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Russ Briley Wine-ing: It has how much alcohol?

It all depends on how long grapes stay on the vine

Posted: February 24, 2012 6:00 a.m.
Updated: February 24, 2012 6:00 a.m.
Russ Briley Russ Briley
Russ Briley

Ever wonder why the alcohol content in wine varies so much from wine to wine? This is due to many things, but the major factor is when the grapes are harvested.

The longer the grape stays on the vine after it ripens, the more sugar is in the grape. More sugar in the grape will result in more alcohol.

When the grapes start to ripen, a small sample is taken from the vineyard and the sugar level is measured. An instrument called a refractometer measures this. This measurement is called "brix," which equals the percentage of sugar in a liquid. A measurement of 24 brix means the juice sample was 24 percent sugar.

When the grapes reach a desired brix level, they are harvested. After crushing red wine grapes, and crushing and pressing white wine grapes, the juice is ready for fermentation.

Yeasts are introduced and fermentation starts. The sugar is converted into alcohol and carbon dioxide during fermentation. In many cases, the wine is fermented "dry," which means all the sugar is converted into alcohol and carbon dioxide.

The conversion of brix to alcohol occurs at a ratio of about 0.55. For example, with a 24 brix level, you would multiply this by 0.55 to arrive at an alcohol content of about 13.2 percent. Grapes harvested at 30 brix could give you an alcohol content of 16.5 percent.

Some wines, such as Riesling and gewürztraminer, are not fermented dry, to retain some sweetness to enhance the flavor of the fruit. To keep these wines sweeter than dry whites, you need to stop the fermentation process before all the sugar is depleted.

Stopping fermentation is usually done in one of two ways. You can add a little sulfur dioxide, which kills the yeasts, or you can lower the temperature of the wine, which will also stop fermentation and leave the wine with some residual sugar. This results in wines with lower alcohol content.

Some states and countries allow you to add sugar before or during fermentation. This is called chaptalization. This allows the wine to have both the sugar and higher alcohol, but the procedure is not allowed in California.

Quick quiz
As I stated, chaptalization - the adding of sugar to wine - is not allowed in California. It is, however, OK in many other countries. In which of these major wine-producing countries is chaptalization never allowed?

a. France
b. Italy
c. Germany
d. New Zealand

The answer is b., Italy. Chaptalization is allowed in France, under strict guidelines. It is also allowed in certain regions of Germany and in New Zealand.
© Ventura County Star

As well as writing a wine column for the Ventura County Star, Russ Briley, long time Santa Clarita Valley resident, recently completed the Wine Studies program at COC. Russ and his wife Nancy also own Nuggucciet Cellars, where they produce small lots of Pinot Noir wine. Visit Email Briley at


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