Enological Chemistry

Chapter 1. The Vine

1. Biological Cycles of the Vine

1.1. The Growth Cycle

1.2. The Reproductive Cycle

2. Morphology of the Grape Clusters

2.1. The Stems or Stalk

2.2. The Grape

3. Chemical Composition of the Grapes

3.1. Composition of the Stalk

3.2. Composition of the Seeds

3.3. Composition of the Skin

3.4. Composition of the Pulp

3.5. Composition of the Must

Chapter 2. Composition of Grape Must

1. Grape Must

2. Chemical Families Present in Must

2.1. Sugars

2.2. Organic Acids

2.3. Nitrogen Compounds

2.4. Minerals

2.5. Polyphenols

2.6. Vitamins

2.7. Aromatic Compounds

Chapter 3. Must Aromas

1. Introduction

2. Terpenes

2.1. Chemical Description

2.2. Biosynthesis

2.3. Odorant Characteristics

2.4. Distribution of Terpenes in the Grape: Free and Bound Terpenes

2.5. Terpene Profiles During Grape Ripening

3. Carotenoids

3.1. C13-Norisoprenoid Derivatives

4. Pyrazines

5. Substances Derived From Pre-fermentation Treatments

5.1. Synthesis

6. Substances Released During Fermentation: Mercaptans

7. Importance of Volatile Compounds in Aroma

Chapter 4. Composition of Wine

1. The Transformation of Must Into Wine

1.1. Glyceropyruvic Fermentation

2. Alcoholic Fermentation and Composition of Wine

2.1. Sugars

2.2. Acids

2.3. Polyphenols

2.4. Mineral Substances

2.5. Nitrogen Compounds

2.6. Vitamins

2.7. Volatile Compounds

Chapter 5. Polyphenols

1. Introduction

2. Non-flavonoid Phenols

2.1. Phenolic Acids

2.2. Stilbenes

3. Flavonoid Phenols

3.1. Flavonols

3.2. Dihydroflavonols or Flavanonols

3.3. Flavanols

3.4. Tannins

3.5. Anthocyans, Anthocyanidins, and Anthocyanins

4. Profile of Tannins and Anthocyanins During Ripening

4.1. Phenolic Ripeness

5. Extraction of Phenolic Compounds During Vinification

5.1. Benzoic Acids and Flavonols

5.2. Anthocyans and Tannins

6. Vinification Strategies and Polyphenol Content

7. Modification of Phenolic Compounds During Vinification

7.1. Enzyme Activity

7.2. Chemical Phenomena

8. Biosynthesis of Phenolic Compounds

8.1. Biosynthesis of Simple Phenols

8.2. Biosynthesis of Flavonoid Phenols

Chapter 6. Sugars: Structure and Classification

1. Introduction

2. Structure of Carbohydrates

2.1. Cyclization of Carbohydrates: Haworth Projection

2.2. Monosaccharides of Interest in Winemaking

3. The Glycosidic Bond: Polymerization

3.1. Disaccharides and Trisaccharides

4. Polysaccharides

4.1. Polysaccharides in the Grape Berry Cell Walls

4.2. Polysaccharides From Fungi and Yeast

5. Glycosides

6. The Importance of Glycosides in Winemaking

Chapter 7. Sugars in Must

1. Introduction

2. Profile of Fermentable Hexoses

3. Physical Properties of Glucose and Fructose

3.1. Optical Rotatory Power

3.2. Relationship Between Optical Rotatory Power and Sugar Composition

3.3. Polarimetry in Winemaking

3.4. The Sweetening Power of Sugars

4. Chemical Properties of Sugars

4.1. Oxidation in the Presence of Luff-Schoorl Reagent

4.2. Enzymatic Oxidation

4.3. Nonenzymatic Oxidation Reaction

4.4 Combination With Sulfite

5. Nonfermentable Monosaccharides and Derivatives

5.1. Nonfermentable Monosaccharides

5.2. Nonfermentable Derivatives

Chapter 8. Carboxylic Acids: Structure and Properties

1. Introduction

2. The Carboxyl Group: Basic Concepts

3. Monocarboxylic Acids

3.1. Physical Properties

3.2. Chemical Properties

3.3. Factors That Influence Acidity

4. Dicarboxylic Acids

4.1. Physical Properties

4.2. Chemical Properties

5. Hydroxy Acids

5.1. Physical Properties

5.2. Chemical Properties

6. Keto Acids

Chapter 9. Grape Acids

1. Introduction

2. Tartaric Acid

2.1. Chemical and Physical Properties

3. Malic Acid

3.1. Chemical and Physical Properties

4. Citric Acid

4.1. Chemical and Physical Properties

5. Changes in Acid Content and Acidity During Grape Ripening

5.1. Forms of Expressing the Acid Content of Musts

5.2. Changes in Malic Acid Content During Grape Ripening

5.3. Changes in Tartaric Acid Content During Grape Ripening

6. Other Grape Acids

6.1. Gluconic Acid: A Special case

7. Analysis of Acids

7.1. Measurement of Total Acid Content

7.2. Measurement of Specific Acids

