96 SWEETENED CONDENSED M1LK—S?TrIKING 
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 entirely. 
Cuapter VI. 
STRIKING OR FINISHING THE BATCH. 
Definition.—\Vhen the boiling milk in the vacuum pan ap- 
proaches the desired degree of concentration, the batch is 
“struck.”’ The term ‘ 
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 
‘striking’ is applied to the operation of 
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, 1. 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 on the pro- 
portion 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 its own weight of water, and thereby acts ag 
a diluent of the condensed milk. Thus let us assume that 16 
