Dear wine lovers,
We continue with "stories about wine", and this time we are talking about Louis Pasteur (Louis Pasteur, 1822-1895). Pasteur, a chemist by training, is associated with microbiology, but little is known that his first works were in the field of wine production in France. Namely, he gained initial fame working for winemakers, the beer and vinegar industry, examining problems in the production of wine and beer and what would be the methods to prevent their deterioration. The "pasteurization" method, which he applied to control wine spoilage, is well known. Initially, the liquid (wine) was heated to a temperature of 63 to 66 °C for 30 minutes. Today, the method that involves short-term (15 seconds) heating to 71.6 °C is more often used. As far as alcoholic beverages are concerned, today this method is used primarily in the beer industry.
Through his experiments, Pasteur significantly improved the knowledge of microbiology, especially bacteriology and the science of vaccines. However, we should mention his early works related to the production of (wine) vinegar. Later, Pasteur proved that fermentation is due to the presence of living organisms (yeasts) and that different types of fermentation are due to differences in microorganisms. He established that there are different types of yeasts that can significantly affect the gustatory properties of wine. In addition to alcohol and CO2,2during fermentation under the influence of yeasts, glycerol is also synthesized. Pasteur described the deterioration ("tourne") of wine under the action of bacteria, when the acidity of the wine decreases as a result of the addition of tartaric acid, and the concentration of undesirable volatile acids increases. He is also credited with the first knowledge of the so-called carbonic maceration, i.e. fermentation of whole grape berry in the absence of oxygen and in a carbon dioxide (CO2) atmosphere.2However, this great scientist also had misconceptions, such as his sentence: "yeasts make wine, and bacteria spoil it." Namely, he did not accept that there are also desirable bacteria, such as those that cause malo-lactic fermentation.
It can be said that oenology has made enormous progress thanks to the work of Pasteur, who observed and explained at that time a magical phenomenon: the transformation of grapes into wine. He showed that fermentation is the result of the action of living organisms. Ultimately, he was the first to use the term"fermentation"for any process and activity of microorganisms under anaerobic (without oxygen) conditions.