In September 1854, Mr.Pasteur became interest in the alcohol industry, and one of the most important processes in making alcohol was fermentation. At that time, an alcohol-making plant in Lille encountered technical problems, and asked Pasteur to help study the fermentation process. Pasteur visited the plant to investigate, and brought various beetroot juice and fermented liquid back to the laboratory for observation. After many experiments, he found that there is a kind of globular body much smaller than yeast in the fermentation liquid, which is yeast when it grows up.
Soon, the buds grow on the fungus, fall off after growing up, and become new globules, in the process of continuous circulation, beetroot juice “ferments”. Pasteur went on to find out that the alcohol and carbon dioxide gas produced during fermentation were produced by yeast to decompose sugar. This process can occur even without oxygen, he believes that fermentation is the anaerobic respiration of yeast and the control of their living conditions, which is the key to wine brewing.
At that time, the French wine industry faced a headache, that is, the wine will become sour after brewing and can not be drunk at all. And this kind of acid change often occurs. Mr.Pasteur was invited to study the problem. After a long period of observation, he found that in the process of wine deterioration, there was a biochemical process that played a key role – fermentation phenomenon. He observed under a microscope that there was a round yeast cell in the wine without deterioration,while a long strip of lactobacillus in the acid liquor. Yeast can convert sugar in beet juice into alcohol, but if lactobacillus mass reproduction in wine liquid, it will make wine sour.
After figuring out why the wine turned sour, Pasteur began to solve the problem. Since wine souring is caused by lactobacillus, as long as killing lactobacillus, can guarantee the flavor of wine? The easiest way to sterilize is to boil, it’s a food processing method with a long history, but if you boil the wine, the alcohol will volatilize clean, if the wine doesn’t exist, what’s the flavor?
But Pasteur didn’t give up. He carried out a series of tests, used various methods to heat the liquor, and came up with many ways to cool the wine liquid. In 1862, he successfully killed lactobacillus by heating and cooling for the first time, and his experiment ushered in significant progress! Later, in repeated experiments, Pasteur finally found the way to kill lactobacillus. In fact, wine doesn’t need to be boiled, just heated to 50 ℃ ~ 60 ℃,At this time, the wine will not evaporate, the acidity will disappear, and even the taste will become softer. This method saved the French wine brewing industry.