More accurately referred to as "malolactic conversion." A bacterial conversion occurring in most wines, this natural process converts sharper malic acid (the same acid found in green apples) into softer lactic acid (the same acid found in milk). Total acidity is reduced; the wines become softer, rounder and more complex. In addition, malolactic conversion stabilizes wines by preventing an undesirable fermentation in the bottle. Most red wines undergo malolactic conversion, but the practice is most frequently discussed in association with Chardonnay: When employed, ML results in rich, buttery whites; it's prevented when fresher, crisper styles are desired.