176 Dairy Bacteriology. 



proved. It was formerly supposed that the lactic bac- 

 teria had an injurious effect on the gas-forming organ- 

 isms. There is no good reason to believe that 'this is 

 the case, but that both grow in the milk and cheese, but 

 since only a certain amount of acid can be produced, it 

 is important to have as much of it formed by the lactic 

 bacteria as possible, since the amount of injurious prod- 

 ucts in the cheese will thus be limited. 



The gas formed in the curd before the cheese is put 

 to press can be gotten rid of by proper manipulation of 

 the curd. While this treatment may improve the ap- 

 pearance of the cheese, it does not eliminate the sub- 

 stances that impart to the cheese undesirable qualities. 



Gassy curds have also been treated by washing the 

 curd with cold water. Care must be taken in applying 

 this method for the removal of too much of the sugar 

 and acid from the curd by the washing will permit the 

 growth of injurious forms of bacteria. The addition of 

 salt or of saltpeter has also been made to the milk in 

 order to overcome gassy conditions in the milk. In the 

 handling of gassy milk, the usual practice has been to 

 develop a larger amount of acid before drawing the whey 

 than in the case of good milk. This was done with the 

 idea that a-cid suppressed gas formation. It has been 

 shown previously that this is not the case. It has also 

 been shown by Doane that the development of too much 

 acid before drawing the whey is likely to result in un- 

 desirable flavors, producing what is known as "high- 

 acid'' or "sour" cheese. 



The gas-forming bacteria grow best at high tempera- 

 tures; hence, cheese kept under these conditions are more 

 likely to be affected by this trouble than are those kept 

 at lower temperatures. 



