136 EVAPORATED M1LK—S'YERILIZING 
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. 
Cuarter XI. 
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. ‘lhe 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 vellowish color, giving the product a semblance 
of richness, 
