Secondary fermentation

Secondary fermentation meaning in wine

Secondary fermentation refers to two distinct winemaking processes, depending on regional terminology. Most commonly, it describes the continuation of alcoholic fermentation after transferring wine from its initial fermentation vessel to a secondary container, such as moving from stainless steel tanks to oak barrels. This transfer typically occurs when primary fermentation is nearly complete, allowing the wine to finish converting residual sugars while beginning maturation in the new environment. In Australian wine terminology, secondary fermentation specifically refers to malolactic fermentation (MLF), a separate biological process where lactic acid bacteria convert sharp malic acid into softer lactic acid, reducing acidity and creating a rounder mouthfeel. This process typically occurs at temperatures between 18-22°C and can take several weeks to months. MLF is particularly important for red wines and some white wines like Chardonnay, contributing to complexity and stability. The timing and control of secondary fermentation significantly impacts wine style, with winemakers choosing when to encourage or prevent MLF based on desired flavor profiles. Whether referring to vessel transfer or malolactic conversion, secondary fermentation represents a crucial stage in wine development, bridging primary fermentation and final maturation.