PLAIN CONDENSED BULK MILK 163 



and thicken it, and it has the consistency of rich cream. It is 

 sold in 10-gallon milk cans to ice cream factories and in milk 

 bottles to the direct consumer. Plain condensed bulk milk is 

 not sterile, nor is it preserved by sucrose. Its keeping" quality 

 is similar to that of a high quality of pasteurized milk. 



Quality of Fresh Milk. The sweeter and purer the fresh 

 milk or skim milk, the better will be the quality of this product. 

 Old milk, or skim milk in which the acid development has made 

 considerable headway, tends to form a lumpy plain condensed 

 bulk milk. However, since this milk is not subjected to steriliz- 

 ing temperatures and is used up quickly after manufacture, the 

 quality of the fresh milk from which it is made, is not of such 

 magnitude as in the case of evaporated milk. 



Heating. In the manufacture of plain condensed bulk milk 

 the heating is accomplished much in the same manner as in the 

 case of sweetened condensed milk and evaporated milk. The 

 milk is usually heated by turning steam direct into it; though 

 many of the more efficient types of milk and cream pasteurizers 

 could be used to excellent advantage for this purpose. 



It is advisable, however, to heat this milk only to about 150 

 to 160 degrees F. in order to secure a nice "liver" (coagulum), 

 when it is superheated in the pan. If the milk is heated to the 

 boiling point in the forewarm>ers, it does not respond to the 

 superheating in the pan as satisfactorily. 



Condensing. The condensing of plain condensed bulk milk 

 is done in the vacuum in a similar manner as described under 

 evaporated milk, except that the evaporation is carried farther. 

 See also "Campbell Process" and "Condensing Milk by Continu- 

 ous Process." 



Superheating. AVhen the condensation is nearly completed 

 the milk in the pan is superheated. This is accomplished by 

 shutting off the steam to the jacket and coils, closing the valve 

 that regulates the water supply of the condenser, stopping the 

 vacuum pump and blowing steam direct into the milk in the pan, 

 for the purpose of swelling and thickening it. During this proc- 



