Milk and Its Products. 287 



to considerable variation. The following analysis may be taken 

 as typical: 



Sweetened Unsweetened 



Per cent Per cent 



Water 25.7 71.7 



Fat 10.7 8.1 



Protein 8.5 8.7 



Milk sugar 11.9 9.9 



Cane sugar 41.9 .... 



Ash !.:', 1.6 



Milk powders are made by several processes. One of the 

 earliest was to evaporate the milk in a thin layer, on a heated 

 revolving drum. By this process the evaporation of water takes 

 place rapidly and the dried film of milk drops, or is scraped, 

 from the rolls, appearing as a' thin yellow scale. Another proc- 

 ess, of recent date, consists of atomizing the milk under pressure 

 into a moving volume of warm dry air. The moisture is in- 

 stantaneously absorbed and by the use of centrifugal force, the 

 vapor charged air is made to give up the minute particles of 

 suspended matter. The product is a fine flour, possessing, in 

 common, with some other brands prepared by other methods, 

 the properties of milk when again stirred up in water. There 

 are preparations on the market which do not have these prop- 

 erties, probably because they have been subjected to too high 

 heat in the drying process. 



Of the several milk powders examined by the authors, only 

 one contained any appreciable quantity of fat. It appears that 

 most, if not all of these powders are prepared from skimmed, or 

 partially skimmed milk. This is probably necessary, in order 

 that dessication may be more complete and the keeping qualities 

 of the product well insured. One product examined, and rep- 

 resented as a preparation from whole milk, contained but 9 per 

 cent of fat. A milk powder prepared from average whole milk 

 should contain at least 25 per cent of fat. 



Various other dry foods are prepared from the casein of milk, 



