Sodium Bisulfite‐Induced Changes in the Physicochemical, Surface and Adhesive Properties of Soy β‐Conglycinin

Abstract

AbstractThe effects of sodium bisulfite on the electrophoresis profile; turbidity; and thermal, surface, and adhesive properties of soy β‐conglycinin protein were studied. Sodium bisulfite dissociated high‐molecular‐weight aggregates in the protein, and the aggregate percentage decreased with increasing sodium bisulfite concentration. Denaturation temperature of sodium‐bisulfite‐treated β‐conglycinin increased as sodium bisulfite increased. However, at high sodium bisulfite concentration (i.e. 36 g/L), denaturation enthalpy decreased significantly. Sodium bisulfite caused changes in the β‐conglycinin secondary structure and promoted ionization of lysine residues as indicated by FT‐IR results. A sudden drop in turbidity at pH 4.8 was observed at the same salt level. The contact angle of β‐conglycinin on cherry wood reached its minimum at 6 g/L sodium bisulfite and 24 g/L on glass. Water resistance of β‐conglycinin was improved but not significantly by 6 g/L sodium bisulfite at pH 9.5. An obvious increase in adhesion strength of the protein occurred at 3 and 6 g/L sodium bisulfite at pH 4.8. A high sodium bisulfite concentration at 36 g/L sharply reduced the adhesive performance of β‐conglycinin.