190 Dairy Bacteriology. 



It is peculiar that some of the organisms that are able to 

 produce hitter products in milk do not retain this property 

 when the milk is worked up into cheese. 



Putrid or rotten Cheese. Sometimes cheese undergoes 

 a putrefactive decomposition in which the texture is pro- 

 foundly modified and various foul smelling gases are 

 evolved. These often hegin on the exterior as small cir- 

 cumscrihed spots that slowly extend into the cheese, chang- 

 ing the casein into a soft slimy mass. Then, again, the 

 interior of the cheese undergoes this slimy decomposition. 

 The soft varieties are more prone toward this fermentation 

 than the hard, although the firm cheeses are by no means 

 exempt from the trouble. The " Verlaufen " or " running" 

 of lim burger cheese is a fermentation allied to this. It is 

 where the inside of the cheese breaks down into a soft 

 semi-fluid mass. In severe cases, the rind may even be 

 ruptured, in which case the whole interior of the cheese 

 flows out as a thick slimy mass, having sometimes a putrid 

 odor. The conditions favoring this putrid decomposition 

 are usually associated with an excess of moisture, and an 

 abnormally low ripening temperature. 



Rusty Spot. This name is applied to the development 

 of small yellowish-red or orange spots that are formed 

 sometimes throughout the whole mass of cheddar cheese. 

 A close inspection shows the colored points to be located 

 along the edges of the curd particles. According to Hard- 

 ing, 1 this trouble is most common in spring and fall. The 

 cause of the difficulty has been traced by Connell 8 to the 

 development of a chromogenic bacterium, Bacillus ruden- 

 sis. The organism can be most readily isolated on a po- 



i Bull. 183, N. Y. (Geneva) Expt. Stat., Dec. 1900. 

 'Connell, Bull. Canadian Dept. of Agr., 1897. 



