TESTS USED IN CHEESE-MAKING 437 



one milk to another and spoiling the test. The curd 

 is allowed to settle completely. When the whey has 

 been separating half an hour, the samples are exam- 

 ined for flavor by smelling, after which the whey 

 is carefully poured out of the jars and this is repeated 

 at intervals of 30 to 40 minutes for 8 hours or more. 

 Under the favorable conditions of temperature, similar 

 to those employed in cheese-making, the organisms 

 present develop readily and reveal their presence in 

 different characteristic ways. The jars are finally 

 opened, any whey present is drained off, and the fol- 

 lowing tests are applied : ( i ) The curd is cut into two 

 pieces. The curd will be solid and free from holes 

 on the cut surfaces, if the milk is not tainted. If it 

 is spongy and full of holes, it contains those undesir- 

 able organisms that produce gases in the curd and in- 

 jure it for cheese-making, showing in the form of 

 ''floating curds" and ''huffy" cheese. The holes are 

 usually small, their common name being "pin-holes." 

 (2) The curd is examined with reference to any 

 marked disagreeable odors that may be present. Some 

 undesirable organisms reveal their presence by smell 

 without making spongy curd. This may, perhaps, be 

 best perceived by smelling of a freshly cut surface 

 of the curd. Offensive odors are, of course^ an unde- 

 sirable indication. Special apparatus for perform- 

 ing the test is furnished by dairy-supply houses, but 

 pint fruit- jars and other home-made appliances will 

 answer satisfactorily. 



By this method one can learn what particular lot 

 of milk among several is responsible for undesirable 

 fermentations. Moreover, having traced the source of 

 contamination to a single herd of cows, it is easily 



