CHAPTER X 

 MILK BY-PRODUCTS 



98. Uses of By-products. — In the manufacture of 

 butter and cheese the by-products are skim milk, 

 buttermilk, and whey. These products are used 

 mainly for animal-feeding purposes and have a high 

 food value. Also from the by-products a number 

 of commercial articles are prepared. From whey, 

 milk sugar is manufactured, and from skim milk, 

 proteids are precipitated and prepared for commer- 

 cial uses. 



99. Skim Milk — Composition, Value, and Use. — I n 

 the manufacture of butter, about 80 per cent of skim 

 milk is obtained. The chief ingredients of skim 

 milk are casein, albumin, ash, and milk sugar. Be- 

 cause of the removal of the fats in skimming, the 

 solids not fat are usually present in the skim milk 

 in slightly larger proportions than in the ^^•hole 

 milk. Skim milk is characterized as a food of high 

 proteid content and it is valuable in combination 

 with other foods that are lacking in protein, par- 

 ticularly for the feeding of young and growing ani- 

 mals. iVverage skim milk contains about 9.75 per 

 cent of solid matter, of which 3.7 pounds are casein 

 and albumin, and .3.15 pounds are sugar, the remain- 



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