Sweetened Condensed Milk — Striking 87 



boiling, loss can be avoided and the process can be continued in the 

 normal way. 



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

 completed, and from ten to twenty minutes further boiling usually 

 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 ofif entirely. 



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 con- 

 densed 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 den- 

 sity 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 con- 

 densed 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 on the propor- 

 tion of water evaporated, in which case it is obviously much higher 

 than when based on the amount of milk required to make one pound 

 of condensed milk, because the added cane sugar takes the place, of 



