surde

Surde, commonly known as sourdough, is a natural leavening culture used to bake bread. It consists of a living mixture of flour and water that becomes inhabited by wild yeasts and lactic acid bacteria. The fermentation raises dough and yields complex flavors, aromas, and a chewy texture.

The rise comes from carbon dioxide produced by yeasts, while lactic acid bacteria generate organic acids that give a mild tang and help preserve the bread. The balance between rise and sourness depends on factors such as hydration, flour type, and ambient temperature. Different starters and feeds create distinct flavors.

Maintenance of a surde involves regular feedings with fresh flour and water. The starter can be kept at room temperature for active use or refrigerated between bakes. Portions are often discarded during feeding to keep the culture healthy and active. Hydration levels commonly hover around 100 percent (equal weights of flour and water), though many bakers vary this to influence texture and acidity.

In baking, doughs made with surde benefit from longer fermentation, which enhances flavor, aroma, and crumb structure. Regional varieties exist, with some starters producing characteristic tangs. San Francisco sourdough, for example, is famed for its pronounced acidity due to specific bacterial strains.

History and culture: Sourdough has ancient origins and was the standard leavening method before the advent of commercial yeast. It remains popular among artisan bakers for its flavor, texture, and the resilience of long fermentation. Safety and care-wise, a well-maintained surde is safe and resilient when handled with clean equipment and proper feeding.