Pasteurization of milk

French chemist Louis Pasteur was the founder of microbiological sciences. Born in Dole, France, Pasteur received his scientific education at the Ecole Normale Superieure in Paris. He served successively as professor of chemistry in Strasbourg and professor of chemistry and dean of the Lille Faculty of Sciences, which he organized in 1854. Three years later he returned to the Ecole Normale as director of scientific studies, a post he retained until 1867, when he became professor of chemistry at the Sorbonne.

Pasteur's studies of fermentation began in Lille when he was approached by an industrialist disturbed because undesirable products often appeared during the fermentation of sugar into alcohol by yeast. Pasteur postulated that these products came from microscopic organisms other than yeast and suggested that each particular type of fermentation was the effect of a specific microorganism, called the germ. He soon illustrated this revolutionary theory with brilliant studies on the conversion of sugar.

Pasteur claimed that types of microbes could be separated from each other by proper techniques, and could be shown to differ in nutritional requirements and in their susceptibility to antiseptics. He also suggested that just as each type of fermentation was caused by a particular type of germ, so it was with many types of diseases. Pasteur became preoccupied with the origin of microorganisms and demonstrated that each microbe is derived from a pre-existing microbe, and that spontaneous generation does not occur.