.6.3.1 Primary Aromas

2.6.3.2 Secondary Aromas

2.6.3.3 Tertiary Aromas

2.6.3.4 Aroma Characteristics

2.7 Palate. 2.7.1 Palate Sensations

2.7.2 Sweetness/Bitterness/Acidity/Saltiness/Umami/Trigeminal Sensations

2.7.3 Dryness/Sweetness

2.7.4 Acidity

2.7.5 Tannins

2.7.6 Alcohol

2.7.7 Body

2.7.8 Flavour Intensity

2.7.9 Flavour Characteristics

2.7.10 Other Observations. 2.7.10.1 Texture

2.7.10.2 Balance

2.7.11 Finish – Length

2.8 Assessment of Quality. 2.8.1 Quality Level

2.8.2 Reasons for Assessment of Quality

2.9 Assessment of Readiness for Drinking/Potential for Ageing. 2.9.1 The Life‐Cycle of a Wine

2.9.2 Level of Readiness for Drinking/Potential for Ageing

2.10 Grading Wine – The Award of Points. 2.10.1 Is the Awarding of Points Appropriate for Wines?

2.10.2 The Systems in Use

2.10.3 Nothing but a Snapshot Reflecting a Moment in Time

2.11 Blind Tasting. 2.11.1 Why Taste Blind?

2.11.2 Blind or Sighted?

2.11.3 Tasting for Quality

2.12 Final Reflections

References

3 Chloroanisoles, Bromoanisoles, and Halophenols

3.1 Introduction

3.2 Haloanisole Contaminations in the Food, Drinks, Water, and Pharmaceutical Industries

3.2.1 Haloanisole Contamination of Pharmaceutical Products

3.2.2 Haloanisole Contamination of Food and Non‐Alcoholic Drinks

3.2.3 Haloanisoles in Tap Water and Bottled Water

3.3 Haloanisole Contamination of Wines

3.4 The Economic and Reputational Costs to Wine Producers and the Wine Industry

3.4.1 The Economic Cost to the Industry at Large

3.4.2 The Economic and Reputational Cost to Individual Wine Producers

3.4.3 The Nightmare of Haloanisole Contaminated Wineries and Cellars

3.4.3.1 California Pays a High Price

3.4.3.2 Affluence and Crisis in Bordeaux

3.4.3.3 Cellar Contaminations in South America

3.5 Sensory Characteristics and Detection of Haloanisoles in Wine

3.5.1 The Odours and Tastes of Haloanisoles in Wine

3.5.2 Variance in Sensory Detection Thresholds and Consumer Rejection Thresholds

3.6 The Haloanisoles Responsible and Their Detection Thresholds

3.6.1 The Main Haloanisoles Responsible

3.6.2 2,4,6‐Trichloroanisole (TCA)

3.6.3 2,3,4,6‐Tetrachloroanisole (TeCA)

3.6.4 Pentachloroanisole (PCA)

3.6.5 2,4,6‐Tribromoanisole (2,4,6‐TBA)

3.7 The Formation Pathways of Haloanisoles from Halophenols. 3.7.1 Origins

3.7.1.1 Chlorophenols

3.7.1.2 Bromophenols

3.7.2 The Biological Transformation of Halophenols into Haloanisoles

3.7.3 The Role of the Pesticides, Herbicides, and Fungicides. 3.7.3.1 Chlorophenol‐Based Products

3.7.3.2 Bromophenol‐Based Products

3.7.3.3 Restrictions on Usage of Chlorophenols and Bromophenols

3.7.3.4 The Advent of Chloroanisole and Bromoanisole Wine Contamination

3.7.3.5 Other Halophenol Formation Pathways

3.7.4 The Fungi that Convert Halophenols into Haloanisoles

3.8 Contamination of Cork with TCA and Other Chloroanisoles

3.8.1 Cork Production and How Cork Becomes Contaminated

3.8.2 The Transmission of TCA from Corks to Wine

3.8.3 The Historic Incidences of So‐Called ‘Cork Taint’ and the Role of the Cork Industry

3.8.4 The Rise in Incidences of So‐Called ‘Cork Taint’

3.9 The Cork Industry in the Dock. 3.9.1 The Industry in Denial

3.9.2 Hostile Coverage in the Wine Press

3.9.3 Alternative Closures to the Fore

3.10 The Cork Industry Begins to Address the Issues. 3.10.1 Cork Producers Fight Back

3.10.2 Many Wine Professionals Remain Hostile to Cork

3.11 The Cork Industry's Recent Initiatives for Haloanisole Prevention and Extraction. 3.11.1 Investment and Initiatives by the Stakeholders

3.11.2 Symbios

3.11.3 Methods to Extract TCA During Cork Production

3.11.3.1 Analysis and Rejection of Bark Affected by Chloroanisoles

3.11.3.2 Changes in Boiling Systems

3.11.3.3 Chloroanisole Removal by Steam Vaporisation

3.11.3.4 Extraction with Supercritical Carbon Dioxide

3.11.3.5 NDtech

3.11.3.6 Other Companies' Non‐Detectable TCA' Guarantees

3.12 Winery and Cooperage Sources of Haloanisole Contamination in Wines

3.12.1 Winery Environment, Structure, Sundry Items, and Routine Processes as Sources of Contamination

3.12.2 Oak Barrels as a Source of Haloanisole Contamination of Wine

3.12.3 Processing Aids and Additives as Sources of Contamination

3.13 Laboratory Analysis for TCA and Other Haloanisoles in Corks and Wine. 3.13.1 Haloanisoles in Wine and Releasable and Total TCA in Corks

