26 
BULLETIN 661, L T . S. DEPAKTMENT OF AGBICULTURE. 
lation. 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 3 T ield is there- 
FlG. 
— 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 solubilhV^, 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- 
