levains

Levains are a form of natural leaven used in breadmaking, especially in French and artisanal traditions. A levain (plural levains) is a culture of wild yeast and lactic acid bacteria living in a mixture of flour and water. The yeast consumes sugars to produce carbon dioxide, which leavens the dough, while the bacteria generate organic acids that contribute flavor and shelf life. Levains arise from the ambient microflora of flour and the baker’s environment and can be started from a portion of a previous levain or from a fresh mixture of flour and water inoculated with wild yeasts.

To keep a levain active, bakers refresh it at intervals by feeding with fresh flour and water, a process called feeding or refreshing. The hydration level (ratio of water to flour) affects texture and fermentation speed: stiff levains have lower hydration and tend to produce more acidity; liquid levains ferment more quickly and yield lighter textures. Levains are typically matured to a balance of acidity, aroma, and strength before being used to inoculate dough, often at 10–30 percent of dough weight, depending on the recipe and desired flavor.

Levains differ from commercial yeast in that they develop complex flavors through longer, slower fermentation and rely on a stable culture of wild yeasts and bacteria. They require regular maintenance and can be stored at room temperature for daily use or refrigerated to slow activity. The term levain is French for “leaven,” and in bakery practice it denotes both the culture and the portion used to ferment dough.