About Sourdough bread
Wikipedia Article About Sourdough bread on Wikipedia
Rather than leavened with active dry yeast, is made from a starter of fermented flour, sugar, and water, which supports a culture of natural yeast. Sourdough breads have a distinctive sour or tangy taste.
A bread with a slightly sour, tangy flavor created by using a special Yeast Starter as the Leavener. San Francisco is known for its superior sourdough bread and many food stores in the area sell packages of dry sourdough starter for home bread bakers. Though most sourdoughs are made from all purpose flour, there are many delicious variations including those made from whole-wheat or rye flour.