Yeast converts the sugars in grape juice to alcohol.
Yeast fermentation produces the alcohol in wine and determines its dryness or sweetness. The longer yeast breaks down the grapes' sugars--fermentation--the higher the alcohol content. The more sugar broken down by the yeast, the dryer the wine.
White wine
Crushed grapes are mixed with yeast and transferred to a tank to ferment.
Most white wines come from red-skinned grapes, so the skins of the crushed grapes must be removed before the juice is transferred to tanks and mixed with yeasts for fermentation.
Champagne and sparkling wine
A second yeast fermentation produces the carbon dioxide in Champagne and sparkling wines.
An alcohol-resistant yeast and sugar are added to sparkling wines when bottled, causing a second fermentation. The byproduct of this fermentation is carbon dioxide, which is trapped in the tightly corked bottle.
Alcohol content
A ripe grape contains more sugar, yielding a high content of alcohol in the wine.
The sugar content increases as a grape ripens. Therefore, yeasts have to break down during fermentation, resulting in a high-alcohol wine.
Sweet versus dry
The sweetness or dryness of a wine depends upon the amount of sugar yeast breaks down.
A sweet wine results when fermentation ceases before all the natural sugars in the grapes are broken down by yeast. A wine with 3 percent or greater residual sugar is considered a sweet wine. Dry wines typically contain less than 2 percent residual sugar, since most of it was digested in fermentation.
Fruitiness
Fruitiness is most apparent in a young wine.
Fruitiness can characterize either a sweet or dry wine and largely depends on the age of the finished wine. A young wine, aged only a few months before bottling, is more likely to exemplify fruit flavors.
Tags: more sugar, sweet wine, alcohol wine, breaks down, broken down