malolactic fermentation - a secondary fermentation in which bacteria convert tart malic acid into milder lactic acid and carbon dioxide. This process softens the wine and reduces acid. Most quality red wines undergo this malolactic fermentation, as well as whites seeking added smoothness and lower acidity. This process lessens a wine's fruitiness but adds complexity. No alcohol is produced by malolactic fermentation.
  Sonoma County Chardonnay