Pasteur

Louis Pasteur was a chemist, not a physician. In the early 1860s, the French wine industry had a problem: barrels of wine were spoiling unpredictably, turning to vinegar or developing off-flavors. Emperor Napoleon III personally asked Pasteur to investigate. Pasteur discovered that microorganisms in the wine were causing the spoilage, and that heating the wine briefly to 50-60 degrees Celsius killed them without destroying the flavor.

He patented the process on April 11, 1865. The French called it pasteurisation. Wine producers adopted it immediately. Beer brewers followed. The original targets were alcoholic beverages, and for twenty years that is all the process was used for. Milk was not part of the conversation — most Europeans drank milk fresh or not at all, and the idea of heating it would have seemed bizarre.

It was Franz von Soxhlet, a German chemist, who in 1886 proposed applying Pasteur's technique to milk to reduce infant mortality. The suggestion was controversial. Dairy farmers resisted. Consumers worried that heated milk was less nutritious. New York City did not require milk pasteurization until 1914, and some states held out until the 1940s. The process that saved wine had to fight for fifty years to be allowed near milk.

Pasteur died in 1895, aware that his name had become a verb but probably not foreseeing that pasteurize would become almost exclusively associated with dairy. He spent his career on fermentation, silkworm disease, and eventually rabies. The milk connection came after him. His name on every carton in every refrigerator is a posthumous honor he did not plan for.