3.13.2 Laboratory Methods of Analysis

3.13.2.1 Sample Preparation

3.13.2.2 Separation and Quantification

3.13.2.3 Bioanalytical Methods

3.13.3 Inexpensive Alternatives

3.14 Prevention of Haloanisole Contamination of Wineries and Wines. 3.14.1 Implementation of an HACCP System

3.14.2 In the Vineyard

3.14.3 In the Winery

3.14.3.1 Cleaning and Sanitising

3.14.3.2 Avoidance of Chlorine and Bromine

3.14.3.3 Monitoring of Tap Water

3.14.3.4 Air Renewal and Humidity Control

3.14.3.5 Prohibition of PCP and 2,4,6‐TBP

3.14.3.6 Diligence with Regard to Oenological Products and Processing Aids

3.14.3.7 Periodic Inspections and Testing of Production and Storage Areas

3.14.3.8 Attention to the Barrel Room, Cellar, and Storage

3.14.3.9 Regular Sensory Analysis of Wine Stock

3.14.3.10 Training Cellar Staff for Haloanisole Detection

3.14.4 Cork Screening and Group Cork Soaks

3.15 Treatment of Wines Contaminated with Haloanisoles

3.15.1 Fining with Half and Half

3.15.2 Filtration Using Zeolites Y‐Faujasites

3.15.3 Absorption/Adsorption/Filtration Using Polymeric Media. 3.15.3.1 Use of Polythene Resin Beads and Polymer ‘Fining’

3.15.3.2 Filtration Using Adsorbing Polymers

3.15.3.3 Adsorption by Polyvinylidene Chloride (PVdC)

3.15.4 Adsorbing by Yeast Hulls

3.15.5 Filtration Through Cork Dust

3.15.6 Deodorising with Mustard Seeds

3.16 Chlorophenols and Bromophenols as Taints

3.16.1 The Odours of Chlorophenols and Bromophenols

3.16.2 2,4‐Dichlorophenol

3.16.3 2,6‐Dichlorophenol

3.16.4 2,4,6‐Trichlorophenol

3.16.5 6‐Chloro‐o‐cresol

3.16.6 2‐Bromophenol

3.16.7 2,6‐Dibromophenol

3.16.8 2,4,6‐Tribromophenol

3.17 ‘Musty’ Taints Unrelated to Halophenols and Haloanisoles. 3.17.1 Other Musty Taints in Wine

3.17.2 2‐Methoxy‐3,5‐dimethylpyrazine (MDMP) or ‘Fungal Must Taint’

3.17.3 2‐Isopropyl‐3‐methoxypyrazine

3.17.4 2‐Methoxy‐3‐isopropylpyrazine

3.17.5 2‐Methylisoborneol (MIB)

3.17.6 1‐Octen‐3‐ol

3.17.7 1‐Octen‐3‐one

3.17.8 1‐Octen‐2‐one

3.17.9 cis‐1,5‐Octadien‐3‐one

3.17.10 cis‐1,5‐Octadien‐3‐ol

3.17.11 Geosmin

3.17.12 ‘Musty’ Monoterpenes and Sesquiterpenes

3.17.13 Guaiacol

3.17.14 Treatment of Musty Taints Unrelated to Halophenols and Haloanisoles

3.18 Final Reflections

References

4 Brettanomyces(Dekkera) and Ethyl Phenols

4.1 Introduction

4.2 Background and History

4.3 The Brett Controversy. 4.3.1 Brettanomyces Paranoia?

4.3.2 The Role of Brettanomyces in Craft and Lambic Beer Production

4.3.3 Brettanomyces: An Extension of Terroir?

4.3.4 Artisans Choosing Brettanomyces for Wine Fermentations

4.3.5 Some Wines with a Notable Brett Influence

4.3.6 An Old World/New World Divide?

4.3.7 Good Brett/Bad Brett?

4.4 Sensory Characteristics and Detection of Brettanomyces‐Related Compounds in Wine

4.4.1 The Odours Associated with Brettanomyces‐Related Compounds

4.4.2 Sensory Detection Thresholds

4.4.3 4‐Ethylphenol (4‐EP)

4.4.4 4‐Ethylguaiacol (4‐EG)

4.4.5 Isovaleric Acid and Isobutyric Acid

4.4.6 4‐Ethylcatechol

4.4.7 Tetrahydropyridines Particularly 2‐Acetyltetrahydropyridine (ATHP) and 2‐Ethyltetrahydropyridine (ETHP)

4.4.8 Guaiacol

4.4.9 The Impact of the Wine Matrix

4.5 The Origins of Brettanomyces and Formation of Related Compounds in Wines. 4.5.1 Microflora on Grapes and Present in Wineries

4.5.2 The Formation Pathways of Brettanomyces‐Related Compounds. 4.5.2.1 Hydroxycinnamic Acids Precursors

4.5.2.2 The Formation of Vinyl Phenols

4.5.2.3 The Formation of Ethyl Phenols

4.6 The Danger Periods and Favourable Conditions for the Growth of Brettanomyces. 4.6.1 The Danger During Winemaking and Cellar Maturation

