136 EVAPORATED MILK STERILIZING 



fact that the vent hole or pin hole filler operates by gravity, as 

 to both, the empty cans and the inflowing evaporated milk, re- 

 duces the human and mechanical error to the minimum, once the 

 machine is set for operation. 



The acknowledged advantages of the venthole filler have 

 made its general adoption and use rapid and it is estimated that 

 today over 90 per cent of the American evaporated milk is 

 being canned by this type of filling machine. 



CHAPTER XL 



STERILIZING. 



The sealed cans are now ready for the sterilizer. If they 

 cannot be sterilized within an hour or two they should be sub- 

 merged in ice water or placed in a refrigerating room until the 

 sterilizer is ready for them.- This precaution is especially ad- 

 visable in summer. 



Purpose of Sterilization. The chief purpose of subjecting 

 the evaporated milk to the sterilizing process is to kill all germ 

 life and, therefore preserve the product permanently. When 

 the hermetically sealed cans come from the sealing room, their 

 contents are not sterile. The only means to preserve this milk 

 is to subject it to temperatures high enough to kill all forms 

 of ferments, organized and unorganized, vegetative cells and 

 spores. The success of the manufacture of this product depends 

 to a large extent on the process of sterilization. 



Aside from this, the manufacturer aims to gain another com- 

 mercially important condition, namely, to prevent the separation 

 of the butter fat. Before sterilization, there is nothing to prevent 

 the fat from separating out in the evaporated milk and from 

 churning in transportation, unless the evaporated milk was 

 homogenized. The sterilizing process helps to so change 

 the physical properties of the milk, that this tendency of the 

 fat to separate is greatly minimized. The sterilizing tem- 

 peratures used, further lend to the evaporated milk a creamy 

 consistency and yellowish color, giving the product a semblance 

 of richness, 



