THE MILK CONTRACTOR 265 



butter and for city milk. The attempt has been made to utilize it in 

 cheese making but so far with only limited success. 



The Danes were the first to apply pasteurization in butter making. 

 Acting on Storch's discovery in 1890, that the flavor of butter could be 

 changed and consequently controlled by the addition of different kinds 

 of bacteria to ripening cream, they adopted the use of starters in butter 

 making. The starter is prepared with certain precautions by growing 

 a known mixture of bacteria in milk that has been heated nearly to boiling 

 and when ready is used to inoculate the cream which is either obtained from 

 pasteurized milk or is itself pasteurized. The Danes used the flash proc- 

 ess of pasteurization and adopted 185F. as the legal minimum because 

 the studies of Bang in 1894 showed that the B. tuberculosis is killed at 

 that temperature and because he persuaded them to protect their young 

 stock from this and other diseases by enacting a law in 1898, requiring 

 that all skim-milk should be pasteurized before being returned to the 

 farm. The Danes were so very successful in the London and other 

 markets, with their butter made from pasteurized cream that the process 

 of manfacture was gradually adopted by others and now in the United 

 States and elsewhere many buttermakers are using it. 



Various difficulties that arise in the manufacture of cheese are of 

 bacterial origin so that it would seem that the pasteurization of the milk 

 which is used might be helpful but it has not proved so because of two 

 difficulties that are encountered, to wit: that heated milk coagulates 

 slowly with rennet, giving a loose spongy curd that is too fragile to be han- 

 dled successfully; and second, it produces a curd that expels whey slowly. 

 As the result of experiments conducted from 1905 to 1911, Sammis and 

 Bruhn have brought out a process of cheese manufacture wherein the 

 milk is pasteurized by the flash process at 160 to 165F., and is afterward 

 acidified with hydrochloric acid which restores its coagulability with 

 rennet and brings the acidity to a point where the whey is rapidly expelled 

 by the curd. Several factories have adopted the process; the Bowman 

 Dairy Co. of Chicago has equipped two of its milk stations with outfits 

 to utilize the process, and during the flush run of milk in the summer of 

 1914, used it in making 335,000 Ib. of cheese. Sammis has also devised 

 two methods of making cheese from the buttermilk of pasteurized cream. 



The Work of Koplik. In this country, the introduction of pasteuriza- 

 tion to the city milk business was gradual. Heated milk was first used 

 by a few pediatricians. Then, in 1889 the first milk depot was opened in 

 New York City under the direction of Dr. Henry Koplik. This insti- 

 tution distributed pasteurized milk and through its operations the public 

 began to understand what pasteurized milk was, and to use it. The 

 physicians of that day used rather higher temperatures in pasteurizing 

 than are recommended now. Dr. Koplik pasteurized the milk he dis- 

 tributed at 185 to 195F. because he found that milk so heated kept 



