Emulsifying properties of soy bean globulins and their variation with addition of some inorganic salts

Emulsifying properties of the total globulin fraction of soy bean proteins, of fractions rich in 11S and 7S globulins and of the 2S globulin fraction were estimated in terms of the lowest emulsifying protein concentration, the specific interfacial area, the adsorption of protein on the interface and the strength of interfacial adsorption layer. In salt-free solutions, 11S globulin had substantially poorer emulsifying properties than the other protein fractions; addition of small amounts of 0.1 mol/dm(3) NaCl made them comparable with other protein fractions. Addition of further NaCl, or KCl or Na(2)HPO(4), decreased the stabilizing efficiency of 11S globulin and other protein fractions; this can be explained by an increase in the conformational stability. The adsorption layers formed by 11S globulin were weaker than those formed by 7S globulin. A qualitative correlation was observed between the lowest emulsifying protein concentration, the specific interfacial area and the strength of the interfacial adsorption layers. These parameters did not correlate with adsorption.