malolattica

Malolattica, also known as malolactic fermentation (MLF), is a secondary biological process in winemaking in which lactic acid bacteria convert malic acid into lactic acid and carbon dioxide. By reducing malic acid, MLF lowers acidity and can soften the wine’s mouthfeel, contributing to a rounder, creamier texture. In addition, certain lactic acid bacteria can produce diacetyl, a volatile compound that imparts buttery or butterscotch notes, which is desirable in some styles and unwanted in others.

The primary organism responsible is Oenococcus oeni, though other lactic acid bacteria such as Lactobacillus, Leuconostoc, and Pediococcus can perform malolactic conversion under suitable conditions. Because spontaneous MLF can be unpredictable, many producers use selected starter cultures to promote consistent results and reduce the risk of spoilage or off-flavors.

The process is typically triggered after alcoholic fermentation or during maturation, when sugars are low enough and malic acid is present. It requires appropriate temperature, pH, and oxygen levels; common conditions are moderate temperatures around 18-22°C and pH around 3-4. The addition of sulfur dioxide or high alcohol can inhibit MLF. In many wines, MLF is allowed to proceed to completion, while in others it is halted or driven to a desired partial degree to preserve acidity.

Winemakers consider MLF for acidity management, microbial stability, and style influence; it is especially common in many white wines (such as Chardonnay) and some reds, and it can be adjusted or prevented depending on the desired wine profile.