SOUR OR CURDLED MILK. 



387 



PROBLEM VI. To determine reasons for milk being sour or 

 curdled. 



Example a. The acidity was 17-5, and the cream in clots. 

 The analytical figures were : 



Specific gravity, 

 Total solids, 

 Fat, . 

 Ash, . 



Solids not fat, 

 Soluble albumin, 

 Taste, 



1-0333 



12-73 percent. 

 3-56 



0-76 

 9-17 

 none, 

 boiled. 



The milk had been boiled and the cream allowed to rise and 

 clot, giving the milk a curdled appearance. 

 Example b. The milk was curdled, and the whey was 



Acidity, 

 Total solids, 

 Fat, . 

 Ash, . 

 Solids not fat, 



43-1 



6-25 per cent. 

 1-05 

 0-48 

 5-20 



From the low percentage of solids not fat and ash of the whey, 

 it was concluded that about 15 per cent, of water had been 

 added, and there was some probability that this water con- 

 tained an acid. It may also have been watered milk which has 

 gone sour. 



Example c. The milk was curdled and the whey analysed. 



The analytical figures were : 



Acidity, . 35-2 



Total solids, 

 Fat, . 

 Ash, . 

 Solids not fat, 



7-46 per cent. 



0-88 



0-60 



6-58 



It was concluded from the normal percentage of solids not fat 

 and ash of the whey, that nothing had been added and that the 

 milk had become sour by natural causes. 



Example d. The milk was curdled and the whey analysed. 

 It was slightly bitter and gave a pink biuret reaction. 



The analytical figures were : 



Acidity, . 20 -8 a 



Total solids, 

 Fat, . 

 Ash, . 

 Solids not fat, 



11-13 per cent. 

 3-03 

 0-69 

 8-10 



The alkalinity of the ash to phenol- phthalein was equal to 

 0-025 per cent. Na 2 C0 3 . 



