96 SWEETENED CONDENSED MII.K STRIKING 



By the time all the milk is in the pan, condensation is nearly 

 completed, and from ten to twenty minutes further boiling usu- 

 ally gives the milk the desired density. Toward the end of the 

 .process the steam pressure in jacket and coils should be reduced 

 to about five pounds or less. When the milk approaches the 

 desired density, it is comparatively heavy and viscous and boils 

 less vigorously. It therefore is more directly exposed to the 

 heating surface. In the case of excessive steam pressure, its 

 quality is jeopardized. If the batch is small so that the level 

 of the milk drops below some of the coils, steam to the exposed 

 coils should be turned off entirelv. 



CHAPTER VI. 



STRIKING OR FINISHING THE BATCH. 



Definition. When the boiling milk in the vacuum pan ap- 

 proaches the desired degree of concentration, the batch is 

 "struck." The term "striking" is applied to the operation of 

 sampling the condensed milk and testing the sample for density. 

 This term very probably referred, originally, to the meaning of 

 "striking the batch right," that is, stopping the process at the 

 proper time, or when the milk is neither too thick nor too thin. 

 It then expressed the result of the operation, while now it is 

 used to mean the operation itself. 



Ratio of Concentration. Sweetened condensed milk intended 

 for canned goods has a specific gravity of 1.28 to 1.30. This 

 density is reached usually when the ratio of concentration is 

 about 2.5:1, i. e., 2.5 parts of fresh milk are condensed to one 

 part of condensed milk, assuming that about sixteen pounds of 

 sucrose have been added to every one hundred pounds of fresh 

 milk. 



Occasionally the ratio of concentration is based qn the pro- 

 portion of water evaporated, in which case it is obviously much 

 higher than when based 011 the amount of milk required to make 

 one pound of condensed milk, because the added cane sugar 

 takes the place of its own weight of water, and thereby acts as* 

 a diluent of the condensed milk. Thus let us assume that 16 



