Second Fermentation

by Staff Writer - K. Ash | June 14, 2012

A second fermentation is observed in wines that contain trace amounts of sugars left over from a stopped fermentation. The second fermentation occurs after bottling and converts the remaining sugars into alcohol, destroying the character of the wine in the process.

Many wines — white wines in particular — retain sweet characteristics. This is a desired effect and is controlled by the vintner prematurely stopping the fermentation process. With the fermentation process stopped and residual sugar being present in the wine, the vintner must take precautions to ensure that fermentation does not re-commence. After a wine has been bottled the vintner no longer has absolute control of the wine. If just one live yeast organism is present within the bottled wine, a second fermentation will occur. Symptoms of a second fermentation include cloudy wine and increased container pressure with the character of the wine being ultimately ruined. To prevent a second fermentation from destroying wine, modern aseptic bottling techniques along with filtration must be used. It is also important to note that a second fermentation is different from the secondary fermentation step found within the winemaking process. Secondary fermentation is a critical function that softens the acidity of the final wine.

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