Malolactic fermentation is the secondary fermentation that some winemakers use to turn malic acid into lactic acid. This is done by the introduction of malolactic bacteria into the wine. Wines with malolactic fermentation sometimes have a noticable creaminess and buttery note.
Acidity
Acidity in wine is the level of acid that the wine contains. Wines with more acid in them taste more tart or sour.