lecture 7: overview of white wine processing. reading assignment: chapter 5, pages 193-221
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Lecture 7:
Overview of White Wine Processing
Reading Assignment:
Chapter 5, pages 193-221
The Basic Steps of White Wine Production
1. Crushing, destemming
2. Pressing
3. Cold Settling/Racking
4. Fermentation
5. Racking
6. Finish of Fermentation
Principle White Wine Grape Varieties in California
• Thompson Seedless 60%
• Chardonnay 18.4%
• French Colombard 10%
• Chenin blanc 4.6%
• Sauvignon blanc 2.2%
Options for White Wine Production
• Style– Varietal or Blend– Premium or Picnic– Price/Volume
Options for White Wine Production: Style• Premium wine varieties:
– Chardonnay– Sauvignon blanc
• Dessert wine varieties:– White Riesling– Muscat– Gewürztraminer
• Picnic (Jug) wine varieties:– French Colombard– Chenin blanc– Sultana/Sultanina/Kismis (Thompson seedless)
Options for White Wine Production: Style
• Late harvest
• “Botrytized” styles– Grapes infected with mold– Mold growth impacts composition– Mold impacts yeast fermentation
Options for White Wine Production
• Style
• Residual Sugar
Options for White Wine Production:Residual Sugar
• Dry (0.2% RS)
• Semisweet (0.5-2% RS)
• Sweet (5-10% RS)
How to achieve desired residual sugar
• Arrest fermentation– Temperature– Ethanol addition: fortification
• Add juice concentrate
• Late harvest: natural arrest of fermentation
• Add sweet reserve
Options for White Wine Production
• Style
• Residual Sugar
• Carbonation
Options for White Wine Production: Carbonation
• None – still wine
• Lightly carbonated
• Heavily carbonated (Sparkling wines)
White Wine Processing: Goals
• Limit skin extraction
• Limit oxidation
• Limit volatile flavor/aroma loss
White Wine Processing: Variables
• Solids content
White Wine Solids
• High solids: – Better yeast and ML fermentation– Decrease fruity content due to esterases of solids– Increase phenolics/astringency
• Control of solid content:– Take free run– Settle/Rack at low temperature– Centrifugation
White Wine Processing: Variables
• Solids content
• Skin contact
Skin Contact
• Increase phenolics/astringency
• Impacts yeast fermentation products
• Impacts microbial flora
White Wine Processing: Variables
• Solids content
• Skin contact
• Pressing conditions
Pressing Conditions
• Higher pressure, higher solids content, harder to settle
• Warmer pressing, greater extraction
White Wine Processing: Variables
• Solids content
• Skin contact
• Pressing conditions
• Temperature
Temperature
• 12-16ºC
• Lower temperature, greater retention of aroma volatiles
White Wine Processing: Variables
• Solids content
• Skin contact
• Pressing conditions
• Temperature
• Oxygen exposure
Oxygen Exposure
• Can stimulate yeast
• Can lead to off-color (pink, brown) formation
• Can lead to development of oxidized characters
Preventing Oxidation of White Juices/Wines
• Use of chemical antioxidants: to block oxidation reactions
• High Temperature/Short Time (HTST): to inactivate oxidases
• Use of low temperature: to inhibit oxidases
• Carbon dioxide/Nitrogen blanketing: to eliminate oxygen
• Fining/Clarification: to remove oxidases
White Wine Processing: Variables
• Solids content
• Skin contact
• Pressing conditions
• Temperature
• Oxygen exposure
• Lees contact
Yeast Lees Contact
• Increases flavors/complexity
• Enhances mouth feel
White Wine Processing: Variables
• Solids content
• Skin contact
• Pressing conditions
• Temperature
• Oxygen exposure
• Lees contact
• Oak
Oak Options
• Fermentation in barrel– New– Used
• Kind of oak• Kind of toasting• Use of alternatives
– Chips– Staves
Rosé Wine Production:
There are two ways to produce a rosé wine:
1. As a blush wine of a red varietal
2. As a blend of a white wine with a red wine
Fermentation and Post-fermentation options for white wine production will be considered in later sections of the course. This concludes the section of the class on grape and must processing.