The man who made better beer and vaccines

Louis Pasteur’s acclaim is such that he’s become a household name: in the 1860s he demonstrated that undesirable fermentation of wine and beer could be prevented by heating the beverages. The technique became generically known as pasteurisation.  

Although his original goal was to find a way of preserving the integrity of beer, it is with milk that we most commonly associate the process.

Pasteur, who died on September 28, 1895, was born in Dole, in eastern France, on December 27, 1822. By all accounts he was a middling student as a young man, more interested in art than science, but he persevered and eventually earned a master’s degree and doctorate from the renowned École Normale Supérieure school in Paris.

Having aided the French liquor trade, he was next tasked with solving a blight in the country’s silk industry. Studying silkworms bred by his wife, Marie, he found the cause of a devastating infection was a pair of parasites, and showed how infected worms should be isolated and destroyed.

Pasteur was among a minority of scientists of his time who subscribed to the relatively new “germ theory”, the idea that many diseases are caused by the presence and actions of specific microorganisms in the body. 

In his studies, he began researching anthrax, a disease principally affecting sheep and cattle, but which can also be transmitted to humans. But his attention was soon drawn to fowl cholera, and it was here that he made his breakthrough discoveries concerning vaccines.

Influenced by Edward Jenner, whose work is widely regarded as the foundation of immunology, Pasteur reasoned that if a vaccine could be found for smallpox, vaccines could be found for all diseases.

The basis of many of Pasteur’s discoveries was established early in his career, when he was just 26 years old and working in the new field of crystallography. 

Working with a compound called tartaric acid, and another, named paratartaric acid, chemicals found in the sediments of fermenting wine, Pasteur deduced that even though the two compounds had the same chemical composition, they must somehow have different structures, and he set out to find evidence to prove his hypothesis.

Through “incredibly meticulous” experimentation, writes chemistry historian Thomas Holmes, Pasteur “established that composition alone does not provide all the information needed to understand how a chemical behaves. His work allowed chemists to start thinking about the structure of molecules in terms of their stereochemistry, a field that remains important in chemistry research.”

Pasteur suffered a stroke in 1894, from which he never fully recovered. He died the following year and was given a state funeral.