58 FACTORY SANITATION 



'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, etc. 



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 inflowing milk to be sprayed 

 by gravity against the top of the sides of the tank and to per- 

 colate in a thin layer 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 yields 

 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 XXIX. 



