Reducing acidity in wine

Malolactic fermentation is the second fermentation in wine, following alcoholic fermentation. It was discovered in the 1960s. Unlike alcoholic fermentation, it is not triggered automatically, but rather by bacteria that transform malic acid into lactic acid, while releasing carbon dioxide.

Malolactic fermentation is generally used for red wines. It makes the wine more supple and stable. In concrete terms, it reduces the acidity of wine by transforming a strong acid (malic acid) into a weak acid (lactic acid).

It can also be sought for champagnes to prevent it from occurring during foaming or ageing, which would cause difficulties during riddling.

How to control malolactic fermentation?

Mastering malolactic fermentation is no simple matter. This requires time, experience, resources and a good knowledge of the basics of microbiology. Malolactic fermentation can be induced in two ways:

• Incense. Yeast is added to precipitate malolactic fermentation.
• Co-inoculation. It accelerates malolactic fermentation by co-inoculating a must with yeast and malolactic ferments.

Malolactic fermentation conditions

For new wines, malolactic fermentation takes place in November, a few weeks after alcoholic fermentation. For bacteria to thrive, the temperature must be maintained between 20° and 23°.

After malolactic fermentation, the wine must be racked and sulfited to separate it from its lees, which contain bacteria that are now useless and dangerous. They can attack the wine’s residual sugars and citric acid, turning the wine into vinegar.