Sourdough bread is called “sourdough” because it is made using a naturally occurring yeast and bacteria culture known as a sourdough starter. The starter is a mixture of flour and water that is left to ferment over time, which allows wild yeast and bacteria to colonize it. This fermentation process produces lactic acid and acetic acid, which give the bread its characteristic tangy, slightly sour flavor.
The use of sourdough starters in bread-making dates back thousands of years, and has been used by cultures around the world. Sourdough bread was a staple food for many people throughout history because it was easy to make using simple ingredients, and the fermentation process helped to preserve the bread and extend its shelf life.
Today, sourdough bread is still popular for its unique flavor and texture, and is often prized for its nutritional benefits and potential health benefits.