Malolactic Fermentation

We have discussed malolactic fermentation (MLF) several times while tasting white wines, Chardonnay in particular.  It changes both the acidity and the flavor profile of the wine.  Specifically, it "softens" the acidity by converting the tart malic acid naturally present in the wine to lactic acid and gives, to white wines, a buttery taste.  The vast majority of red wines also go through MLF and would taste harsh if they did not.  Since it is common practice and therefore not really a stylistic choice, it is rarely discussed in relation to red wines.  With white wines, the winemaker makes a concious decision whether or not to allow it to occur.  In warm climates where white wines need to retain as much acidity as possible, the winemaker may decide to prevent it.  Also, in cool climates where the crisp acidity is, in essence, the point of the wines made there, the MLF will be prevented- think Chablis or German Rieslings.  In cool climate regions that produce full bodied wines such as Burgundy's Cote d'Or, the MLF can give the wines added richness.  Sometimes, winemakers will allow it in a portion of the lots of wine they are making and prevent it in other lots, and then blend the lots together to gain the desired flavor profile.

For a more scientific explanation, click here

Or watch this winemaker explain the process...