502 MICROBIOLOGY OF MILK AND MILK PRODUCTS 



organism of this group and a mycoderma are used with success in 

 Switzerland for the inoculation of the whey in which the rennet is to be 

 soaked. The exact role of this form of lactic organism is not known; de 

 Freudenreich considered them to be concerned in the proteolysis of 

 the paracasein, since he had found that the content of sterile milk in 

 soluble nitrogen increased when inoculated with the organism. It has 

 been found possible by Rogers and his associates to employ commercial 

 rennet and pure cultures of organisms of the Bact. bulgaricum group 

 in the making of Swiss cheese. It has also been found advantageous to 

 add to the milk a small amount of a culture of the eye-forming organ- 

 ism. It seems probable that the use of these pure cultures will result 

 in a greater uniformity of the product than it has been possible to 

 attain by following the empirical methods commonly used. It is 

 probable that the formation of eyes and the flavoring compounds are 

 due, in part at least, to the same factors. 



In the other kinds of cheeses to be described, the r61e of the acid- 

 forming bacteria is similar, if not identical, to their r61e in Cheddar 

 cheese, i.e., in activating the pepsin of the rennet and in preventing 

 the growth of putrefactive bacteria. The factors concerned in flavor 

 development are different. 



ROQUEFORT CHEESE. This cheese, which is prepared almost 

 exclusively in the Department of Aveyron in southern France, is made 

 from sheep's milk. Its most striking characteristic is the marbled 

 or mottled appearance of the interior, due to the growth of a mold, 

 Penicillium roqueforti, Thorn. The curd is inoculated with the mold, 

 when it is placed in the press, by sprinkling the curd with bread crumbs 

 on which the mold has grown. The growth and sporulation of the 

 mold in the interior of the cheese are favored by piercing it with 

 small needles, thus admitting air. The characteristic flavor is due, 

 partially at least, to the mold. 



This cheese is cured in caves having a temperature below 15. 

 The fermentative processes are apparently closely dependent on the 

 moisture and temperature conditions of the curing room. This 

 emphasizes the importance of biological factors in the ripening process. 



GORGONZOLA CHEESE, prepared in Italy from cow's milk, and 

 STILTON CHEESE, made in England are similar to Roquefort in 

 appearance and contain the same mold Penicillium roqueforti. 



CAMEMBERT CHEESE. The soft cheeses are best represented by 



