170 Condensed Mh,k and Milk Powder 



ficient to insure absolute sterility of the product, while on the other 

 he must guard against the formation of an unshakable curd. 1 



Effect of Superheating. — The viscosity of the evaporated milk 

 may also be slightly increased and its sensitiveness towards the 

 sterilizing heat lessened by superheating it in the vacuum pan. 



Turning the Cans in Storage. — Many manufacturers, in an 

 effort to avoid fat separation, have adopted the practice of turning 

 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 evaporated milk, 

 owing to the process of manufacture and the condition of the 

 product, is destined to separate its fat, the turning of the cases, 

 while at the factory, cannot permanently prevent separation. Where 

 the goods are consumed immediately after they leave the factory, 

 this practice may serve the purpose; but, since the large bulk of 

 evaporated milk manufactured, is exposed to prolonged storage, its 

 advantage is very limited. 



Effect of Homogenizing. — Under average conditions careful 

 attention to the precautions above discussed will greatly minimize 

 and often prevent fat separation. At best, however, much of the 

 evaporated milk on the market shows signs of separation after sixty 

 to ninety days and some of it even after two weeks, for the funda- 

 mental cause of separation, the difference in gravity between the 

 fat globules and the rest of the milk constituents, is still present; 

 then again, under less favorable conditions, even the above precau- 

 tions may not prove adequate to keep the fat from separating. 



The introduction of any agent or process, therefore, capable of 

 permanently removing this fundamental cause, must prove a lasting 

 benefit to the manufacturer of evaporated milk. This agent has 

 been found in the homogenizer. The homogenizer makes it possible 

 to divide the fat globules so finely, that their buoyancy or gravity 

 force is not great enough to overcome the resistance of the sur- 

 rounding liquid. They are unable to rise to the surface, but remain 

 in homogeneous emulsion. 



The chief objection to the use of the homogenizer is its effect 

 on the casein of the milk. Beyond certain limits of pressure it so 



1 For detailed discussion see Chapter XII on "Sterilizing," p. 93 



