UNSWEETENED CONDENSED MILK DEFECTS 257 



sterilizer. The homogenizing pressure should be kept down to 

 one thousand to fifteen hundred pounds. 1 



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. The 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 sodi- 

 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 curdle. 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." 



