Ever wonder what gives Chardonnay that special buttery taste? The short answer is bacteria.

The conversion of malic acid to lactic acid and carbon dioxide is known as malolactic fermentation. This transformation occurs after the wine has been fermented and is activated by the addition of bacteria to the wine. This can also happen while the wine is aging in oak barrels.

Most people don’t realize that malolactic fermentation is used in almost all red wines to help lower acidity and mellow the wine. This method is not used in white wines that are noted for their aromatic qualities, or acidity, such as Sauvignon Blanc or Riesling.

To limit the butter taste but still give the wine a rounder, richer flavor, the winemaker can use malolactic fermentation on a portion of the finished wine that is then blended with the rest of the wine for bottling.