COMPOSITION AND PROPERTIES OF MILK POWDERS 315 



Bolting. The powdered milk resulting from the spray dry- 

 ing process of desiccation requires no grinding. It is very floury 

 in its physical make up, and after sifting it is ready to be packed. 



Packing of Milk Powder. The dried milk is put on the 

 market in packages of various types, such as fibre containers, tin 

 cans and barrels. The sizes vary from 8 ounce packages to 200 

 pound barrels. Of the small size packages the 10 pound can with 

 friction top predominates. The barrels vary some in net weight 

 with the process of manufacture used, the granular product of 

 the dough-drying and film-drying processes being heavier than the 

 flaky product of the spray-drying process. 



The bulk of milk powder reaches the market in barrels ; these 

 are paper lined, similar as sugar barrels. 



CHAPTER XXVII. 



COMPOSITION AND PROPERTIES OF 

 MILK POWDERS. 



Chemical Composition of Milk Powders. The chemical 

 composition of milk powders varies principally with the percent- 

 age composition of the original milk from which the powder is 

 made, and to some extent with the process of desiccating. 



The percentage composition of the fluid milk is controlled 

 primarily by locality and season of year, as determined by breed, 

 period of lactation and feed of the cows. For these reasons milk 

 powders made by the same process, but in different localities and 

 at different seasons of the year, often show very considerable 

 variations in their percentage composition. 



Effect of Atmospheric Conditions. The atmospheric con- 

 dition, especially with reference to humidity of the air, has a 

 further, frequently quite material effect on the chemical composi- 

 tion of the powder from the standpoint of dryness or moisture 

 content. Experience has amply demonstrated that when there is 

 a high degree of humidity in the atmosphere, the resulting milk 

 powder shows a higher per cent moisture than when made on a 

 clear, dry day. 



