Studies On The Protein Of Soy Bean : The Effects Of Neutral Salts Of Low Concentration On The Stability Of Soy Bean Protein Dispersed In Water

On adding neutral salt, such as ammonium sulfate, sodium sulfate and sodium chloride, to the soy bean protein sol, flocculation occurs in about 0.04 Mol. concentration of salt. It seems that this phenomenon is caused chiefly by globulin which is dispersed in relatively unstable state. Albumin does not flocculate at such a concentration, but yet it plays an important role in protecting globulin against the flocculation. The flocculation occurs in a different manner depending on varying proportion of albumin to gobulin. This will be explained by the protective action of albumin against the flocculution of globulin. In this connection egg-albumin has also the same effect upon the flocculation. The mechanism of this protective action may be postulated as follows: the adsorbed albumin plays the same role as bound-water, that is, albumin combines with globulin and protects it from the action of salt in such a way as to give the protein micelle greater hydration, higher potential and more stability against salt.