The Solubility of Casein in Salts of Certain Organic Acids, and Its Fractionation by Means of These Acids

The study of casein, the principal protein in milk, is being given increasing attention in research laboratories, not only because of the promising new ways in which it may be used in industry, but also because it affords a suitable material for the study of fundamental problems in protein chemistry. Strong acid and alkaline reagents have generally been used as solvents for casein, but they are not entirely satisfactory. Accordingly, the writers undertook experiments to determine the degree of solubility of casein in solutions of certain salts of organic acids. Nearly neutral aqueous solutions having a pH value of 4.6 (the isoelectric point of casein) were used in these experiments, since very little research work had been done with such solutions as compared to the work done with strong acids and bases.