What process is used to make sourdough rise?

The process used to make sourdough rise is natural fermentation. In sourdough bread, the leavening agent is a mixture of wild yeast and lactic acid bacteria that develop in the sourdough starter. This natural fermentation process works over time as the yeast ferments the sugars present in the dough, producing carbon dioxide gas and alcohol. The carbon dioxide gas gets trapped within the dough's gluten structure, causing it to expand and rise.

Natural fermentation is key to sourdough because it involves the complex interaction of various microorganisms, leading not just to leavening but also contributing to the unique flavor and texture inherent in sourdough bread. This is distinct from chemical leavening, which involves ingredients like baking powder or baking soda that react chemically to produce gas. Although yeast fermentation is a related concept, it does not encompass the broader microbial ecosystem present in a sourdough starter, which is essential for the unique characteristics of sourdough. Mechanical aeration, such as whisking or beating, is not relevant to the traditional sourdough process, as it does not create the natural rise inherent to this type of bread.