386 MICROBIOLOGY OF SPECIAL INDUSTRIES. 



drinks by destroying all life present, but rather to accomplish the specific 

 purpose of destroying certain species of organisms in the material to be 

 pasteurized, thus effecting a partial arrest of the natural fermentation 

 along certain chosen lines by removing from the field of activity those 

 organisms whose presence serves to inhibit or pervert the desired fer- 

 mentative result. 



The principle of pasteurization may be said to have originated in the 

 early work of Spallanzani and Scheele, already mentioned, and was 

 employed by Appert in his later investigations. The operation as employed 

 by Appert does not, however, appear to have found general application 

 until Pasteur revived the method, and as a result of his activities in attempt- 

 ing to secure a general adoption of the practice to prevent the spoiling of 

 wine, the process was named from him. 



SPECIFIC APPLICATION. Beer. Pasteurization is of economic im- 

 portance particularly in. the dairy and the fermentation industries. In 

 brewing, "the process of pasteurization is in use with even the smallest 

 brewers in the United States, beer being pasteurized even for local con- 

 sumption." The beer is pasteurized in bottles by being submerged 

 for one half -hour in water heated up to 60 to 65. In European countries 

 pasteurization of beer in jugs, as well as in bottles, is practised. Experi- 

 ments have been made in pasteurizing beer in large metal containers, 

 steel, copper, aluminum and tin having been tried, but without complete 

 success as yet. The process destroys the flavor. 



Fruit Juices. The essentials in the pasteurization of wine and fruit 

 juices are similar to those for beer. There is, however, no universal 

 rule of application. Details of the process must be arranged to suit the 

 character of the different liquids under treatment. 



Cream and Milk. Pasteurization as employed in the dairy industry va- 

 ries in its method of application according to the purpose for which it is 

 used. In factory butter-making, it must be employed to secure the best 

 results. Milk as ordinarily received at creameries contains a widely vari- 

 ant microbial flora, many of the species exerting a greater or less influ- 

 ence in determining the flavor of the finished product. By pasteurization 

 of the cream, the butter-maker destroys most of the organisms present, 

 and by the use of a culture starter of lactic bacteria, a necessary conco- 

 mitant of pasteurization, he is able to control definitely the fermentation 

 and is assured of a uniform quality of product from day to day throughout 

 a season. An added value of pasteurization is that thereby all pathogenic 



