[ 6 45 ] 



with milk. Lard and vegetable oils are deficient in these 

 volatile acids, and this fact helps the detection of adulteration 

 of butter and ghee. 



1.116. The albuminoids of milk consist of casein and al- 

 bumin. The former is separated out by rennet but not the 

 latter, while the latter is separated out by boiling. In shar 

 we have butter and albumin, while in cheese we have butter 

 and casein. In colostrum albumin greatly preponderates, so 

 that it coagulates on boiling. In ordinary cow's milk, -?, of 

 the albuminoids is albumin and f is casein. 



1.117. The souring of milk is caused by Bacillus lactis. 

 If this bacillus can be excluded by sterilization and preserva- 

 tion in air-tight vessels, the milk can be kept sweet for an 

 indefinite period. There is a future for the sterilized milk 

 trade in India. The bacterium acts on the lactose of the 

 milk converting it into lactic acid. The acid acts on the 

 casein and precipitates it, which causes the curdling of the 

 milk. Rennet which is also a ferment acts on the casein at a 

 moderately high temperature and precipitates the coagulated 

 casein. But the production of lactic acid is not necessarily 

 effected by the addition of rennet nor is such production the 

 causfi of coagulation in cheese making. The addition of 

 rennet however turns the milk sour, other acids being gener- 

 ated. Any acid except carbonic acid, will coagulate milk, i.e. 

 cause the casein and the fat entangled in it to precipitate. 



1.118. There are more than one rapid process in use 

 for determination of the richness of milk. The old lacto- 

 meter test is useless, as skimming the butter increases the 

 specific gravity of milk and an addition of watef lowers this 

 specific gravity. A dishonest dealer with the help of a 

 lactometer can easily remove the fat by the rapid centrifugal 

 process and then by addition of water bring up the specific 

 gravity to 1*031 or 1-030. 



1.119. The lactocrite methods of testing milk are not 

 very satisfactory either. The idea in all these methods (e.g. 



