EvapPoratéD MILK— SHAKING 159 
be cooled to a low temperature. All abuses of milk along these 
and similar lines are bound to cause trouble in the sterilizer, 
which is avoidable and unnecessary. 
Finally there are factors which are not under control but 
which also exert a very marked influence on the behavior of 
the product toward sterilizing heat at times. These are invyari- 
ably associated with changes in the peried of lactation, changes 
in feed and climatic conditions and their effect on the amount and 
proportion of the protein and ash constituents of milk, as ex- 
plained in Chapter NNIIT. “Defective Evaporated Milk, Lumps 
of Curd.” These conditions are not only not controllable, but 
their effect on the milk is not determinable by any now known 
practical method of analyses. 
Proper attention to the controllable conditions will go far 
in making unnecessary the use of bicarbonate in evaporated 
milk and will at least confine its use, when necessary, to very 
small amounts. When these conditions have been conscientiously 
taken care of and, in spite of these precautions, certain batches of 
milk, because of the above named effect of uncontrollable fac- 
tors, require the use of bicarbcnate in order to insure safe ster- 
ilization and to avoid loss, then the emergency justifies and 
sound judgment and business efficiency demand recourse to 
methods that the helping hand of science has made available, 
so long as these methods do not impair the wholesomeness and 
food value of the product, although their ethics, in principle at 
least, cannot be approved for general practice. See also “Effect 
of Relation of Mineral Constituents of Milk.” Chapter NXNIIT, 
“Defective Evaporated Milk.” 
SHAKING. 
Purpose.—The purpose of shaking the evaporated milk is 
to mechanically break down the curd that may have been formed 
in the process of sterilization and to give the contents of the cans 
a smooth and homogeneous body. 
The high temperatures to which the evaporated milk is sub- 
jected in the sterilizer have a tendency to coagulate the casein. 
In the case of normal, fresh milk the casein coagulates at a tem- 
perature of 269 degrees F. In the evaporated milk, made from 
perfectly normal and sweet, fresh milk, the casein curdles at 
much lower temperatures, and the higher the ratio of concentra- 