4.6.2 Growth in Bottle

4.7 Why Are Brettanomyces‐Related Compounds Found Mostly in Red Wines?

4.8 Prevention: Formulation and Implementation a Brett Control Strategy. 4.8.1 HACCP

4.8.2 The Vineyard

4.8.3 Harvest

4.8.4 The Winery

4.8.5 Winemaking Practices. 4.8.5.1 Approaches to Brettanomyces Management

4.8.5.2 Pre‐fermentation

4.8.5.3 Cold Soaks and Hot Pre‐fermentation Maceration

4.8.5.4 Yeast Starters, Nutrients, and Enzymes

4.8.5.5 The Alcoholic Fermentation (AF), Post‐Fermentation Period, and Pressing

4.8.5.6 The Pre‐MLF Lag Phase and the MLF

4.8.6 Maturation, Barrel Ageing, and Barrel Care. 4.8.6.1 Barrel Maturation

4.8.6.2 Barrel Cleaning and Sanitising

4.8.6.3 Methods of Barrel Cleaning

4.8.6.4 Topping Up Barrels

4.8.6.5 Temperature of the Barrel Store

4.8.7 Maintaining Appropriate Molecular Sulfur Dioxide Levels. 4.8.7.1 The Sulfur Dioxide Quandary

4.8.7.2 Appropriate Levels of Molecular Sulfur Dioxide

4.8.8 Racking

4.8.9 Fining

4.8.10 Filtration

4.8.11 Bottling

4.8.12 Storage

4.9 Laboratory Analysis for Brettanomyces and Volatile Phenols

4.9.1 When Analysis Should Be Undertaken

4.9.2 Analysis for Viable Yeast Cells

4.9.2.1 Plate Cultures

4.9.2.2 Fluorescence Microscopy

4.9.2.3 Polymerase Chain Reaction (qPCR)

4.9.2.4 Flow Cytometry and Fluorescence In Situ Hybridisation

4.9.2.5 Raman Spectroscopy

4.9.2.6 Experimental Technologies for Detection of Brettanomyces

4.9.3 Analysis for Volatile Phenols Using Gas Chromatography with Detection by Mass Spectroscopy (GC‐MS)

4.10 Treatment of Affected Wines

4.10.1 Reduction or Removal of Brettanomyces Cells. 4.10.1.1 Racking

4.10.1.2 Fining

4.10.1.3 Filtration

4.10.1.4 Heat Treatments

4.10.1.5 Chemical Treatments

4.10.2 Reduction in Volatile Phenols

4.10.3 Future Possibilities for Physical Brett Inactivation

4.11 What the Future Might Hold for Microbiological Methods to Inhibit Brettanomyces?

4.12 Final Reflections

References

5 Oxidation, Premox, and Excessive Acetaldehyde

5.1 Introduction. 5.1.1 Oxygen: The Enemy and the Friend

5.1.2 The Importance of Oxygen in Winemaking

5.1.3 Oxygenation Is Not Oxidation

5.1.4 Good and Bad Oxidation?

5.2 Oxidation in Must and Wine. 5.2.1 Oxidation Defined

5.2.2 Types of Oxidation

5.3 Sensory Characteristics and Detection of Excess Acetaldehyde and Oxidation in Wine. 5.3.1 Excess Acetaldehyde. 5.3.1.1 Background

