74 BULLETIN 98, TJ. S. DEPARTMENT OF AGRICULTURE. 



as soon as the milk is received it is weighed and dumped into a vat 

 from which it runs over the cooler to the bottling machine or into 

 cans. Ice water or brine, or often a combination of the two, is cir- 

 culated through the pipes of the cooler; ice water being run through 

 the upper tubes and brine through the lower. The principal work, 

 therefore, of the receiving station is that of cooling and preparing 

 the milk for shipment. The lower the temperature of the milk, so 

 long as it is kept above the freezing point, the better. With the 

 present state of development of refrigerator cars used in the trans- 

 portation of milk, they can not be depended upon for lowering the 

 temperature to any great extent during transit; consequently the milk 

 should be thoroughly cooled before loading on the cars. Usually 

 several hours elapse between the time the milk is drawn from the 

 cow until it is loaded on board the cars, which makes it imperative 

 that it be precooled. 



The cooling takes placed early in the morning and late in the 

 afternoon, as the milk is received. The time required for cooling 

 seldom exceeds two hours for each period, making the total time 

 employed in cooling about four hours daily. Owing to the short 

 time in which the cooling is done the capacity of the refrigerating 

 apparatus is necessarily large for the amount of work required. It is 

 possible, however, to decrease the capacity of the plant by rmming 

 the machine a longer time and storing refrigeration in brine, which 

 can be held for quick action when needed. 



COOLING MILK IN BOTTLING PLANTS. 



Milk-bottling plants are usually located in cities or towns. The 

 milk is generally shipped in cans direct from the farms or receiving 

 stations, arriving at the bottling plants at a temperature of approxi- 

 mately 60° F. As soon as the milk is received at the city plant it is 

 cooled to a temperature of 45° or 50° F., bottled, and placed in a 

 refrigerated room, and held until the following morning, when it is 

 delivered to the consumer. As the temperature of the room is around 

 32° F., the milk will come out in the morning at 35° or 40° F. 



PASTEURIZING PLANTS. 



In those plants where the milk is pasteurized previous to cooling 

 the refrigeration required is, of course, considerably greater than in 

 raw-milk plants, where the temperature of the incoming milk is 

 simply reduced to 35° or 40° F. The amount of refrigeration required, 

 however, depends upon the pasteurizing equipment employed. 



There are in use at the present time two systems of pasteurization, 

 known as the "holder" and "flash" processes. 



The holder process consists in holding the milk or cream for about 

 30 minutes after it has been heated to the pasteurizing temperature 

 of 140° to 150° F., either in the same apparatus in which the pasteur- 



