Malolactic Fermentation

Posted on March 10, 2017

Author: Lamar Engel

Date: 4/20/2015

The conversion of malic acid to lactic acid through the action of lactic bacteria, a process often referred to as ‘malo’, ‘ML’ or ‘MLF’. The term ‘secondary fermentation’ is also used, although it is not technically a fermentation as yeast is not involved. Malic acid is much stronger than lactic acid, so wines that undergo this process are softer as a result. Most reds go through this process and has often been the standard process for most chardonnays up until recently where style has played a part. The byproducts of malolactic fermentation include carbon dioxide and diacetyl, a compound that contributes to the buttery aroma in the wine. Sometimes malolactic fermentation will occur simultaneously with alcoholic fermentation but more commonly are done after the first fermentation process as finished. Many traditional winemakers prefer to let it occur naturally while other will induce it by adding cultured lactic bacteria.