58 Factory SANTTATION 
the milk as soon as it arrives and of holding it at a low tempera- 
ture until ready for heating and condensing. This has led to 
diverse practices, such as running the milk over a surface coil 
cooler into a jacketed tank, or cooling it by running it into a 
large tank equipped with cold air blowers, or cooling the milk in 
large vats equipped with revolving coils, ete. 
One of the later methods for refrigerating the milk consists 
of the use of large, usually circular, glass enameled steel tanks. 
‘These tanks are completely surrounded on their sides and bottom 
by a cold water or brine jacket and are equipped with a milk 
distributing device that causes the infowing milk to be sprayed 
by gravity against the top of the sides of the tank and to per- 
colate in a thin laver down the sides. In this manner the cooling 
is instantaneous, the entire sides of the tank being surrounded 
by the cooling medium. It is aimed to cool the milk to about 
40 to 45 degrees F. and to hold it at this temperature until ready 
for manufacture. 
‘These glass enameled tanks have many advantages; they 
minimize the initial cost of the necessary equipment, reducing 
the number of costly vacuum pans, and forewarmers, required; 
they cut down labor cost, because they reduce the equipment to 
fewer pieces to operate and to clean; they are of such construc- 
tion that they are easily and quickly cleaned and readily kept in 
proper sanitary condition, the smooth and pore-free enamel vields 
more readily to the brush than copper surfaces; they avoid all 
possibility of chemical action of the milk on metal and, therefore, 
are a reliable safeguard against the development of metallic 
flavor in the milk. 
The use of these large holding tanks also facilitates the 
standardization of the milk for fat and solids not fat. For detailed 
directions on standardizing see Chapter NNIN, 