Chapter 10. The Relationship Between Must Composition and Quality

1. The Harvest

1.1. Long-term Predictions

1.2. Prediction Based on Monitoring of Ripeness

2. Phenolic Compounds and Sampling

3. Ripeness

3.1. Measures of Ripeness

3.2. Other Variables Used to Define the Optimal Time for Harvesting

4. Factors Affecting the Quality and Ripeness of the Grape

4.1. Invariant Factors

4.2. Climatological Factors

4.3. Modifiable Factors

4.4. Accidental Factors

5. Corrections

5.1. Correction of Sugar Content

5.2. Correction of Acidity

Chapter 11. The Transformation of Must Into Wine

1. Introduction

2. The Pasteur and Crabtree Effects

3. Glycolysis

4. Alcoholic Fermentation

5. Glyceropyruvic Fermentation

5.1. Secondary Products of Glyceropyruvic Fermentation

5.2. Mass Balance in Glyceropyruvic Fermentation

6. Changes in Grape Acids During Fermentation

7. Factors Affecting Alcoholic Fermentation

7.1. Physical Factors

7.2. Biological Factors

7.3. Chemical Factors

8. Formation of Lactic Acid by Lactic Acid Bacteria

8.1. Lactic Acid Fermentation of Hexoses

8.2. Lactic Acid Fermentation of Hexoses

8.3. Malolactic Fermentation

9. Maloalcoholic Fermentation

10. Residual Sugars and Type of Wine

Chapter 12. Nitrogen Compounds

1. Introduction

2. Total Nitrogen and Assimilable Nitrogen

3. Nitrogen Compounds in Grapes and Must

3.1. Total Nitrogen

3.2. Ammonium

3.3. Amino Acids

3.4. Peptides and Proteins

4. Changes in Nitrogen Content During Grape Ripening

5. Changes in Nitrogen Content During Fermentation

5.1. Ammonium

5.2. Amino Acids

6. Proteins

6.1. General Characteristics

6.2. Factors that Influence the Protein Content of Musts

6.3. Changes in Protein Content During Fermentation

7. Other Nitrogen Compounds

7.1. Urea and Ethyl Carbamate

7.2. Biogenic Amines

Chapter 13. Acid-Base Equilibria in Wine

1. Introduction

2. Law of Mass Action

2.1. Ionic Product of Water

2.2. pH

3. Dissociation Constants: Strength of Acids and Bases

3.1. Degree of Dissociation

4. Activity and Thermodynamic Constant

4.1. Debye-Hückel Theory

4.2. Calculating Activity

5. Mixed and Thermodynamic Dissociation Constants

6. Dissociation State of Organic Acids

6.1. Monoprotic Acids

6.2. Diprotic Acids

7. Changes in Degree of Dissociation and Molar Fraction With pH

8. Proportion of Neutralized Acids in Wine

Chapter 14. Buffering Capacity of Wines

1. Introduction

2. Buffering Capacity of Weak Acid Solutions

3. Buffering Capacity of Wine

4. Effect of Malolactic and Maloalcoholic Fermentation on Acid-Base Equilibrium of Wine

4.1. Malolactic Fermentation

4.2. Maloalcoholic Fermentation

5. Dry Extract Determined by Densitometry

6. Relationship Between Total and Titratable Acidity

7. Acidity and Organoleptic Characteristics

7.1. Flavor

7.2. Aroma

7.3. Color (Clarity and Brilliance)

7.4. Turbidity

8. Correction of Acidity

8.1. Calculating the Acid Dissociation Constant of Wine

8.2. Deacidification

8.3. Acidification

9. Final considerations

Chapter 15. Precipitation Equilibria in Wine

1. Introduction

2. Tartrate Stability

3. Factors Affecting Alcoholic Fermentation

3.1. The Uncommon Ion Effect

3.2. The Common Ion Effect

4. Factors Affecting Alcoholic Fermentation

4.1. pH

4.2. Ethanol

4.3. Temperature

5. Potassium Bitartrate Stability

5.1. Potassium Bitartrate Stability

5.2. Relative Saturation

5.3. Calculating the Amount of Potassium Bitartrate to Eliminate From a Wine

5.4. Protection Against Calcium Tartrate Precipitation

6. Protective Effects of Precipitation

6.1. Protection Against Potassium Bitartrate Precipitation

6.2. Protection Against Calcium Tartrate Precipitation

7. Appendix

Chapter 16. Changes in Acidity After Fermentation

1. Introduction

2. Physical Treatments for Tartrate Stabilization of Wine

2.1. Cold Treatment

2.2. Contact Method

2.3. Pseudo-Contact Method

2.4. Treatment With Ion-Exchange Resins

2.5. Treatment Using Membranes: Electrodialysis

2.6. Effectiveness of Physical Treatments for Tartrate Stabilization

3. Chemical Treatments for Tartrate Stabilization

3.1. Metatartaric Acid

3.2. Sodium Carboxymethyl Cellulose

3.3. Mannoproteins

