260 UNSWEETENED ConpENSED Mirx Derrcrs 
prevent the more highly concentrated milk from becoming per- 
manently curdy. If, in order to increase the viscosity, the degree 
of concentration is carried so far that the sterilizing process has 
to be shortened, nothing is gained but much may be lost. It 
is obvious, therefore, that the degree of concentration does not 
furnish a practical basis for controlling fat separation. 
Effect of the Sterilizing Process.—Prolonged exposure of 
the evaporated milk to the sterilizing heat tends to so change the 
physical properties of the albuminoids, as to render the product 
more viscous. Within the limits of the necessary sterilizing heat, 
long exposure to moderate heat is more effective in this respect 
than short exposure to a high degree of heat. Since the greater 
viscosity tends to keep the fat globules from rising, the use of 
a prolonged sterilizing process, in which the heat is applied 
slowly, is more effective in preventing fat separation in the 
evaporated milk than a rapid, short process, in which the tem- 
perature used is very high. 
It should be understood from the discussion in previous 
chapters that, in regulating the process of sterilization, the pro- 
cessor should be governed by the condition and behavior of the 
milk and that on the one hand the degree and duration of heat 
should always be sufficient to insure absolute sterility of the 
product, while on the other he must guard against the formation 
of an unshakable curd.! 
Effect of Superheating.—The superheating of the milk be- 
fore sterilization and the stopping of the reel of the sterilizer 
as explained under “Sterilization,” also tend to so increase 
the viscosity of the evaporated milk as to minimize its tendency 
to separate its fat. But here again good judgment is required, 
otherwise there 1s danger of spontaneous thickening of the prod- 
uct after manufacture. 
Turning the Cans in Storage.—Many manufacturers, in an 
effort to avoid fat separation, have adopted the practice of turn- 
ing their goods in storage at regular intervals. ‘This operation 
naturally interferes with and retards the rising of the fat to the 
surface, as long as the goods remain in the factory. After they 
leave the factory this control must of necessity cease and if the 
1¥For detailed discussion see Chapter XI on “Sterilizing.” 
