Secondary Fermentation

Secondary Fermentation

Secondary fermentation is a slower, second stage of fermentation that follows an initial primary fermentation, used to further develop flavor, aroma, and texture in beer, wine, and some breads.

In beer, it happens in a separate vessel, such as a conditioning tank or cask, and lets remaining yeast and suspended solids settle out while flavor develops, yielding a smoother, more balanced beer. In wine, it usually means malolactic fermentation, where bacteria convert sharper malic acid into softer lactic acid, softening texture and flavor. In sourdough bread, it refers to the final proof after shaping, when yeast and bacteria continue producing the compounds behind the bread's characteristic sourness.

Duration varies widely by product: beer may take weeks or months, sourdough only a few hours.