462 MANUAL OF MILK PRODUCTS 



the milk, and the season of the year. The sterilizing process oc- 

 cupies from one to two hours, varying with the temperature 

 applied and rapidity of heating. Before the cans leave the 

 sterilizer they are cooled sufficiently so they can be handled 

 conveniently. 



From the sterilizer the cans pass into the shaker, a machine 

 consisting of one or more heavy iron boxes into which the cans 

 are wedged and which move back and forth on an eccentric, 

 subjecting the cans and their contents to violent shaking, for 

 the purpose of giving the evaporated milk a smooth and homo- 

 geneous body. 



EFFECT OF CONCENTRATION UPON ACIDITY (Hunziker) 1 



The action of heat on the properties of milk is intensified by 

 the concentration of the milk. The greater the ratio of con- 

 centration, the more intense is the action of heat on milk. This 

 fact can be demonstrated mathematically in the case of the 

 acidity of milk ; milk received at the factory may contain, say 

 .17 percent acid. If the milk is condensed 2 : 1, the condensed 

 milk will contain approximately .17 X 2, or .34, per cent acid. 

 If the ratio of concentration is 2.5 : 1, the condensed milk will 

 contain .17 X 2.5, or .425, per cent acid. This increase in the 

 per cent of acid of the 2.5 : 1 condensed milk is sufficient in most 

 cases to cause the same sterilizing temperature to curdle such 

 milk into a firm and hard curd that cannot be shaken out 

 mechanically. 



The actual relation of the per cent of acid to the degree of 

 concentration and its effect on the physical condition of the 

 evaporated milk is clearly shown in the following table. This 

 table shows the results of evaporating fresh milk to different 

 degrees of concentration. 



1 Ind. Bui. 143. 



