Condensed Milk and Milk Powder, 193 



high temperatures, the particles of casein lose their property of 

 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. 



Both of these requirements of miscible milk powder, the 

 globular state of the fat globules and the natural emulsifying prop- 

 •erties of the casein, seem to be adequately met and complied with 

 in the product of the Merrell and Gere process. 



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, espe- 

 cially the oleic acid, the glyceride of which is an unsaturated fat, 

 oxidize readily, giving the product a rancid or tallowy flavor. 

 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 very much under the same con- 

 ditions as butter. In order to prevent whole milk powder 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 omniusefulness 

 and will remain a hinderance 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. 



