;i8 THE HANDBOOK FOR PRACTICAL FARMERS 



COOLING MILK ON THE FARM 



Cooling milk and cream x^i'omjDtly and properly Avould pre- 

 vent, to a large extent, the enormous losses which are occasioned 

 by the souring of these products before they reach the market. 

 All milk contains bacteria. These bacteria multiply rapidly at 

 temperatures above fifty degrees F. No matter how carefully 

 the milk has been produced, if it is not cooled innnediately and 

 kept cold, bacteria will develop and cause it to sour. 



Surface cooler or aerator. — To obtain rapid and economical 

 cooling, the milk or cream should first be run over a surface 

 cooler. Best results Avill be obtained if each cow's milk is cooled 

 immediately after milking, instead of waiting until all the milk 

 is drawn. This will save considerable time, as all except the last 



pail of milk will have passed 

 over the cooler by the time 

 the last cow is milked. While 

 most surface coolers require 

 running water, some of the 

 simpler coolers are fitted with 

 a tank, in which either ice Ava- 

 ter or running water can be 

 used. If cold Avater is avail- 

 able, the temperature of warm 

 milk may be lowered from 

 twenty-five to thirty-five de- 

 grees F., or very close to the 

 temperature of water. Pre- 

 cooling in this manner saves 

 both time and ice. From ten 

 to fifteen gallons of water are 

 required to lower the temperature of one gallon of milk to the 

 temperature of the water. 



Types of coolers. — A simple t^^pe of surface cooler is shown 

 in figure 168. The milk is poured into the upper bowl, which has 

 a row of small holes around the outer edge of the bottom. The 

 milk runs through these holes on to the surface of the conical 

 tank which contains the water. As the milk coming down in fine 

 streams hits the conical surface, it spreads into a thin film and 

 is quickly cooled as it passes over the cold surface. Either run- 

 ning water or ice and Avater may be used Avith this type of cooler. 

 If ice water is used, the contents of the tank should be stirred 

 frequently with an agitator, to keep a supply of cold AA^ater near 



168. — Milk cooler and aerator. 



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