Surdegen

Surdegen, or the sourdough starter, is a stable culture used to leaven bread. It consists of a mix of flour and water that has been colonized by wild yeasts and lactic acid bacteria. Through ongoing fermentation, these microorganisms metabolize sugars, producing carbon dioxide that raises the dough and organic acids that contribute flavor and preserve the loaf.

Maintaining the surdegen requires regular feedings of fresh flour and water and occasional discarding of a portion of the culture. At room temperature the starter is usually fed daily; in cooler conditions it can be kept in the refrigerator and fed less often. Hydration level, the ratio of water to flour, influences both texture and taste, with common starters ranging from stiff to liquid.

In baking, surdegen replaces commercial yeast as the leavening agent. It develops flavor through extended fermentation and affects crumb structure and crumb softness. Doughs prepared with a mature starter typically require longer rising times but yield a more complex aroma and better shelf life.

Sourdough fermentation is an ancient technique used in many cultures. Today, surdegen remains popular among home bakers and artisanal producers for its distinctive character, though it demands planning and patience compared with quicker yeast-based methods.