244 BACTERIA IN CHEESE MAKING. 



developing the proper ripening of the cheese and of prevent- 

 ing the growth of undesirable bacteria. 



Other Types of Abnormal Ripening. There are no other 

 types of abnormal ripening that produce so much trouble as 

 swelled cheese, but a few others may be mentioned. Occa- 

 sionally cheese develops such a strong bitter taste as to be 

 practically worthless. The fact that bacteria have been 

 proved capable of developing a bitter taste in the milk has 

 suggested that they are also the cause of bitter cheese. A 

 few instances only have been studied sufficiently to disclose 

 the cause. In one case the trouble was found to be produced 

 by a definite species of bacterium closely related to one 

 previously found in bitter milk (266). The organism, 

 named M. casei aniari, developed a bitter taste in milk in two 

 days, and when inoculated into milk which was subsequently 

 made into cheese developed the typical character of the bitter 

 cheese. In another series of cases (273) a bitterness was 

 proved to be produced by a yeast which was widely dis- 

 tributed and found its way into the milk cans which were left 

 standing open by roadsides, or under trees or near barnyards. 

 Sterilizing of the cans and utensils, greater care in handling 

 the milk, and increased cleanliness are the only efficient 

 remedies for such a condition. 



A common fault of cheese ripening is a putrefaction of 

 the product. This trouble occurs especially in soft cheeses, 

 doubtless because of the larger amount of water. It seems 

 strange that putrefaction does not occur in the soft cheeses 

 more readily than it does, for these cheeses are moist and 

 would seem to offer most excellent material for the growth of 

 putrefactive organisms. Under the conditions of ordinary 

 ripening putrefaction is checked and is not noticeable ; but 

 sometimes the cheese, instead of ripening normally, decays 

 into a soft, vile-smelling mass of slime. This is due, doubt- 

 less, to the development of bacteria, inasmuch as bacteria 

 are the only known cause of such putrefactive changes. The 



