EVAPORATED M1LK—CooLinec 129 
eurdy and unmarketable. In this case the cure would be more 
disastrous than the original defect. Great care must, therefore, 
be exercised, guarding against the use of excessive pressure that 
would injure the casein. Experiments have shown that a 
pressure of between one thousand and fifteen hundred pounds 
per square inch is sufficient to prevent fat separation and is 
practically harmless as far as its objectionable effect on the 
casein in the evaporated milk is concerned. 
The evaporated milk is run through the homogenizer hot, 
just as it comes from the vacuum pan or standardizing tank. If 
the evaporated milk were homogenized cold, the fat globules, 
instead of being subdivided would unite into butter granules, the 
milk would churn. The first pailful of milk passing through the 
machine should be returned to the supply tank, as on the start, 
the pressure is not uniform and homogenization is incomplete. 
The pistons, cylinders, valves and pipes of the homogenizer 
should be kept in sanitary condition. They are difficult to clean. 
After homogenizing, the machine should be kept in operation, 
running water through it, until most of the remnants of evapo- 
rated milk are rinsed out; then hot water containing some 
active alkali should be pumped through; this should be followed 
by clean hot water and steam. Unless this machine is kept 
scrupulously clean, it may become a dangerous source of con- 
tamination, infecting the evaporated milk with spore forms 
that are exceedingly resistant and which are liable to pass into 
the finished product alive. in spite of the sterilizing process, 
causing the goods to be a complete loss, due to subsequent 
fermentation. 
CHAPTER N. 
COOLING. 
In the cooling of the evaporated milk, no attention need be 
paid to sugar crystallization. In this class of goods there is 
plenty of water to keep the milk sugar in ready solution. The 
evaporated milk can, therefore, be cooled as rapidly as facilities 
permit. The cooling may be accomplished in similar ways as 
are used for cooling fresh milk. From the homogenizer the 
evaporated milk is run over a surface cooler, or cooling coil. Tt 
