Condensed Mii,k and Milk Powder 103 



the coils and jacket. Hot air is then passed into the milk. The 

 temperature of the air is regulated so as to keep the temperature of 

 the evaporating milk down to> 120 degrees P. on the start, and to 

 finish the evaporation between 90 and 100 degrees F. The air 

 blast is so introduced as to keep the milk along the heating surface 

 of the jacket and coils in circulation and, therefore, prevent largely 

 the baking of the milk on the heating surface. After the milk has 

 been evaporated to a certain degree of concentration, say 2:1, it is 

 transferred to the auxiliary evaporating tank where the condensa- 

 tion is completed. This transfer is not necessary, but is resorted 

 to solely as a convenience, in order to continue treatment of the re- 

 duced bulk of material in a smaller tank and leave the larger tank 

 free for treating a fresh batch of milk, and, further, because there 

 are no obstructing coils in the auxiliary tank, interfering with the 

 drawing off of the finished and thick condensed milk. In this pro- 

 cess, as now used, the milk is usually first separated and the skim 

 milk only is condensed. The cream is subsequently added to the 

 condensed skim milk. 



Advantages and Disadvantages of Campbell Process. — The 



initial cost of installing the necessary machinery is much less than 

 where vacuum evaporation is practiced. The low heat applied makes 

 it possible for the finished product to retain the properties of raw 

 milk, leaving the albumenoids and lime salts in their original and 

 easily digestible form. 



This process is applicable only in the manufacture of unsweet- 

 ened condensed milk. Unless subsequently sterilized, the product 

 will keep for a short time only. This process has at the present time 

 only very limited use. It can hardly be considered as an important 

 branch of the condensed milk industry. 



CHAPTER XV 



CONDENSED BUTTERMILK 



The value of buttermilk as a chicken feed is rapidly gaining 

 recognition. Buttermilk, similar to skim milk and whole milk, is a 

 highly satisfactory feed for fattening chickens. Its value is en- 

 hanced by the superior quality of the meat from buttermilk-fed 

 chickens. 



