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.