Surdegsbröd

Sourdough or sourdough bread is a bread made by allowing the dough to ferment using naturally occurring lactobacillaceae and yeast before baking. The fermentation process produces lactic acid, which gives the bread a sour taste and improves its keeping-qualities. Sourdough is one of the most ancient forms of bread, and it was the standard method of breadmaking for most of human history. It was replaced by barm during the Middle Ages, which was then replaced by industrially produced baker's yeast in the late 19th and early 20th centuries. In the Encyclopedia of Food Microbiology, Michael Gaenzle writes: "One of the oldest sourdough breads dates from 3700 BCE and was excavated in Switzerland, but the origin of sourdough fermentation likely relates to the origin of agriculture in the Fertile Crescent and Egypt several thousand years earlier", and "Bread production relied on the use of sourdough as a leavening agent for most of human history; the use of baker's yeast as a leavening agent dates back less than 150 years". Sourdough remained the usual form of leavening down into the European Middle Ages until being replaced by barm from the beer brewing process, and after 1871 by purpose-cultured yeast.

Source: Wikipedia