5.3.1.2 Detection

5.3.1.3 Appearance

5.3.1.4 Nose

5.3.1.5 Palate

5.3.1.6 Sensory Detection Threshold

5.3.2 Oxidation

5.3.2.1 Appearance

5.3.2.2 Nose

5.3.2.3 Palate

5.4 Deliberately Oxidised and Highly Oxygenated Wines. 5.4.1 Fortified and Speciality Wines

5.4.1.1 Speciality Unfortified Wines

5.4.1.2 Fortified Wines

5.4.2 Deliberate Oxidation in High‐Quality ‘Table’ Wines

5.4.3 The Strange Case of Orange Wines

5.4.4 Grape Varieties Susceptible to Oxidation

5.5 Metal Ions and Substrates for Oxidation. 5.5.1 The Role of Metal Ions

5.5.2 Substrates for Oxidation

5.5.3 Classes of Phenolics

5.5.3.1 Flavonoids

5.5.3.2 Non‐flavonoids

5.6 Enzymatic Oxidation. 5.6.1 Substrates

5.6.2 Polyphenol Oxidases, Tyrosinase, and Laccase

5.6.3 Glutathione and Grape Reaction Product (GRP)

5.6.4 Prevention of Tyrosinase‐Catalysed Enzymatic Oxidation

5.6.5 Laccase

5.6.6 Hyperoxygenation

5.7 Chemical Oxidation

5.7.1 Substrates

5.7.2 Chemical Oxidation Pathways

5.8 Microbial Oxidation

5.9 Acetaldehyde

5.9.1 Biological Production

5.9.2 Chemical Production

5.9.3 Acceptable and Unacceptable Levels of Acetaldehyde

5.9.4 Binding of Sulfur Dioxide

5.10 Sotolon

5.11 Oxygen Management in Winemaking

5.11.1 The Role of Oxygen During Fermentation

5.11.2 Post‐fermentation Oxygenation

5.11.3 Barrel Maturation

5.11.4 Lees Ageing

5.12 Oxygen Uptake During Cellar Operations

5.13 Containers and Closures

5.14 Pinking

5.15 Premature Oxidation (Premox) 5.15.1 Premature Oxidation Rears Its Head

5.15.2 Reversible Oxidation?

5.15.3 Causes of Premature Oxidation. 5.15.3.1 Possible Causes

5.15.3.2 Clonal Selection

5.15.3.3 The Phenolic Ripeness and High pH of Fruit

5.15.3.4 Low Levels of Glutathione in Grapes

5.15.3.5 The Use of Pneumatic Presses

5.15.3.6 The Increased Use of New Oak Barrels

5.15.3.7 Bâtonnage

5.15.3.8 Insufficient Free Sulfur Dioxide Levels

5.15.3.9 Interventionist Operations Undertaken to Speed the Wine to Market

5.15.3.10 Ingress of Oxygen When Bottling

5.15.3.11 Low‐Quality Cork Closures and Corks Washed with Peroxide

5.15.4 Prune Aroma

5.16 Prevention of Excess Acetaldehyde and Oxidation. 5.16.1 Basic Principles

5.16.2 Picking at Appropriate Ripeness

5.16.3 Harvesting and Transporting Fruit

5.16.4 Sorting

5.16.5 Crushing

5.16.6 Pressing (for White Wines)

5.16.7 Juice Clarification (White Must)

5.16.8 Inoculate with Commercial Strains of Saccharomyces

5.16.9 Fermentation

5.16.10 Post‐fermentation Maceration

5.16.11 Malolactic Fermentation (MLF)

5.16.12 Avoiding Ullage in Tanks and Barrels

5.16.13 Reducing Oxygen Uptake in Cellar Operations Including Rackings and Transfers

5.16.14 Maintaining Appropriate Levels of Free SO2

5.16.15 Reducing Heavy Metals

5.16.16 Controlling Cellar Temperature and Humidity

5.16.17 Barrel Ageing and/or the Addition of Ellagitannins

5.16.18 Lees Ageing

5.16.19 Cold Stabilisation

5.16.20 Ultrafiltration Before Bottling

5.16.21 Bottling. 5.16.21.1 A Major Source of Oxygen Uptake

5.16.21.2 Total Package Oxygen (TPO)

5.16.21.3 Dissolved Oxygen in the Wine

5.16.21.4 Oxygen in the Empty Bottle Pre‐filling

5.16.21.5 Headspace Oxygen

5.16.21.6 Oxygen Content of the Closure

5.16.21.7 Addition of Glutathione Prior to Bottling

5.16.22 Storage. 5.16.22.1 Oxygenation During Storage

5.16.22.2 Oxidation Due to Poor Storage

5.17 Additions of Ascorbic Acid: Antioxidant or Oxidising Agent?

5.18 Laboratory Analysis. 5.18.1 Acetaldehyde

5.18.2 Dissolved Oxygen

5.18.3 Oxidation

5.19 Treatments. 5.19.1 Acetaldehyde

5.19.2 Oxidation

5.20 Final Reflections

References

6 Excessive Sulfur Dioxide, Volatile Sulfur Compounds, and Reduced Aromas

6.1 Introduction. 6.1.1 Volatile Sulfur Compounds

6.1.2 Thiols

6.2 The Presence and Role of Sulfur, Sulfur Dioxide, Sulfite, and Sulfate in Wine Production

6.2.1 Sulfur Contained in Grapes

6.2.2 Sulfur‐Containing Fungicides

6.2.3 Sulfur Dioxide Generated by Yeast During Fermentation

6.2.3.1 Sulfur‐Containing Amino Acid

6.2.4 Additions of Sulfur Dioxide During the Winemaking Process. 6.2.4.1 The Use of Sulfur Dioxide in Winemaking

6.2.4.2 Total, Bound, Free, and Molecular Sulfur Dioxide

6.2.4.3 Additions of Sulfur Dioxide to Prevent Enzymatic Oxidation

6.2.4.4 The Use of Sulfur Dioxide to Prevent Chemical and Microbial Oxidation

6.3 Excessive Sulfur Dioxide. 6.3.1 High Levels of SO2: Flaw or Fault?

6.3.2 Sensory Detection of Excess Sulfur Dioxide

6.3.3 Possible Reasons for High SO2 Levels

6.3.4 Removal of Excessive Sulfur Dioxide from Wine

6.4 Oxygen Management in Winemaking

6.4.1 The Role and Management of Oxygen During Fermentation

6.4.2 Oxygenating During Fermentation

6.4.3 Micro‐oxygenation During Fermentation

6.4.4 Micro‐oxygenation Post‐fermentation

6.4.5 Barrel Maturation

6.4.6 Lees Ageing

6.5 Reduction in Wine: Positive and Negative. 6.5.1 Reducing Agents

6.5.2 Positive Reduction. 6.5.2.1 Reduced Notes as a Hallmark?

