MANUFACTURE; OF MILK POWDER 247 



emulsifying and when the desiccated milk is redissolved, the casein 

 fails to be miscible, dropping to the bottom in the form of finely 

 divided, insoluble curd. In order to produce milk powder which 

 is miscible in water, the process and heat used must be such as to 

 permit the casein to pass into the finished product in its natural state. 



Rancid Milk Powder. From the biological point of view, milk 

 powder, properly made and with a minimum moisture content, 

 cannot decompose. Unfortunately, one of the constituents of dried 

 milk, the butter fat, is prone to undergo chemical changes upon 

 exposure to light, heat and air. The less stable fatty acids evidently 

 yield to chemical disintegration, giving the product a rancid and 

 tallowy flavor. Experimental data showing the exact action that is 

 responsible for this deterioration are not available. It is not improb- 

 able that both, hydrolysis and oxidation enter into this problem. Even 

 the most experienced manufacturers of milk powder, using the 

 most perfected processes now known, admit that milk powder made 

 from whole milk, or partly skimmed milk, will become rancid when 

 exposed to air, light and ordinary temperatures. 



Experience has amply demonstrated that whole milk powder 

 will deteriorate and become rancid and tallowy very much under 

 the same conditions as butter. In order to prevent whole milk pow- 

 der from becoming rancid, it must be stored in the cold. 



MARKETS 



Owing to its relatively poor keeping quality, the markets for 

 whole milk powder are limited. It is a most ideal substitute for 

 fresh milk or condensed milk, if used when fresh or whenever, in 

 its storage and transportation, it can be protected by cold. This 

 requirement, however, is a serious obstacle to its omni-usefulness 

 and will remain a hindrance to its introduction in the pantry of the 

 consumer, until the manufacturer succeeds in correcting this defect. 



Skim milk powder, on the other hand, is free from this draw- 

 back, and when properly made and kept dry, it keeps indefinitely. 

 It has become a most valuable dairy product and its uses are mani- 

 fold. It is used in the consumer's kitchen, in bakeries and confec- 

 tioners' establishments, in the manufacture of ice cream, fermented 

 milk beverages, and starters for cream ripening where milk and 



