Malolactic fermentation

Malolactic fermentation meaning

Malolactic fermentation (MLF or “malo”) is a secondary fermentation process conducted by lactic acid bacteria, primarily Oenococcus oeni, that converts sharp-tasting malic acid into softer, creamier lactic acid while producing carbon dioxide as a byproduct. This bacterial conversion typically occurs after alcoholic fermentation and can happen spontaneously or be induced by inoculating with selected bacterial cultures. The process reduces wine acidity by approximately 1-3 g/L, creating a rounder mouthfeel and adding complexity through the production of compounds like diacetyl, which contributes buttery aromas. MLF is essential for most red wines, as it provides stability and softens harsh tannins, while its use in white wines varies by style—encouraged in full-bodied Chardonnays for richness but often prevented in crisp varieties like Sauvignon Blanc to preserve bright acidity. The fermentation typically occurs at temperatures between 18-22°C and can take several weeks to months. Winemakers monitor MLF completion through chromatography testing, ensuring no residual malic acid remains to prevent unwanted bacterial activity in bottle. This process significantly influences wine style, transforming austere, acidic wines into more approachable, complex beverages with enhanced textural appeal.