6.5.2.2 Desirable Aromas of Some VSCs

6.5.2.3 Minerality

6.5.3 Negative Reduction

6.6 Hydrogen Sulfide. 6.6.1 Hydrogen Sulfide: A Serious Fault When Present Above Sensory Threshold

6.6.2 Sensory Characteristics and Detection of Hydrogen Sulfide in Wine

6.6.3 The Formation of Hydrogen Sulfide in Wine

6.6.3.1 Formation by the Actions of Yeasts During the Alcoholic Fermentation

6.6.3.2 Production by Reduction of Elemental Sulfur or Inorganic Sulfur

6.7 Prevention of Hydrogen Sulfide Formation

6.8 Treatment for Hydrogen Sulfide in Wine

6.8.1 Physical Treatments. 6.8.1.1 Splash Racking

6.8.1.2 Aeration or Inert Gas Bubbling

6.8.2 Chemical Additions as Treatments

6.8.2.1 Sulfiting

6.8.2.2 Use of an Oxidising Agent

Copper Sulfate Pentahydrate

Copper Citrate

Legal Restrictions on the Use of Copper

Silver Chloride

Silicon Dioxide

6.9 Mercaptans, Sulfides, Disulfides, Trisulfides, and Thioesters. 6.9.1 Low‐ and High‐Boiling‐Point VSCs

6.9.2 Mercaptans

6.9.2.1 Methanethiol, Also Known as Methyl Mercaptan (MeSH)

6.9.2.2 Ethanethiol, Also Known as Ethyl Mercaptans (EtSH)

6.9.3 Sulfides Other than H2S. 6.9.3.1 Dimethyl Sulfide (DMS)

6.9.3.2 Ethyl Sulfide

6.9.3.3 Diethyl Sulfide

6.9.4 Disulfides

6.9.4.1 Carbon Disulfide

6.9.4.2 Diethyl Disulfide

6.9.4.3 Dimethyl Disulfide (DMDS)

6.9.5 Trisulfides: Dimethyl Trisulfide (DMTS)

6.9.6 Thioesters

6.9.6.1 Methyl Thioacetate

6.9.6.2 Ethyl Thioacetate

6.10 Post‐bottling Reduction. 6.10.1 A New Wine Fault

6.10.2 The Causes of Post‐bottling Reduction

6.10.3 The Oxygen Transmission Rates (OTRs) of Closures

6.11 Lightstrike

6.11.1 Wines Likely to Be Affected by Lightstrike

6.11.2 Sensory Detection

6.11.3 Causes and Incidences of the Fault. 6.11.3.1 The Transmission of UV Light Through Clear Glass Bottles

6.11.3.2 The Role of Riboflavin, Sulfur‐Containing Amino Acids, and Iron Tartrate

6.11.4 Prevention of Lightstrike

6.11.4.1 Vinification Measures

6.11.4.2 Packaging Measures

6.11.4.3 Storage Measures

6.11.5 Treatment

6.12 Laboratory Analysis for Sulfur Dioxide, Hydrogen Sulfide, and Volatile Sulfur Compounds. 6.12.1 Sulfur Dioxide

6.12.2 Hydrogen Sulfide and Volatile Sulfur Compounds. 6.12.2.1 A Quick and Easy Test for H2S Using Copper Sulfate

6.12.2.2 The Copper/Cadmium Test for H2S, Mercaptans (–SH Group), Disulfides, and Dimethyl Sulfide

Solutions:

Procedure:

6.12.2.3 Gas Chromatography

6.13 Final Reflections

References

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. 7.3.1 Are Elevated Levels of Volatile Acidity Sometimes Acceptable?

7.3.2 1947 Château Cheval Blanc – The Greatest Faulty Wine Ever Made

7.4 Fixed Acids and Volatile Acids. 7.4.1 Total Acidity

7.4.2 Fixed Acids

7.4.2.1 Tartaric Acid

7.4.2.2 Citric Acid

7.4.2.3 Malic Acid

7.4.2.4 Lactic Acid

7.4.2.5 Succinic Acid

7.4.3 Volatile Acids

7.4.3.1 Acetic Acid

7.4.3.2 Butyric Acid

7.4.3.3 Isobutyric Acid

7.4.3.4 Propionic Acid

7.4.3.5 Hexanoic Acid

7.4.3.6 Sorbic Acid

7.4.3.7 Sulfurous Acid

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

7.8.1 Microbiological Production. 7.8.1.1 Production by Yeasts

7.8.1.2 Production by Bacteria, Including Acetic Acid Bacteria

7.8.2 Physiochemical Production

7.9 Ethyl Acetate

7.9.1 Production of Ethyl Acetate in Wine

7.9.2 Microbiological Production. 7.9.2.1 Production by Yeasts

7.9.2.2 Production by Acetic Acid Bacteria

7.9.3 Chemical Production

7.9.4 New Barrels Do Not Contain Ethyl Acetate

7.9.5 Sensory Characteristics and Detection of Ethyl Acetate

7.10 Prevention of Excessive Volatile Acidity and Ethyl Acetate

7.10.1 Fruit Selection and Processing

7.10.2 Exclusion of Vectors

7.10.3 Cleaning

7.10.4 Avoiding Cross‐Contamination

7.10.5 Must Adjustment Including Nutrient Additions

7.10.6 Addition of Lysozyme

7.10.7 Cold Soaking (Red Wines)

7.10.8 Inoculation with Desired Strains of Saccharomyces cerevisiae

7.10.9 Alcoholic Fermentation

7.10.10 Malolactic Fermentation

7.10.11 Addition of Sulfur Dioxide and Maintaining Appropriate Molecular SO2

7.10.12 Avoiding Ullage in Vats and Barrels

7.10.13 Micro‐oxygenation

7.10.14 Cleaning and Sanitising Barrels that Show Signs of Acetic Acid

7.10.15 Cautious Use of Citric Acid

7.10.16 Avoiding the Growth of Brettanomyces

7.10.17 Minimising Oxygen Uptake During Cellar Operations

7.10.18 Barrel Ageing

7.10.19 Monitoring and Analysis

7.10.20 Bottling

7.11 Laboratory Analysis. 7.11.1 Volatile Acidity and Acetic Acid Bacteria

7.11.2 Laboratory Analysis – Ethyl Acetate

7.12 Treatments. 7.12.1 Excessive Volatile Acidity

7.12.1.1 Dealing with Rising Levels of VA

7.12.1.2 Blending

7.12.1.3 Fining

7.12.1.4 Nanofiltration Coupled with Ion Exchange

7.12.1.5 Reverse Osmosis

7.12.1.6 Future Possibilities of Bio‐reduction of VA Levels

7.12.2 Ethyl Acetate

7.13 Final Reflections

References

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. 8.3.1 The Role of 2‐Aminoacetophenone (2‐AAP)

