ROLE OF DISULFIDE BONDS IN DETERMINING THE RHEOLOGICAL AND MICROSTRUCTURAL PROPERTIES OF HEAT-INDUCED PROTEIN NETWORKS FROM OVALBUMIN AND VICILIN

The involvement of disulfide bonds in heat-induced networks from ovalbumin and vicilin was investigated by incorporating cysteine hydrochloride (CysHCl), mercaptoethanol (ME), and N-ethylmaleimide (NEM) during network formation. Network evaluation was based on rheological properties (small amplitude oscillatory testing) and microstructure (light microscopy). Low G' (storage) and G" (loss) moduli, elevated tan-delta (G"/G') values, and a reduction in protein cross-linking at ME and NEM concentrations of 25 and 50 mM supported disulfide bond involvement in ovalbumin networks. The impact of these reagents was seen during the final stage of cooling. Vicilin networks were unaffected by these reagents, indicating no disulfide bond involvement. While disulfide bonds may contribute to the elasticity and strength of a protein network, noncovalent forces are key to initial network formation.