66 Condensed Milk and MiEk Powder 



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 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 :i, 

 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 add- 

 ed to every one hundred pounds of fresh milk. 



Methods. — To know just when the proper degree of concen- 

 tration has been reached, is difficult and requires experience. It is 

 here where the processor can easily make or lose his wages. There 

 are various indications reminding the observant processor that the 

 milk in the retort is nearly "done," viz., time consumed for conden- 

 sing, time elapsed since all the milk has been "drawn up," amount 

 of condensed milk left in the pan, and, most of all, the appearance 

 and behavior of the boiling milk itself. Milk that has been suffic- 

 iently condensed assumes a glossy, glistening luster, it boils over 

 from the periphery towards the center, forming a small nucleus or 

 puddle of foam in the center of the pan. An experienced and ob- 