8.3.2 The Formation of 2‐AAP

8.3.3 The Role of Other Chemical Compounds

The Involvement of Sotolon, Phenylacetaldehyde

8.3.4 Distinguishing ATA from Premature Oxidation (Premox), and Reduction

8.4 Sensory Detection. 8.4.1 Sensory Characteristics

8.4.2 Sensory Perception Threshold of 2‐AAP

8.5 Laboratory Detection

8.6 The Main Viticultural Causes of ATA

8.7 Prevention. 8.7.1 In the Vineyard

8.7.2 In the Winery

8.7.3 Ascorbic Acid Addition

8.8 Treatments

8.9 Final Reflections

References

9 Fermentation in Bottle

9.1 Introduction. 9.1.1 Bottle–Fermented Sparkling Wines

9.1.2 Pétillant–Naturels

9.1.3 Unwanted Bottle Fermentation

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

9.5.1 Preparing Wine for Bottling. 9.5.1.1 Fining and Other Clarification

9.5.1.2 Adjustment of Free and Molecular SO2

9.5.1.3 Addition of a Fermentation Inhibitor

Lysozyme

Dimethyl Dicarbonate (DMDC) (Velcorin)

Potassium Sorbate

9.5.1.4 Heat Treatments

9.5.1.5 Membrane Filtration

9.5.2 The Bottling Process. 9.5.2.1 The Final Production Source of Contamination

9.5.2.2 The Bottling Line and Operation

9.6 Treatment

9.7 Final Reflections

References

10 Hazes

10.1 Introduction

10.2 Protein Haze. 10.2.1 The Formation and Impact of Protein Hazes

10.2.2 Prevention of Protein Haze Formation. 10.2.2.1 Pre‐fermentation Reduction in Haze‐Forming Proteins

10.2.2.2 Post‐fermentation Reduction in Haze‐Forming Proteins

10.2.2.3 Testing for Protein Stability

Heat (Stability) Tests

Reagent‐Based Tests

10.2.2.4 Fining with Bentonite

Fining Trials

Bentonite Additions

10.2.2.5 Alternatives to Bentonite. Ultrafiltration

The Use of Chitosan and Chitin–Glucan

10.2.2.6 Possible Future Alternatives to Bentonite

10.3 Microbial Hazes

10.4 Metal Hazes

10.4.1 Copper Haze. 10.4.1.1 Formation of Copper Haze

10.4.1.2 Prevention/Removal of Copper Haze

10.4.2 Iron Haze. 10.4.2.1 Formation of Iron Haze

10.4.2.2 Prevention/Removal of Iron Haze

10.5 Final Reflections

References

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) 11.3.1 History of the Understanding MLF

11.3.2 The MLF Process

11.3.2.1 Temperature

11.3.2.2 Sulfur Dioxide (SO2)

11.3.2.3 pH

11.3.2.4 Alcohol

11.3.2.5 Nutrients

11.4 Undesirable Aromas, Off‐Flavours, and Wine Spoilage Caused by Lactic Acid Bacteria. 11.4.1 Off‐Odours Associated with Lactic Acid Bacteria

