Primary Fermentation - Wine - Lecture Slides, Slides of Winemaking

Download Primary Fermentation - Wine - Lecture Slides and more Slides Winemaking in PDF only on Docsity!

Primary Fermentation

GrapeMaturity Pre-Ferm 1°^ 2°^ Aging^ Wine Stabilization^ Bottling

Harvest (pH, TA, Brix, MOG)^ Yeast Inoculation MLB Inoculation^ Add Molecular SO

2

Sugar Decline Malic Decline VA and FSO

2 Big-3^ DO

Master Blend Completed Stabilization Complete

TIME

Clean Winemaking Stage Diagram

Created by Bryan Avila : 2008

Grape Notes

Following veraison

Grape Maturity Monotoring Stage

QC

Milestones

Gates Stylistic^ TempNutrients RS-Enz Mal-Enz (^) Stylistic Stable

Bottled Wine

SO2/BP

Time (Not to Scale)

Introduction

• The goal of fermentation is to convert sugar into ethanol with a minimum of undesired by- products
• Optimize fruit character, mouthfeel and tastes
• Theoretically 180 grams of sugar will convert to 92 grams of ethanol, 51% of weight.
• About 5% of sugar goes to other metabolic by- products that can contribute the wine’s complexity

Introduction

• Approximately 1.75 Brix = 1% Alcohol (v/v)
  • 1/1.75 = 0.57 (aka conversion rate)
  • Potential Alc = approx 0.57 x Brix
• Conversion rate varies depending on amount of non-sugar solids
• Less ripe fruit has a higher degree of non- sugar solids (They are very high in acids)
• Ethanol yield also depends on fermentation temp  EtOH losses also come from volatilization

Wine Yeast

• Louie Pasteur found that winemaking was performed by yeast, not magic.
• Development of microbiological practices and experimentation of with pure yeast cultures have led to cleaner fermentations
• Inoculations with cultured yeast out compete wild microbes by sheer numbers and through breeding

Cultured Wine Yeast Attributes

• Tolerance to vinification conditions
  • Alcohol, SO2, Temperature
• Different By-products
  • Less Sulfides, VA, more esters, glycerol, etc.
• Ability to ferment to dryness
• Flocculation leading to better formation of lees
• Fermentation kinetics – rate of fermentation

Killer Yeast

• Mutated strain of yeast that releases toxins harmful to it’s own strain
• Toxin is a protein
• Can result in stuck fermentation

Fermentation

• Microbial cell growth follow a similar growth curve

Inoculation

• Performed when a pure culture is added to wine
• Liquid vs. active dry
• Inoculums are added to out compete wild strains through breeding and pure numbers (10^6)
• Rehydrating yeast goals
  • Rehydrate yeast being careful not to grind yeast cells by harsh stirring
  • Allow for temperature acclimatization
  • Allow starter to become metabolically active

White Wine Fermentation

Common problems during Fermentation

• Ethyl Acetate – spoilage microbes, Wild yeast
• Sulfides – Nutrient deficiency is common but only one of many origins
• Sluggish/stuck fermentation – nutrition problems, extreme temp, spoilage microbes(toxins), ethanol toxicity

Ethanol Toxicity

Fermentation Tanks

What’s happening in the fermenter?

Fermentation Monitoring Temperature Control Gas Venting

Sanitary Design

Solids Handling

Engineering & Construction

• Conversion of grape sugars to ethanol
• Fermentation produces heat
• Yeast produce carbon dioxide gas
• Yeast are competing against other wild microorganisms
• Tanks hold several tons of must or juice
• Color and other phenolics are being extracted from skins in red fermentation