Before the discovery and use of commercial yeast, people used alternative methods to make bread rise. Here are a few historical methods:
Natural fermentation: Before the commercial production of yeast, bread was often leavened through natural fermentation. This process relied on capturing wild yeasts present in the environment. The baker would create a mixture of flour and water and let it sit exposed to the air. Over time, wild yeasts from the environment would colonize the mixture, fermenting the dough and causing it to rise. This method required patience and consistency, as the process could take several hours or even days.
Sour dough: Sour dough is a type of bread made with a fermented mixture of flour and water. Instead of relying on commercial yeast, sour dough utilizes naturally occurring wild yeasts and lactic acid bacteria present in the environment. The baker creates a starter or "mother dough" by mixing flour and water and allowing it to ferment over several days. This starter is then used as a leavening agent in bread recipes, providing the necessary rise and flavor. The starter can be maintained over a long period by regularly feeding it with flour and water to keep the fermentation process going.
Barm: Barm is another traditional method of leavening bread that predates the use of commercial yeast. Barm is a frothy, fermented liquid obtained from the process of brewing beer or ale. The yeast present in the brewing process would naturally multiply and create a bubbly liquid, which could then be used as a leavening agent for bread. Bakers would collect barm from local breweries and incorporate it into their bread recipes to achieve a rise.
It's important to note that these methods required careful observation and skill to maintain the proper fermentation conditions. The introduction of commercial yeast in the 19th century made bread production more reliable, consistent, and less time-consuming.