11.4.2 Acrolein

11.4.3 Excess Diacetyl

11.4.4 Mannitol

11.4.5 Ropiness

11.4.6 Mousiness

11.4.7 Tourne

11.4.8 Indole

11.4.9 Geranium Taste

11.5 Prevention of Lactic Acid Bacteria‐Related Faults

11.6 Analysis

11.7 Final Reflections

References

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

12.9.1 Activated Carbon

12.9.2 Other Fining Treatments

12.9.3 Reverse Osmosis (RO) and Solid Phase Adsorption

12.9.4 The Addition of Oak Products to Affected Wines

12.9.5 Blending

12.9.6 Limiting Time in Bottle Pre‐sale

12.10 Other Airborne Contaminations. 12.10.1 Spray Drift

12.10.2 Eucalyptol – 1,8‐Cineole

12.10.2.1 Prevention

12.11 Final Reflections

References

13 Ladybeetle and Brown Marmorated Stink Bug Taints

13.1 Introduction

13.2 Methoxypyrazines

13.3 Ladybeetles (Also Known as Ladybirds and Ladybugs) 13.3.1 Background

13.3.2 Infested Grapes

13.3.3 Sensory Characteristics, Detection, and Consumer Rejection Thresholds. 13.3.3.1 Sensory Characteristics

13.3.3.2 Sensory Detection Thresholds and Consumer Rejection Thresholds

13.3.4 Prevention

13.3.5 Treatments

13.4 Brown Marmorated Stink Bug (Halyomorpha halys) Taint. 13.4.1 Background

13.4.2 Infested Grapes

13.4.3 Sensory Characteristics, Detection, and Consumer Rejection Thresholds. 13.4.3.1 Sensory Characteristics

13.4.3.2 Sensory Detection Thresholds and Consumer Rejection Thresholds (CRT)

13.4.4 Prevention

13.4.5 Treatments

13.5 Final Reflections

References

14 Sundry Faults, Contaminants, Including Undesirable Compounds from a Health Perspective and Flaws Due to Poor Balance

14.1 Mycotoxins, Particularly Ochratoxin A

14.1.1 The Presence of Ochratoxin A

14.1.2 The Origins of Ochratoxin A in Wines

14.1.3 Prevention of, or Minimising, Contamination with OTA

14.1.4 Analysis

14.1.5 Treatment of Affected Wines

14.2 Dibutyl Phthalate and Other Phthalates

14.3 Ethyl Carbamate

14.3.1 Production of Ethyl Carbamate in Wines

14.3.2 Prevention of Ethyl Carbamate in Wines

14.3.3 Analysis

14.4 Biogenic Amines

14.5 Ethyl Sorbate and Sorbyl Alcohol (Geraniol) Off‐Odours. 14.5.1 The Use of Potassium Sorbate and Conversion to Compounds Giving Off‐Odours

14.5.2 Prevention

14.6 Paper‐Taste

14.7 Plastic Taints – Styrene

14.8 Indole. 14.8.1 The Presence of Indole in Wine

14.8.2 Sensory Perception

14.9 Geosmin. 14.9.1 Sources of Geosmin in Wine

14.9.2 Organoleptic Detection and Sensory Perception Thresholds

14.9.3 Treatment

14.10 2‐Bromo‐4‐methylphenol – Iodine, Oyster Taste

14.11 Heat Damage. 14.11.1 Transport and Storage

14.11.2 Sensory Detection

14.11.3 Pathways to Heat Damage

14.12 Matters of Balance. 14.12.1 Unbalanced Wines May Be Regarded as Flawed

14.12.2 Alcohol

14.12.3 Acidity

14.12.4 Body and Structure

14.12.5 Tannins

14.12.6 Fruit and Flavour Concentration

14.12.7 Residual Sugar (If Any)

14.13 Final Reflections

References

15 TDN and Tartrate Crystals: Faults or Not?

15.1 TDN. 15.1.1 What Is TDN?

15.1.2 The Formation of TDN

15.1.3 Sensory Characteristics and Sensory Detection Thresholds. 15.1.3.1 Sensory Characteristics

15.1.3.2 Sensory Detection Thresholds

15.1.3.3 Prevalence of TDN in Riesling Wines

15.1.4 Minimising TDN in Wine Production

15.1.5 TDN in Bottled Wine

15.1.6 The TDN Controversy

15.2 Tartrate Deposits

15.2.1 The Formation of Tartrate Deposits

15.2.2 Sources of Calcium in Wines

15.2.3 Calcium Tartrate Instability

15.2.4 Sources of Potassium in Wines

15.2.5 Potassium Bitartrate Instability

15.2.6 Prevention of Tartrate Formation

15.2.7 Prevention of Precipitation of Potassium Bitartrate Crystals in Packaged Wine. 15.2.7.1 Methods Used for KHT Stabilisation

