PLarn 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 tothe 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 aiter manufacture, the 
quality of the fresh milk from which it is made, 1s 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 forewarmers, 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.—When 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- 
