Featured Biography: Louis Pasteur: the father of pasteurization made brewing fast and easy


Kirsteen Wolf

The Broadside

Beer drinkers owe a lot to Louis Pasteur and the famous scientist might have raised a glass to the brew himself. In studying the effects yeast and microbes on the beer making process, Pasteur discovered pasteurization, taking the guesswork out of beer making success and allowing larger quantities to be brewed with predictable results.


Louis Pasteur (1822-1895) was born in Dole ,France and grew up in the nearby town of Arbois to a family of tanners. It is said that Pasteur inherited his work ethic from his parents who were tireless in their support of their children. While Pasteur was very talented as an artist—rendering detailed portraits of his parents and friends in his college years—his father wanted him to become a professor of the local college and Pasteur himself had scientific leanings. A head master directed him to a prestigious school where he began his scientific education and eventually came to teach in Strasbourg. Through his teaching career, he was known for his discipline and his inclination to teach through experimentation, often preferring to conduct class outdoors instead of in a lecture hall.

Pasteur was working as the dean of science faculty at the University of Lille when he was approached by a manufacturer of alcohol who needed his help to solve a mystery. During the 19 century, beer and wine would go sour for no apparent reason. When industrial batches of beer and wine went bad, the economic consequences were significant.

Pasteur studied the ingredients that were present in the successful batches of beer, and compared it to all the batches that went sour . While the yeast was rounded and easily identifiable, all the soured batches contained a rod-shaped microbe. Pasteur discovered that there were microorganisms that caused things to spoil. Pasteur had to prove that microbes hitched a ride on dust that entered batches of beer (or other beverages) and caused it to turn into lactic acid.

One proof came in the form of the famous swan neck flask. Pasteur filled the container with juice, sterilized it and then elongated the flask’s neck to slope downward and then slightly up. The contents of the flask remained sterile  when the flask was sealed and remained sterile after the necked was snipped open but spoiled immediately when the contents were tipped into the neck of the flask, coming in contact with the dust that was trapped after air was introduced. Some of his flasks are at the Pasteur institute where they are still sterile after 100 years.

According to David V. Cohen of Harvard University, Pasteur discovered that “if pure cultures of microbes and yeasts were added to sterile mashes, uniform, predictable fermentations would follow.” So it was the yeast that was turning sugar into alcohol and it was the microbes that had to be dealt with in order to prevent spoilage.

And here’s something you can really drink to. Pasteur used his discoveries from the beer and wine mystery to consider the possibility that microbes were causing disease. It was these theories that caused surgeons to sterilize their instruments , leading to a phenomenal drop in the infection rate. Pasteur then went on to study and treat anthrax and rabies by isolating the microorganism that caused these diseases.

So when your bartender washes his hands after leaving the bathroom, raise your glass of perfectly brewed beer to Louis Pasteur.

You may contact Kirsteen Wolf at kwolf@cocc.edu


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