Image Number K7250-35
Bakers in the Bay Area insisted their sourdough bread couldn't be duplicated
farther than 50 miles from the center of San Francisco. Didn't know why, either.
It just couldn't.
Enter ARS researchers, who knew there was a scientific answer to the mystery
of sourdough bread. They started looking for clues.
One puzzling thing about the brad was its high acetic acid content, which
contributed to its tangy taste. Yeasts generally can't tolerate acetic acid.
Obtaining samples of starter doughs from five local bakeries, a scientist
found in all five a bacterium never before discovered. Naming it Lactobacillus
sanfrancisco, he spent several months and tried 30 different substances
before finding a medium in which it would grow.
The other thing he found was an unusually acid-tolerant yeast, Saccharomyces
exiquus. It worked with the bacterium in a symbiotic relationship to produce
the bread's unusual flavor, crust, and texture. Comments the scientist: "It
was a happy marriage between two noncompetitive bugs."
So now San Francisco-style sourdough bread can be baked anywhere in the
world. Which turned out not to be bad news for the City by the Bay. Pure
cultures of L. sanfranciscoare now grown commercially and are commonly
used by San Francisco bakers to control the quality of their product.
Photo by Scott Bauer.
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