Bacteria and Cheese Making. 179 



Cases of acute poisoning arising from the ingestion of 

 cheese are not infrequently reported; similar instances 

 result from the use of ice cream. In both cases it is be- 

 lieved that poisonous products have been formed by 

 bacteria, probably by some of the putrefactive forms. 



From what has been said with reference to the ab- 

 normal fermentations of cheese, it will be seen that they 

 are always due to the lack of acid-forming bacteria, or 

 to their partial replacement by other types. In order 

 to prevent such troubles, it is necessary to insure that 

 the milk has been produced under clean conditions, from 

 healthy cows, and has been handled in such a manner 

 as to reach the maker in as sweet and fresh condition as 

 possible. The maker can, by the use of proper starters, 

 control the kinds of bacteria essential for the ripening 

 process. A well trained maker should be able to pre- 

 pare from such milk a uniform product of the highest 

 quality. The effort of cheese makers at the present time 

 is to handle milk of more or less objectionable quality 

 so as to secure from it as good cheese as is possible. But 

 cheese is so sensitive as to character of milk used that 

 greater effort should be spent in securing an improved 

 supply. 



Moldy cheese. In the case of the cheddar cheese and 

 other types of hard cheese, it is essential that their sur- 

 faces be kept clean, and not discolored by the growth of 

 molds, which find favorable conditions for growth on 

 the surface of the cheese in the moist atmosphere of the 

 curing room. The molding of cheddar cheese can be 

 prevented by covering the cheese with a layer of paraffin 

 which stops the development of the mold spores, by shut- 

 ing off the necessary supply of oxygen. For this pur- 



