UNSWEETENED CONDENSED MiLk DEFECTS 257 
sterilizer. The homogenizing pressure should be kept down to 
one thousand to fifteen hundred pounds. 
Effect of Addition of Bicarbonate of Soda.—As shown in 
Chapter XI on “Sterilizing” the addition to the evaporated milk 
of bicarbonate of soda diminishes the viscosity and tendency to 
curdle in most cases. 
This is due to the fact, that in most cases, the coagulation 
is due to an excess of calcium and magnesium, which lowers the 
stability of the casein. he addition of carbonates in the form 
of bicarbonate of soda reduces the excess of calcium and mag- 
nesium, assists in balancing these mineral constituents, and 
thereby makes the casein more stable. 
Occasionally it happens, however, that the addition of sod1- 
um bicarbonate increases, instead of decreases, the viscosity and 
coagulability of the evaporated milk, and in such cases, the diffi- 
culty increases in direct proportion with the amount of bicarbon- 
ate added. In this case the viscosity and coagulability of the 
evaporated milk are undoubtedly due, not to an excess of calcium 
as is usually the case, but to a deficiency of calcium. Under such 
conditions a soluble calcium or magnesium salt should be added 
in the place of bicarbonate, in order to diminish the viscosity 
and to render the casein more stable. 
Acid Flux in the Cans Causes Lumps.—Similar as in the case 
of the sweetened condensed milk, the presence of acid flux in the 
cans of evaporated milk causes lumpiness. The acid that reaches 
the interior of the cans causes the milk coming in contact with 
the seams to curdie. Only acid-free flux should be used in the 
manufacture and sealing of the cans. 
Grainy Evaporated Milk. 
General Description.—This term is sometimes applied to 
lumpy milk, in which case it means the same. By grainy milk, 
however, is generally understood milk which contains a sediment 
of a white granular appearance, which is insoluble. 
Causes and Prevention..—This granular sediment is largely 
found in the hermetically sealed cans after the sterilizing process. 
It is due to excessively high sterilizing temperatures or too long 
1¥For detailed discussion of the effect of homogenizing on curdiness see 
Chapter IX on “Homogenizing” and Chapter XXIII on “Separated and Churned 
Evaporated Milk.” 
