264 MODERN DAIRY PRACTICE. 



shall see directly, however, that they soon make their pres- 

 ence felt. In some kinds of cheese it is considered im- 

 portant that the coagulation takes place rather slowly, in 

 40 to 50 minutes, and the temperature during the same is 

 increased from about 86 to 104-131 F., a temperature 

 especially favorable to certain forms of bacteria. It is 

 then cut and run through a curd- mill, and the whey is re- 

 moved. 



Some kinds of cheese require that the curd be kept 

 warm continually, so that it will rapidly turn acid, by 

 which means it assumes a distinct sour taste and flavor; it 

 is often also considered advantageous to continue the 

 heating even in the press. In this way highly-favorable 

 conditions of temperature are for several hours offered the 

 bacteria in the curd. There is plenty of moisture, and the 

 casein as well as the milk-sugar are excellent nutritive sub- 

 stances for bacteria; these therefore multiply rapidly in the 

 curd. The action of the bacteria is shown from the fact 

 that in nearly all kinds of cheese we observe during the 

 first twenty-four hours small holes throughout its mass. 

 In some kinds the holes soon disappear; in others they 

 remain and sometimes even grow larger. They arise on 

 account of a gas generation (especially carbonic-acid gas*) 

 caused by certain bacteria, butyric- and lactic-acid bac- 

 teria being the main ones. This fermentation generally 

 belongs to the normal changes in the cheese. If the de- 

 sirable forms of bacteria are not present, or are present in 



* According to Baumann the gases causing holes in cheese con- 

 sist mainly of carbonic acid (63 per cent) and hydrogen, and also 

 small quantities of other gases, but no hydrocarbons. (Landw. 

 Vers. Stat., 42, p. 214). See also Adametz, MUch-Zeitung, 1893, 

 p. 220. W. 



