Malic acid

A natural acid found in sour apples and other fruits. In winemaking, when certain bacteria convert malic acid to Lactic Acid (which is much less strong and sour), a process called malolactic fermentation occurs. This reduces the wine's tartness, adds complexity to the flavor and sometimes contributes a slight sparkle. Malic acid is used as an acidulant as well as a flavoring agent in the processing of some foods.