SWEETENED CONDENSED M1ILK—COOLING 109 
The pressure required to pump the sweetened condensed 
milk through the cooling coil and up into the holding tanks 
varies from about 800 to 1200 pounds, and the pump used for 
this purpose must be strong enough to develop a pressure of 
at least 2,000 pounds, which may be required to start the flow 
through the coil after the milk has stood idle for some time and 
has become chilled. 
This method, in addition to its labor-saving feature, and 
to its efficiency in avoiding sandy and settled condensed milk, 
has the further important advantage, that the product is pro- 
tected against contamination with bacteria, mold, and other im- 
purities from the air. etc., the product being under seal until 
it reaches the filling machine, or until it is packed into barrels 
in the case of bulk goods. This method, therefore, should be 
particularly adapted for efforts to produce an article that does 
not develop “buttons” with age. See also Chapter on ‘Defects 
of Sweetened Condensed Milk.” 
The chief criticism that may be raised against this method 
lies in the question of cleaning the cooling coil. From the 
standpoint of bacterial contamination it may safely be said, 
however, that the danger of such contamination is remote. After 
the product of one day’s make has passed through the coil, the 
coil is sealed by valves and there is no reason to doubt that 
the condensed milk remaining in the coil till next day’s opera- 
tion, is not just as well protected against all contaminating 
influences, as if it were sealed in tin cans. It is advisable, how- 
ever, to completely empty and rinse and steam the submerged 
coil at regular intervals of say once per week. This is especially 
desirable in the case of a copper coil, in order to guard against 
an excessive accumulation of copper salts which would tend 
to lend the product a metallic flavor and te jeopardize its whole- 
someness. In the case of a black iron coil, sand-blasted on inside, 
the effect of the action of the acid and sugar of the milk is 
negligible. However, when not filled with condensed milk the 
iron coil should be kept filled with clean water to prevent exces- 
sive rusting. 
