Irene’s Reviews > On Food and Cooking: The Science and Lore of the Kitchen > Status Update

Winemakers sometimes allow a second bacterial fermentation in the new wine. The baterium L oenos consumes the wine's malic acid and converts it into lactic acid, less strong and sour. This "malolactic" fermentation reduces the tartness of the wine and produces buttery diacetyl. (A relative of this bacterium contributes the same compound to cultured butter itself!) - On Food and Cooking