What contribution did Louis Pasteur make to the understanding of the process of fermentation?

Pasteur became a professor of chemistry at the University of Lille in 1854, and soon began studying fermentation in wine and beer. He became convinced "the germs of microscopic organisms abound in the surface of all objects, in the air and in water." He determined that such micro-organisms could be killed by heating liquid to 55 degrees Celsius (about 130 degrees Fahrenheit) or higher for short periods of time. This simple process became known as pasteurization, a process used today in milk and many other beverages.

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