Wine Fermentation

Fermentation Management Guide

I. Introduction
II. Factors Impacting Pre-Fermentation Flora

A. Vineyard Impacts on Flora

  • Varietal Factors
  • Site Factors
  • Seasonal Factors
  • Flora Management
  • Vine Nutrient Management
  • Vineyard Management Practices
  • Impact of Grape Maturity
  • The Role of Insects
  • Fungal Damage and Rots
  • Role of Animal Damage
  • Summary and Recommendations

B. Harvesting Conditions and Flora

  • Introduction
  • Fruit Damage
  • Cluster Sorting
  • Temperature
  • Material Other Than Grape
  • Summary and Recommendations

C. Grape, Juice and Must Processing Impacts on Flora

  • Introduction
  • Skin Contact Factors
  • Pre-Fermentation Processing
  • Clarification
  • Temperature Treatments
  • Enzymatic Treatments
  • Oxygen Exposure
  • Impact of Sulfite Addition
  • Summary and Recommendations
III. Fermentation Management Practices
  • Introduction

A. Inoculation Practices

  • Inoculated versus Uninoculated Fermentations
  • Indigenous Flora versus Commercial Preparations
  • Yeast Strains
  • Timing of Inoculation
  • Inoculation Levels

B. Sulfite Use

C. Impact of Winery Sanitation

D. Nutrient Additions

E. Timing of Nutrient Additions

F. Fermentation Monitoring

G. Temperature

H. pH

I. Oxygen

J. Summary and Recommendations

IV Tips for Successful Yeast Fermentation Management
Problem Fermentations

A. Introduction

  • Overview
  • Typical Fermentations

B. Fermentation Progression Problems: Types, Diagnosing and Correcting

  • Slow initiation of fermentation, rate becoming normal
  • Slow initiation of fermentation, fermentation sluggish throughout
  • Normal initiation of fermentation, rate becoming sluggish
  • Fermentation normal, abrupt stop
  • Restarting Arrested Fermentations:

C. Off-Character Formation

  • Introduction
  • Types of Fermentation-Driven Off-Characters
  • Prevention of Off-Character Production
  • Mitigation of Off-Characters