Malolactic fermentation (MLF) is a secondary bacterial fermentation carried out in most red wines and some white and sparkling wines. It often occurs naturally after the completion of primary fermentation or can also be induced by inoculation with a selected bacterial strain.

How does malolactic fermentation start?

MLF involves bacteria instead of yeast, and it usually begins when primary fermentation is complete, around 0° Brix. Malolactic fermentation is conducted by Leuconostoc bacteria cultures. ... These bacteria convert malic acid, which is naturally present in fruits like grapes and apples, to lactic acid.

What causes malolactic fermentation?

Bacteria is responsible for releasing an impact compound called Diacetyl, which gives wine buttery/creamy aromas. Also called malo or MLF, malolactic fermentation is a process where tart malic acid in wine converts to softer, creamier lactic acid (the same acid found in milk).