15.2.7.2 Cold Stabilisation

15.2.7.3 Ion Exchange

15.2.7.4 Electrodialysis

15.2.7.5 Metatartaric Acid Addition

15.2.7.6 Carboxymethylcellulose (CMC)

15.2.7.7 Mannoproteins

15.2.7.8 Potassium Polyaspartate (KPA)

15.2.7.9 Considerations as to the Choice of Methods of Prevention of KHT Crystallisation

15.2.7.10 Gum Arabic and Co‐blends of Additives

15.2.8 Prevention of Precipitation of Calcium Tartrate Crystals in Packaged Wine. 15.2.8.1 Methods Permitted by the OIV

15.2.8.2 The Addition of Calcium Tartrate

15.2.8.3 The Addition of Racemic (DL) Tartaric Acid

15.2.9 Predictive Tests. 15.2.9.1 Potassium Bitartrate

15.2.9.2 Calcium Tartrate

15.3 Final Reflections

References

16 Must Correction, Wine Correction, and Alcohol Reduction Using Membrane Technologies

16.1 Introduction. 16.1.1 The Use of Membranes in Stabilising Wines for Export Markets

16.1.2 Wine as a ‘Natural’ Product

16.2 Membrane Processes Used in the Wine Industry

16.3 Clarification. 16.3.1 ‘Traditional’ Clarification and Filtration Methods in Common Use

16.3.2 Membrane Filtration of Must and Wine. 16.3.2.1 Clarification of Must

16.3.2.2 Clarification of Wine

16.3.3 Cross‐Flow Micro Filtration

16.4 Membrane Fouling

16.5 Must Correction, Wine Correction, and Alcohol Reduction. 16.5.1 Reverse Osmosis

16.5.1.1 Must Correction by RO – Increasing Sugar Concentration

16.5.1.2 Must Correction by RO, Ultrafiltration/Nanofiltration – Reducing Sugar Concentration

16.5.2 Ultrafiltration

16.5.3 Wine Correction – Reducing Alcohol Content

16.6 Fault Correction. 16.6.1 Removing Acetic Acid

16.6.2 Removal of Brettanomyces Yeasts, and the Treatment of Volatile Phenols

16.6.3 Removal of Smoke Taint

16.7 Wine Stabilisation and pH Adjustment by Electrodialysis

16.7.1 Tartrate Stabilisation

16.7.2 pH and Acidity Adjustment

16.8 Final Reflections

References

17 The Impact of Container and Closure Upon Wine Faults

17.1 Introduction

17.2 Glass Bottles. 17.2.1 Overview

17.2.2 A Brief History of Glass Bottles for Wine

17.2.3 The Impact of Bottle Size Upon Wine Development and Quality

17.2.4 The Impacts of Bottle Colour and Glass Thickness/Weight

17.3 Bottle Closures

17.3.1 Types of Closure

17.3.2 Dissolved Oxygen in Wine. 17.3.2.1 Sources of Dissolved Oxygen and Total Package Oxygen in Wine

17.3.2.2 Consequences of Oxygen Uptake During the Bottling Operation

17.3.2.3 Oxygen Transmission Rates (OTRs), Permeation, Migration, and Scalping. Permeation

Migration

Scalping

17.4 The Maintenance of Adequate Fee and Molecular SO2 in Bottled Wine. 17.4.1 The Adjustment of Free and Molecular SO2 at Bottling

17.4.2 Retention of Adequate Free Sulfur Dioxide in Bottle

17.4.3 The Influence of Closure Type Upon Reductive Characters

17.4.4 The Market for the Various Types of Closures

17.5 Cork Closures

17.5.1 A Brief History of Cork Closures

17.5.2 The Origin of Cork and Production of Cork Stoppers

17.5.3 The Cork Production Process

17.5.4 Natural Corks and Colmated Corks. 17.5.4.1 Grades of Natural Cork

17.5.4.2 Colmated Corks

17.6 Technical Corks and Agglomerated Corks

17.6.1 Micro‐agglomerated Corks

17.6.2 Twin Top, 1 + 1 and Sparkling Wine Other Technical Corks

17.6.3 Helix

17.6.4 ProCork

17.7 Diam Cork Closure. 17.7.1 History: From the Altec Disaster to Diam Success

17.7.2 The Technology of the Diam Closure

17.7.3 The Range of Diam Closures and OTRs

17.8 Synthetic Closures

17.8.1 Co‐extruded Closures

17.8.1.1 Nomacorc

17.8.2 Injection‐Moulded Closures

17.8.3 Flavour Scalping

17.9 Screw Caps

17.9.1 History

17.9.2 Screw Cap Liners

17.9.3 Post‐Bottling Reduction

17.9.4 Damage to Screw Caps

17.10 Vinolok

17.11 Some Advantages and Disadvantages of Various Closure Types

17.12 The Bottling Operation

17.13 PET Bottles

17.14 Cans

17.15 Bag‐in‐Box

17.15.1 History of Bag‐in‐Box

17.15.2 The Manufacture of the Bag

17.15.3 Filling Bag‐in‐Box Wines

17.16 Final Reflections

References

18 Best Practice for Fault and Flaw Prevention

18.1 The Wine Industry

18.2 HACCP

18.3 Standard Operating Procedures (SOPs)

18.4 Traceability

18.5 Winery Design

18.6 Cleaning and Sanitation

18.6.1 Winery Water

18.6.2 Cleaning Agents

18.6.3 Cleaning of Equipment

18.6.4 Suggested Sequence for Cleaning Equipment

18.6.5 Barrel Cleaning

18.7 Good Practice Winemaking Procedures to Avoid Spoilage, Faults, and Flaws

18.7.1 Harvesting

18.7.2 Transportation of Harvested Fruit

18.7.3 Sorting

18.7.4 De‐stemming, Crushing

18.7.5 Pressing (for White or Rosé Wines)

18.7.6 Yeast Nutrients

18.7.7 Oxygenating During Fermentation

18.7.8 Use of Inert Gasses and Topping of Containers

18.7.9 Bottling

18.8 The Use of Oenological Additions and Processing Aids. 18.8.1 Sulfur Dioxide. 18.8.1.1 Properties of Sulfur Dioxide

18.8.1.2 Total, Bound, Free, and Molecular Sulfur Dioxide

Free Sulfur Dioxide

18.8.1.3 Health and Legal Considerations

18.8.1.4 The Use of Sulfur Dioxide in Winemaking

Potassium Metabisulfite (PMBS)

Aqueous SO2

18.8.2 Dimethyl Dicarbonate (Velcorin)

18.8.3 Lysozyme

18.8.4 Chitosan

18.9 Routine Wine Analysis

18.10 Final, Final Reflections

References

Appendix A Levels of Free SO2 Required to Give 0.5, 0.625, and 0.8 mg/l of Molecular SO2 for Differing Wine pH Values

Further Reading. Easily Readable Books

Books with a More Scientific Approach

Glossary

Useful Websites

Index. a

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WILEY END USER LICENSE AGREEMENT

Отрывок из книги

Keith Grainger

Consultant in Wines and Wine Technology

.....

When wines are aged beyond their projected lifespan, or suffer premature decline (perhaps due to poor storage), all of the primary and many of the secondary aromas will be lost. Of the tertiary aromas that remain, some such as caramel, toffee or soaked fruitcake may be pleasant, but many will not. The smell of rotting cabbage, stale sweat, old trainers and burnt saucepans may come to the fore, and every hint of complexity will have been drained out, rendering the wine flawed.

The descriptors for the development of the nose may range from youthful to fully developed. When desirable aromatic compounds are waning and unwelcome characteristics of a tertiary nature, e.g. rotting vegetables, are assertive, the wine may be described as tired.

.....

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