Term for the conversion of malic acid into the milder-tasting lactic acid (Latin malum = apple, lac = milk), which plays an alternative role in the production of fruit juice, wine and sparkling wine(champagne, sparkling wine). The process is also called biological acid degradation (BSA), bacterial malic acid degradation, microbial acid degradation or apple-lactic acid fermentation, because carbon dioxide is also released. However, it is not actually a real fermentation, but was once thought to be. Around 1890, Dr. Hermann Müller-Thurgau (1850-1927), who was working in Geisenheim at the time, correctly suspected bacteria as the cause. Dr. Wenzel Seifert (1862-1942) was then able to identify the acid-degrading bacterium in 1903 at the Klosterneuburger Weinbauinstitut and named it "Micrococcus malolacticus".
It is a natural process that can take 10 to 40 days. It is started spontaneously from about 16 °Celsius by bacteria (Oenococcus oeni) that are already present or have been added. However, it can also be started by stirring from lees, by blending with a wine already in the BSA process or (which...
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