When Food Changed History: Louis Pasteur

If you've never considered the connection between beet juice and rabies prevention, read on.

This is the first installment in an occasional series about important food-related events in history. I can think of no better subject to begin with than the scientist whose discoveries led to important innovations in both food preservation and prevention of infectious disease, Louis Pasteur. And although he can't be credited with inventing the process that turns grapes into chianti and grain into amber bock, he was the first to explain the role of microorganisms in fermentation, and his work led to improvements in beer and wine making.

Pasteur was born in Dôle, France in 1822. He first gained acclaim as a young professor for his studies in how certain crystals affect light. He continued his work on crystallography at the University of Strasbourg, in the Alsace region of France, where he concluded that asymmetry was the defining characteristic of the molecules of living things, while the molecules of minerals were symmetrical—an important contribution to the scientific understanding of life. He also experimented with the effect of heat on molecular structures, and made his first foray into medical applications, developing a new and more stable isomer of quinine, which was used to treat fever.

But Pasteur's most famous discoveries were made after he became dean of the science department at the University of Lille, in a region known for its beet juice distilleries. In 1856, a local industrialist approached him about the quality problems some manufacturers of beet root alcohol were having. Pasteur set about studying yeast under a microscope.

Patrice Debré writes in his 1994 biography Pasteur, "Indeed we are indebted to fermentation for some of the most powerful symbols of our myths, at least in the Western tradition. The ancient Egyptians brewing beer, the ancient Gauls making their bread dough rise with yeast—these images evoke ancestral practices. Yet scientists, including the earliest chemists, from Paracelsus to Robert Boyle, had no convincing explanation to account for the phenomenon."

In Pasteur's time, Debré explains, yeast was thought to have only a passive role in fermentation. His experiments showed that yeast was not only the cause of fermentation, but that it was a living microorganism and that fermentation was the result of a biological rather than chemical process. His research became the basis for the new field of microbiology. It also paved the way for a number of other important advancements in science, including his debunking of the centuries-old and widely held idea of spontaneous generation—that some life forms, like rats and flies, could arise spontaneously from non-living matter under certain circumstances.

Pasteur's promotion of the germ theory—which proposed that many diseases, such as anthrax and rabies, are caused by microorganisms—led to a new understanding of how infectious disease spreads, and therefore how to prevent it. Sanitary practices in medicine followed. The capstone of his long and fruitful career, according to Debré, was his role in the development of a rabies vaccine. This led to the establishment of the Institut Pasteur, in 1887, which continues to research the prevention and treatment of infectious disease.

Of course, the achievement most obviously associated with Pasteur, and most relevant to this blog, is the process of pasteurization. In 1863 Pasteur received a letter from one of Napoleon III's aides, commissioning him to study the spoilage of wine—a matter of great urgency in France, where wine was vital to the nation's cultural life and economic prosperity. The aide wrote, "The Emperor is firmly convinced that it would be of the highest importance that you turn your attention in this direction at the time of the grape harvest." Drawing on his earlier research, Pasteur developed a method of heating wine to slow microbial growth and prevent spoilage, without destroying the beverage in the process. Pasteurization, as it came to be known, is still used to treat wine, milk and other perishable liquids.

So next time you enjoy a pinot noir, or chocolate milk, raise your glass to Louis Pasteur.

Lisa Bramen | | READ MORE

Lisa Bramen was a frequent contributor to Smithsonian.com's Food and Think blog. She is based in northern New York and is also an associate editor at Adirondack Life magazine.