When you hear Louis Pasteur, will surely be recognized as a great scientist and biologist. His discoveries are important and implemented to this day helping humankind stay safe and improving our general health. But have you ever heard of his revenge? And how a scientist and an intelligent mind of his caliber would actually achieve it?

When the French Academy of Sciences put a 2,500 francs prize for whoever could solve a question of beer in the 1800s French scientists were excited to bring beer into their labs. But the great Louis Pasteur decided to tackle this problem not for the money but for revenge. And by 1870 Louis Pasteur had already revolutionized several industries thanks to his scientific breakthroughs. Advancing germ theory, milk production, vaccinations for several diseases, and strangely enough doing work with silkworms that allowed for faster silk production. Louis Pasteur certainly didn’t need any more money or accolades by studying beer. But world events would set the greatest mind in biology at the time on a path of research and revenge.

It all started with a war

In 1870 beer was probably one of the last things on the mind of Louis Pasteur. In July France declared war on the Northern German Federation. After years of provocation and some incendiary telegrams. While the French did manage to score a couple of early victories it quickly became clear that the great French military minds of two generations prior were long gone. And by September the Germans were approaching Paris.

After besieging the city for four months the French were finally forced to surrender in January 1871 handing the French a humiliating defeat and setting up a rivalry that would last through the end of World War II. The Franco-Prussian war had a big effect on many French and German citizens.

Louis Pasteur was angered and saddened by the events. First, his son enlisted to fight in the war. And although he wasn’t a casualty there’s no doubt that parental concern weighed heavily on Pasteur. Second, Pasteur’s work brought a lot of prestige to France. Making them the envy of the world’s scientific community, especially in biology. But all this national pride was quickly erased by the French defeat. And while it certainly didn’t undo Pasteur’s work the loss of pride was something that Pasteur himself didn’t forget. Perhaps most important was that Louis Pasteur was in negotiations with the French government to construct a new lab when the war broke out. Obviously, events delayed the project for years and the potential for even more scientific breakthroughs was lost with it. So with his national pride hurt, a new lab delayed its natural that Louis Pasteur felt resentful of the German state in the years following the war.

French Academy of Sciences

Louis Pasteur was not a fighter or a politician. So he elected to take out his frustration in the best way he knew how, with science. Nearly a century before French chemist Antoine Lavoisier proved that fermentation caused sugar to convert to CO2 and alcohol in beer and wine. But with this step forward in brewing science, a great debate was ignited. In one camp were those scientists who believed that fermentation was nothing more but a slow chemical reaction that happened in the casks of wine and ale.

In the other camp were those who thought it was some sort of biological process but they didn’t know exactly what caused it. It could have been any number of germs, bacteria, or other theorized microorganisms. The debate became so intense that the French Academy of Sciences put a bounty proving what caused fermentation to 2,500 francs or about $ 50,000. This question went unsolved for 80-something years and while the cash prize was encouraging beating the Germans at beer science certainly sounded like a sweet form of national revenge.

Genius at work

Pasteur immediately got to work on a series of experiments using filtered grape juice. First, he set aside 10 bottles of grape juice as a control. In the second group, he had 10 bottles to which he added a little bit of water he used to wash the skin of the grapes. In the third group, he added the same grape skin water but boiled it first. And in his final group, he added the extra sweet juice drawn from the center of the grape.

Naturally, only the second group of bottles fermented. And when he examined the samples from each group under a microscope, he clearly saw that yeast cells were present in the second group, proving once and for all that yeast was the agent responsible for turning grapes into wine or barley into beer. But he didn’t stop there. Now that he knew yeast was the microorganism responsible for fermentation, he wanted to know what other microorganisms did to a batch of good beer.

In 1876 he published a book Studies in beer which outlined his findings. Bacteria like Lactobacillus could turn a beer sour, and some microorganisms could kill the yeast leading to an under-fermented batch. Perhaps the most important thing in the book was the technique he laid out that allowed brewers to understand how to experiment and determine what was happening in their beers and why one batch was good and another one would spoil. To leave no doubt about his motivations for studying beer Pasteur wrote the following first paragraph of Studies in beer.

Our misfortunes inspired me with the idea of these researches. I undertook them immediately after the war of 1870 and have since continued them without interruption with the determination of perfecting them and thereby benefiting a branch of industry wherein we are undoubtedly surpassed by Germany.