THE PASTEURIZATION OF MILK 



cay has probably been practised since the discov- 

 ery of fire. The earliest record of the application 

 of heat to food in a scientific way was in 1872, 

 when Sheele, the well-known Swedish chemist, 

 discovered that vinegar could be preserved against 

 spoiling by heating it. Soon after this other peo- 

 ple began to preserve fruits, vegetables, milk, etc., 

 v/ by heating them in closed vessels. No scientific ex- 

 planation, however, of the reason why the heating 

 process preserves these foods appeared until I860 

 to 1870, when Pasteur, in his studies as to the 

 causes for the deterioration which took place in 

 wines and beers, discovered that there was certain 

 forms of life previously unknown whose unchecked 

 growth gave to liquor its bad flavors, etc. These 

 were termed by Pasteur "diseases." He discovered 

 that by heating beer and wine to a temperature of 

 158 to 176 F., and holding the fluids at these 

 temperatures for a period of time, the "disease 

 germs," as he called them, were destroyed and the 

 flavor of the liquor was improved, the loss by 

 spoiling being at the same time prevented. 



This discovery was of immense financial benefit 

 to Europe, and in consequence the heating of wines 

 and beers became very generally practised, the 

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