130 ISVAPORATED M1LK—CooLinc 
is advisable to cover the coils with a jacket of galvanized iron, 
tin or copper, so as to avoid undue contamination of the milk 
from dust, flies, and other undesirable agents. In sor-e con- 
denseries the hot evap- 
orated milk is forced 
through double pipes, 
cold water passing be- 
tween the inner and 
outer pipes, or the coils 
through which the milk 
passes are submerged 
in a tank of cold water. 
The only objection to 
this system is that the 
pipes are more difficult 
to clean than in the 
case of an open surface 
cooler. Where this sys- 
tem is used, the pipes 
should be equipped 
Fig. 52. Surface cooler for evaporated milk 
; : Rai Courtesy of Davis-Watkins Dairymen’s Mfg. Co. 
with sanitary fittings 
so that they can be readily swabbed out from both ends. In 
other factories, the evaporated milk is cooled in revolving cans 
with stationary paddles, similar as described and used for 
sweetened condensed milk, with the exception that cold water 
is run into the cooling tank at once. In still other factories the 
cooling is done in vats or tanks by means of revolving coils 
which carry the cooling medium. If the evaporated milk is’ not 
homogenized, it should be cooled as soon as it leaves the vacu- 
um pan. 
Holding Tanks.—The cooling and holding of evaporated 
milk may be accomplished in the same series of equipment as 
described and illustrated under cooling of sweetened condensed 
milk, Fig. 38. The tanks for holding this product are preferably 
jacketed, so as to make possible the circulation of cold water 
or brine, in case the evaporated milk must be held for a consider- 
able number of hours in the holding tank. Some of these tanks 
are equipped with propellers eccentrically located, facilitating 
