Background on Sourdough

Sourdough bread is probably the most ancient of leavened breads. Early wheat sources had thick hulls that required boiling to remove thereby denaturing the gluten forming proteins. You get a nice gruel, though. The first fermentation of raw wheat was likely accidental contamination by airborne yeasts. Once harnessed it was passed down from batch to batch by the saving back of a small supply of dough for the next generation of bread.

The earliest of breads was a sourdough and its lineage can be traced to current day. Hull agriculture changed from hard husk to softer husk and with the advent of grinding equipment harnessed to animal, water & wind power yeast technology was cutting edge. Mother doughs can be decades upon decades old and are carefully guarded trade goods. Some San Francisco mother doughs are reputed to be more than 150 years old. Old mother doughs are inherently resistant to contamination through some sort of antibiotic action much like the beneficial molds in cheese.

"San Francisco style" sour dough is nothing but a local sour dough unless it was imported just yesterday from the city. A mother dough transported from San Francisco will quickly mutate from exposure to local airborne yeasts into a local microbial content variety. With proper care and feeding a local variety of mother dough should last, at a minimum, several years.

Beer sediment began the age of rapid rise yeasts and cut a culinary crossroads from sourdough. Sour bread from a beer sediment yeast, your traditional white and wheat breads, is considered a defect from letting the yeast fermentation process go on too long. If the bacteria creates too much acid with this type of yeast it will die giving the bread an ammonia like aftertaste that is nothing like the complex sour flavors of wild yeast breads.

What separates the two microflora these days is a mere Saccharomyces cerevisiae vs. a Saccharamyces exiguus. Cerevisiae meaning beer and exiguus meaning scant or small. Sour doughs are acidic with a pH between 3.8 and 4.5.

The sourness of sourdough doesn't come from the wild yeast but rather from the acids that are produced by the various bacteria that thrive in the lower pH values. The distinctive sour taste has a wide variety of flavors based on the interactions with the natural bacteria (lactobacillus and acetobacillus being the main two) have with your local yeast. The bacteria feeds off the enzyme released sugars within the dough.

There are many systems for building and layering up to a barm, a starter dough for sourdough. The mother dough you start out with may change over time as your usages change: percentage of starter to use, method of starter, fermentation times and temperature, additional ingredients and blends of flavors.

Wild yeast doesn't have to be caught. It's everywhere around us. It is the white powdery substance you sometimes see on skins of plums and grapes. "Capturing" the wild yeast in a starter dough isn't a trick but a careful cultivating of nutrients and sugars to keep it alive.