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Louis Pasteur and Alcoholic Fermentation
Louis Pasteur, Wine Disease and Napoleon
Written by Brendon Barnett   

Louis Pasteur and Napoleon IIIFor some time during the 19th century, the French wine industry was burdened by different diseases that caused wine to become sour, bitter or flavorless. Knowledge of French wine diseases spread throughout Europe, greatly damaging the wine export sector in France. An English merchant said this just after the treaty agreement between France and Great Britain in 1863:

In the beginning we eagerly greeted the arrival of these wines, but we soon made the sad experience that this trade caused great losses and endless troubles because of the disease to which they are subject.*

Written by Brendon Barnett   
Thursday, 29 December 2011 09:37

Louis PasteurLouis Pasteur first devoted himself to the study of fermentation in 1856, when he is approached by M. Bigo, a local industrialist in Lille, and asked for advice concerning the production of alcohol in beet juice. Apparently Bigo was experiencing large vats of beet juice turning sour instead of alcoholic as expected. Pasteur agreed to help with the problem and this began his first experiment in the area of fermentation.

Pasteur visited the factory where the beet juice was being produced and observed the differences in some of the vats. He smelled the fermentation process in the first batch. In that specific vat, the juice smelled fine and the juice was clearly fermenting into alcohol. But in other vats the odor was sour and in some cases putrid. A thin layer of grime covered the top of the juice in these vats. This both puzzled and interested Pasteur and motivated him into looking at exactly what was going on during the fermentation process. Not only was this scientifically interesting, but solving this problem would save Bigo great deals of money from spoiled beet juice and would also do the local community a service.

Louis Pasteur and His Patented Beer Making Equipment
Written by Brendon Barnett   
Tuesday, 24 November 2009 11:07

Pasteur Brewing Tanks
Brewing tanks patented by Louis Pasteur on
January 28, 1873

Germ Theory

In a simple experiment of drawing through an aspirator a current of outside air through a tube containing a little plug of cotton wool, Pasteur demonstrated that, as the current passed it deposited on this sort of filter some of the solid corpuscles contained in the air. After a year's study, Pasteur reached this conclusion : "Gases, fluids, electricity, magnetism, ozone, things known or things occult, there is nothing in the air that is conditional to life, except the germs that it carries." Pasteur was convinced that the atmosphere itself contained nothing which could produce life, but in fact life did exist within it.

Germ Theory and Beer

With a simple, yet insightful application of this discovery and the ground breaking science in Germ Theory of Disease and his Studies on Fermentation, Louis Pasteur revolutionized beer and wine making processes. He posited that the exposure of beer and wine to the open atmosphere would contaminate the substance, due to the living organisms in the air, responsible for the processes of fermentation. Therefore, in order to effectively protect a substance from infection, not only must it be properly heated to eliminate or "pasteurize" any living organisms already within the substance, but during and after the heating takes place, the substance must remain closed off from any atmospheric influences.

Previously, the wort was boiled and then exposed to the air for cooling, before the yeast was introduced to catalyze fermentation. Pasteur later developed and patented a device that would allow for the proper brewing of beer, always ensuring the wort stayed protected from outside influences, right up to the point of distribution. In Pasteur's process, the wort is kept in closed vessels and cooled by spraying the outside of the vessel with water. A special yeast was introduced into the mash after it cooled, thus preventing contamination of the wort with stray wild yeasts floating through the air.

The Pasteurization of Beer
Written by NY Times   

During the terrible days of the supremacy of the Commune in Paris, at the end of the Franco-German war, Pasteur was occupied in the laboratory of M. Duclaux, at Clermont-Ferrand, in studying the diseases of beer, with a view to attempt to raise French beer to the higher standard of the German brewers. Beer is naturally more prone to disease than wine, on account of the comparatively large quantity of gummy and sacchari9ne matters which it contains in a state favorable to rapid decay. When the fermentation of the wort of beer sets in at the high temperature to which it is raised in mashing the liquid requires to be rapidly cooled. So long as it remains between the temperatures of 77˚ and 95˚ of Fahrenheit’s scale it is peculiarly liable to be attacked by the injurious ferments proper to acetic, lactic, and butyric acids. If the must of beer were spontaneously fermented, like the must of grape juice, an acid of putrid liquid would invariably be produced in the place of beer. In the old process of what was technically known as high fermentation, which is also the one that is still employed with the bitter beers and pale ales of England, the fermenting liquid was kept in barrels, at a temperature ranging from 64˚ to 68˚ Fahrenheit. In the process of “low fermentation” which is more generally employed by the brewers of Germany and France, a slow fermentation is established at a lower temperature, during which the yeast settles down to the bottom of the tubs and casks.



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louis_pasteur_delivering_first_rabies_inoculation_on_joseph_meister_20090420_1148554081Louis Pasteur was a microbiologist and chemist from Dole, France. Learn more about his childhood, history at the university and his ground-breaking work that led to the development of modern medicine. We owe the creation of vaccinations, pasteurization and many more applications of science to Louis Pasteur.

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