190 



PASTEURIZATION 



vanized iron or tinned copper vat equipped with a revolving 

 copper coil or disc, through which hot water is circulated to 

 raise the temperature of the cream. The forewarmer should be 

 preferably of "low-down" construction so as to facilitate the 

 "dumping" of the cans. 



If the cream consists of part sweet and part sour cream or 

 if the acidity of different lots of cream in the forewarmer differs 

 materially, it is advisable to hold it in the forewarmer for about 

 thirty minutes or longer, to make the entire batch uniform in 

 acidity. If this is not done a tough, rubbery curd is prone to 

 form in the pasteurizer, which clogs the machine and the strain- 

 ers and causes excessive loss of fat in the buttermilk. 



The formation of this curd is due to the fact that the acid 

 in the sour cream acts intensely on the curd in the less sour 

 or sweet cream in the presence of pasteurizing heat. This can 

 be avoided by holding the mixed cream in the forewarmer long 

 enough to allow the acid in the sour cream to act on the curd, 

 in the sweet cream at about 90 degrees F. At this temperature 

 this action is less intense and the curd precipitates in the usual 

 and normal way. 



Tig. 27. Parringrton Junior pasteurizer 

 Courtesy Creamery Package Mfg. Co, 



