Mixed soy globulins and β-lactoglobulin systems behaviour in aqueous solutions and at the air–water interface

It has been studied in this work the effect of mixing soy globulins (β-conglycinin and glycinin) with β-lactoglobulin (βlg) both in the bulk phase and also in their interfacial (air–water interface) and foaming properties, at pH 3.0 and 7.0 and 20 °C. The analyzed properties of these systems were: particle size distribution (by dynamic light scattering (DLS)); dynamics of adsorption and surface dilatational modulus (by tensiometry); foam formation and stability (by conductimetric and optical measurements). Results revealed that mixture of 7S soy globulin and βlg at pH 7.0 presented a synergistic effect that is reflected in the formation of interfacial films of enhanced elasticity. The foaming properties were also improved (better foam capacity with foams made up by smaller air bubbles). There exists a close relation between these results and that obtained by DLS (existence of a complexation between β-conglycinin and βlg).