TESTING xMlLK AND CREAM. 29 



1. Not mixing acid and milk at oncu after acid 

 is added to milk. 



2. Not having- proper temperature during testing. 



3. Too low speed of tester, combined with weak 

 acid. 



4. Insufficient mixing and unclean acid. 



(c) Causes of black flakes and black fat column. 



1. Too strong acid. 



2. Too much acid. 



3. Too high temperature of milk or acid or both. 



4. Not mixing acid and milk soon enough after 

 adding acid. 



30. The mixing of cream and acid. The addition 

 of the acid to the cream, and the mixing of the 

 same, is carried, on in the same manner as outlined 

 for testing whole milk. When pouring the acid into 

 the cream test bottle, the bottle must be held in such 

 a way as to wash any cream adhering to the neck 

 of the bottle down into the bulb of the bottle. Im- 

 mediate mixing is absolutely necessary. If not 

 mixed immediately the acid may act upon part of 

 the cream and burn part of the butter fat, which 

 will appear in the fat column when the testing is 

 done in flocules or tlakes resembling charred fat. 

 Delay in mixing also causes the acid to act unevenly 

 upon the casein and thereby may produce white 

 flakes, which usually appear at the bottom of the 

 fat column. In case delay in mixing the cream with 

 the acid does not produce either of those defects, it 

 may produce a mottled column of fat. This is evi- 

 dent in the lower portion of the fat column by the 

 appearance of a brownish or yellowish brown streak. 



