Sourdough
Sourdough is a type of bread and various baked goods that are naturally leavened, primarily using a mixture of fermented flour and water. This fermentation process relies on wild yeast and lactic acid bacteria (LAB), which contribute to the bread's distinctive tangy flavor. Historically, sourdough has been used for thousands of years, with evidence of its use found in ancient Egyptian tombs. Before the development of commercial yeast, sourdough was the primary method for leavening bread.
The unique characteristics and flavor profile of sourdough depend on the specific species of yeast and bacteria present in the starter, also known as the sponge or mother. This starter can be cultivated by mixing flour and water and allowing it to ferment at room temperature, where it captures wild yeast and bacteria from the environment. Maintaining a sourdough starter involves regular feeding and refreshing, which ensures a steady growth of microorganisms.
Sourdough has cultural significance, having been a staple for pioneers and prospectors in the American West during historical gold rushes. The practice of sharing sourdough starters among neighbors fosters community connections and tradition, as these sponges can be passed down through generations. Overall, sourdough represents not only a unique culinary technique but also a rich cultural heritage.
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Sourdough
Sourdough is bread and other goods that is naturally leavened using a mixture of fermented flour and water. This mixture may be created using wild yeast or commercial yeast and can be used to make bread, pancakes, cakes, and other foods. Goods made with this mixture have a tangy taste from lactic acid bacteria (LAB) that gives sourdough its name.
People have made sourdough for thousands of years. Before development of commercial yeast, it was the only way to leaven bread. Yeasts, LAB, and acetic acid bacteria (AAB) produce CO2 bubbles that give breads and cakes an airy texture. Without a leavening agent such as yeast or baking powder, bread is flat like matzo and tortillas.
Overview
Sourdough starter, also called the sponge or mother, has been used to leaven bread since prehistory. Loaves and starters have been found in Egyptian tombs and other sites. The characteristics of the starters and baked goods are determined by the species of yeast and bacteria they contain. The amount of LAB in the dough determines how tangy its flavor will be.
Sourdough was commonly used in the American West and by prospectors seeking their fortunes during gold rushes. A small amount of dry starter could be wrapped in a bit of cloth or leather to keep for a long journey, then mixed with water and flour to reactivate it. A small piece of fresh raw dough could also be wrapped and saved for baking in the next day or so. A jar of sponge has traditionally been given to a neighbor with a baked good produced from the starter; sponges are also handed down through generations.
Sourdough can be cultured by simply combining water and flour and leaving it semi-covered at room temperature while feeding it over the course of several days. This allows wild yeast and bacteria from the air to begin growing. Using starter involves measuring out the quantity required for a recipe while retaining a portion. The reserved portion must be fed—provided with the needed flour and water and possibly sugar to keep the microorganisms alive. It can be refrigerated to nearly stop growth and frozen to halt growth. If it is used regularly, maintenance involves continuing to feed the reserved starter. If it is not used or frozen, a portion will have to be removed and discarded occasionally so the microorganisms can be fed to keep them alive. A healthy and vigorous starter will be visibly bubbly as gas is produced.
Refrigerated starter will be dormant but does not completely stop growing. One must pour half of it away twenty-four hours before one wishes to use it and feed the reserved sponge. This process of reactivating the yeast is called refreshing. One must then leave it at room temperature for a day, by which time it should be bubbly and ready for use.
A healthy sourdough starter usually has more LAB than yeast, but may require attention to ensure the bacteria does not consume all of the available flour, leaving the yeast to die of starvation. LAB grows more quickly in wetter, warmer conditions and when whole-grain flours are used, while yeast favors white flours and drier, cooler temperatures.
Bibliography
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