CHEESE 



621 



Cheese with which they worked. In regard to the bacterial flora 

 Jin Emmenthaler cheese the authors stated that the cultures iso- 

 lated could not be grouped by fermentation tests, but were sharply 

 differentiated by morphologic characters into cocci, long rods, 

 and short rods. The rods included typical cultures of Bacillus 

 bulgaricus and also all gradations between typical cultures and 

 | those producing no acid in milk. In young cheese short rods 

 [were present almost exclusively. They decreased slowly in num- 

 jber as ripening progressed, while the long rods increased. After 

 six to eight weeks both groups were present in about equal numbers. 

 At the end of the ripening period the long rods were predominant. 

 These long rods produce a small amount of proteolysis. 



Extensive studies of American Cheddar cheese were made 

 by Evans, Hastings, and Hart. The authors believe that the 

 factors involved in ripening of Cheddar cheese are: 1, pepsin con- 

 tained in the rennet; 2, lactic acid formed by lactic acid bacteria 

 from milk-sugar, the acid activating the pepsin; 3, the enzym 

 galactase, and 4, certain biologic agents other than those simply 

 concerned in the first lactic acid fermentation. In Cheddar cheese, 

 as in Emmenthaler, three groups of organisms are active, namely : 



1, lactic acid bacteria of the streptococcus group; 2, lactobacilli, 

 and 3, micrococci. By studying different groups' after inocula- 

 tion into 300 c.c. of sterile milk and after incubation for four 

 months the authors found the following substances:, formic, 

 acetic, caproic, propionic, butyric, citric, and lactic acids. The 

 lactobacilli produced large quantities of lactic acid, both active 

 and racemic. This group is also held responsible for the pungent 

 taste which develops during the later ripening period of Cheddar 

 cheese. 



Among the soft cheeses, Camembert has received the greatest 

 amount of attention. The Institut Pasteur prepares the sets of 

 cultures for making this cheese, namely: 1, lactic acid bacteria; 



2, yeasts, Oidium lactis and Penicillium camemberti, and 3, 

 peptonizing micrococci which produce a reddish pigment. The 

 procedure with these cultures is as follows : The milk, which should 

 be pasteurized, is inoculated with the culture of lactic acid bac- 

 teria and ripened at 18 to 20 C. When ripe, Culture 2 is mixed 

 with the milk and the casein precipitated with rennet at 26 C. 

 Salt is then added and the curd placed in a dry room at 13 to 

 15 C. The cheeses are turned frequently until covered with a 

 layer of mold. They are then placed in ripening cellars at 7 

 to 8 or 10 to 12 C. At the lower temperature the process is 

 slower than at the higher one, but the product is of better quality. 

 The red peptonizing bacteria (Culture 3) are cultivated in milk, 

 and the rush mats which are placed under the cheese are soaked 



