🍷 Louis Pasteur

Louis Pasteur (1822–1895) was a French scientist whose work changed both winemaking and medicine. He was born in the French town of Dole in the Jura region, known for its wines. Near his home region he began to study why wine turns out good or spoils.

In the 1860s Pasteur showed that fermentation is caused by living organisms, yeasts, while spoilage of wine is caused by other microbes, for example bacteria that turn wine into vinegar. Before that the causes of spoilage were unknown. In 1866 he published the book "Studies on Wine".

Pasteur suggested heating wine to kill harmful microbes without destroying the taste. This method is called pasteurisation. For wine it was used less often, because heating can change the taste. Later heating was applied to milk: pasteurised milk is made on the same principle.

Pasteur's work explains why wine ferments, why it spoils and how to avoid it. It lies at the base of modern oenology, the science of wine.

Pasteur did not invent heating wine in sealed vessels, and he admitted as much: Nicolas Appert had proposed it earlier, though Pasteur argued that he put the method on a scientific footing. He first tried 60–100 °C, then settled on 50–60 °C in closed vessels for an hour or two, and announced it to the Academy of Sciences on 1 May 1865. At the 1867 Exposition Universelle the wine-heating method won a grand prize.