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BULLETIN GG1, U. S. DEPARTMENT OF AGRICULTURE. 



lati'on. The acid and cooked-curd methods have the advantage of 

 requiring less vat capacity, and the casein can be made up in a 

 shorter time. 



YIELD OF SKIM-MILK CASEIN. 



The yield of skim-milk casein will vary from 2.9 to 3.5 per cent, 

 depending upon the composition of the skim milk, the method of 

 manufacture, and the extent of drying. Because of the better physi- 

 cal condition of the skim-milk curd there is not so much occasion 

 for loss of curd as in the case of buttermilk, and the yield is there- 



Fig. 9. — By means of a simple shaker screen the ground curd can be spread on the trays 

 in a short time and in a manner giving the most favorable drying conditions. 



fore higher. When the skim-milk casein is dried well, so that it 

 does not contain more than from 5 to 7 per cent of moisture, the yield, 

 with skim milk of average composition, ranges between 3 and 3.25 

 pounds to 100 pounds of skim milk. 



REQUIREMENTS FOR GOOD CASEIN. 



The practical value of casein depends upon its solubility, ad- 

 hesiveness, and general working properties. Casein of the desired 

 quality should dissolve within certain limits of alkalinity, giving a 

 clear, uniform solution, free from any scum or sediment, have a 

 fairly heavy body, and possess good adhesive qualities. The general 

 working properties of the dissolved casein, as determined by its vis- 



