His original inquiry into fermentation, published in 1857, came at the request of a distillery in Lille, a city in northern France. Pasteur was a professor of chemistry at a nearby university when the distraught father of one of his students approached him. His distillery business, the man confessed, was failing for some mysterious reason. Rather than getting alcohol from his beet juice, the man told Pasteur, he was getting something like sour milk. Pasteur began an investigation and discovered that the juice was fermenting into lactic acid rather than alcohol. The cause, he discerned, was a
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