160 EVAPORATED M1L.K—SHAKING 
tion, the lower the temperature required to precipitate the 
casein. It seems that the concentration of the milk intensifies 
the properties of milk to coagulate when subjected to heat. This 
factor is probably in part at least due to the increase of the per 
cent of lactic acid in the evaporated milk, due to the concentra- 
tion. If the fresh milk contains .17 per cent lactic acid, a con- 
centration of two and one-fourth parts of fresh milk to one part 
of evaporated milk causes the evaporated milk to contain .17 
« 2.25 = 38 per cent lactic acid. With this amount of acid 
acting en the casein, it is not difficult to understand why a coag- 
ulum is often formed in the 
sterilizer. \While the formation 
of this coagulum may be partly 
avoided, under certain condi- 
tions it appears in every fac- 
tory and there are more batch- 
es, especially in summer, that 
come from the sterilizer coag- Fig. 68. Evaporated milk shaker 
: Courtesy of Arthur Harris & Co. 
ulated than otherwise. 
In this condition the product is not marketable. Some means 
must be provided, therefore, to break up this curd and reduce 
the contents of the cans to a smooth, homogeneous and creamy 
body. For this purpose a mechanical shaker is used. 
Method of Shaking.—The shaker consists of one or more 
heavy iron boxes, or iron crates made of black iron pipes. These 
boxes are at- 
tached to an 
eccentric. The 
trays filled 
with evaporat- 
ed milk cans 
are fora ly 
wedged into 
these boxes. 
When the 
shaker is in 
operation, the 
Fig. 69. Evaporated milk shaker 
Courtesy of The Engineering Co. 
cans are shaken back and forth violently, causing the curd in 
the cans to be broken up. 
