All bread is made with four simple ingredients: flour, water, salt, and yeast. Yeast is a microscopic organism that plays a part in making many of the world’s favorite foods from wine to beer and kimchi through the process of fermentation. What makes a bread a sourdough bread is that the yeast used in the fermentation of the dough is wild yeast rather than commercially available yeast known as “baker’s yeast.”
There’s nothing inherently better or worse about using wild yeast or commercial yeast—some of the best breads in the world use a mixture of both! But natural, wild yeast brings an exciting range of flavor, experimentation, and health benefits that are typically not found in breads made with only commercial yeast.
The fascinating transformation the dough goes through under the influence of wild yeast gives the bread better keeping qualities due to the unique environment wild yeast creates, and the diversity of healthy bacteria present in the fermentation makes the bread much easier to digest than other breads and contributes to healthy digestion overall.
Diverse, wild yeast also provides a huge range of flavor possibilities not present in commercial yeast fermentation. A common misconception is that sourdough must taste sour! Sourdough often tastes sour, but it doesn’t have to—it can taste anywhere on a range from sweet, floral, and creamy, to bright, sharp, and sour. The skill of the sourdough baker is in managing the fermentation to balance these flavors to get exactly the flavor profile and texture desired.