4. Assessment of Treatment Efficacy

4.1. Cold-Storage Test

4.3. Tests Based on the Contact Method

4.2. Tests Based on the Saturation Temperature

4.3. Tests Based on Analytical Results

5. Spoilage Processes That Affect Acids

5.1. Pricked Wine

5.2. Tourne

5.3. Production of Bitterness by Fermentation of Glycerol

5.4. Degradation of Citric and Sorbic Acid

Chapter 17. Redox Phenomena in Must and Wine

1. Introduction

2. Redox Reactions: Basic Concepts

2.1. Oxidation Number

3. Redox Potential

3.1. Nernst Equation

4. Measuring Redox Potential in Wine

4.1. Changes in Redox Potential During the Making of Wine

5. Oxygen and Winemaking

5.1. Measuring Dissolved Oxygen: The Clark Electrode

5.2. Influence of Certain Operations on Oxygen Content

5.3. The Presence of Oxygen in Wine: Technological Implications

6. Oxidation of Polyphenols in Must and Wine

6.1. Enzymatic Oxidation

6.2. Chemical Oxidation

6.3. Browning of Must and Wine

6.4. Technical Considerations

Chapter 18. The Colloidal State

1. Introduction to Dispersed Systems

2. General Characteristics of Colloids

3. Classification of Colloids

4. Approaches to the Analysis of Sols and Gels

4.1. Thixotropy

4.2. Peptization and Flocculation

4.3. Syneresis

5. Properties of Colloids

5.1. Optical Properties

5.2. Mechanical Properties

5.3. Adsorption Properties

5.4. Electrical Properties

5.5. Other Properties

6. Sols

6.1. Hydrophobic Sols

6.2. Hydrophilic Sols

6.3. Mechanisms of Electrical Charge Formation

7. Stability of Sols

7.1. Stability and Flocculation of Hydrophobic Sols

7.2. Stability of Hydrophilic Sols

8. Gels

9. Foams

Chapter 19. Wine Colloids

1. Introduction

2. Isolation and Classification of Colloids in Wine

2.1. Colloidal Carbohydrates

2.2. Colloidal Coloring Matter

2.3. Colloidal Proteins

3. Natural Clarification and Stabilization

4. Clarification With Proteins: Fining

4.1. Gelatin

4.2. Casein

4.3. Albumin

4.4. Fish Glue

4.5. Factors Which Affect Fining

4.6. Overfining

5. The Polyphenol-Protein Complex

5.1. Characteristics of Fining Proteins

5.2. Characteristics of Polyphenols

5.3. Factors That Influence the Phenol-Protein Interaction

6. Protein Casse

6.1. Clarity and Protein Stability

6.2. Influence of Aging on Lees on Protein Stability

7. Clarification With Bentonite

7.1. Structure

7.2. Physical and Chemical Characteristics

7.3. Types of Bentonite

7.4. Use in Must

7.5. Use in Wine

7.6. Action on Iron and Copper

7.7. Alternatives to the Use of Bentonite

8. Clarification With Colloidal Silica

9. Other Clarifying Agents

9.1. Vinylpyrrolidone Polymers

9.2. Alginates

9.3. Tannins

10. Protective Colloids

10.1. Gum Arabic

Chapter 20. Inorganic Material and Metal Casse

1. Introduction

2. Anions

3. Cations

4. Heavy Metals

5. Metal Casse

5.1. Ferric Casse

5.2. Copper Casse

6. Treatments to Prevent Ferric Casse

6.1. Treatment With Potassium Ferrocyanide

6.2. Treatment With Calcium Phytate

6.3. Treatment With Citric Acid

6.4. Treatment With Other Chelating Agents

6.5. Treatment With Ascorbic Acid

7. Treatments to Prevent Copper Casse

Chapter 21. Chemical Aging

1. Introduction: Aging and Storage

2. Aging in Oak

2.1. Types of Oak

3. Compounds Contributed to Wine by Wood

3.1. Volatile Compounds

3.2. Nonvolatile Compounds

4. Influence of Oxygen on Aging

5. Factors That Influence the Composition of Wood

5.1.Type of Oak

5.2. Drying System

5.3. Degree of Toasting

5.4. Number of Uses

Chapter 22. Aging

1. Introduction

2. Effect on Volatile Compounds

2.1. Esters

2.2. Aldehydes and Alcohols

2.3. Monoterpene Compounds

2.4. Norisoprenoid Compounds (C13)

2.5. Volatile Phenolic Compounds

2.6. Sulfur Compounds

3. Effect on Nonvolatile Phenolic Compounds

Chapter 23. Biological Aging

1. Introduction

2. Biological Aging: The Process

3. Changes Induced by Flor Yeasts

3.1. Ethanol

3.2. Glycerol

3.3. Acetaldehyde

3.4. Nitrogen Compounds

3.5. Organic Acids

3.6. Higher Alcohols and Esters

3.7. Lactones

3.8. Polyphenols

4. Factors Affecting Alcoholic Fermentation

4.1. Yeast Species or Race

4.2. Composition of Wine

4.3. Physical and Environmental Conditions of the Cellar