INFLUENCE OF SALTS ON THE MICROSTRUCTURAL AND RHEOLOGICAL PROPERTIES OF HEAT-INDUCED PROTEIN NETWORKS FROM OVALBUMIN AND VICILIN

The influence of salts on heat-induced networks from ovalbumin and vicilin was investigated by using dynamic rheology and light microscopy. Optimum network characteristics were obtained with 300 mM NaCl or 5 mM CaCl2for ovalbumin and 200 mM NaCl or 20-50 mM CaCl2for vicilin. At higher NaCl concentrations the storage (G') and loss (G') moduli decreased while tan δ (G'/G') increased, indicating disruption of the network structure. Higher CaCl2concentrations resulted in increased vicilin network solubility (low G moduli and high tan δ values) and promoted ovalbumin aggregation (high G moduli and high tan δ). By use of several sodium salts in the lyotropic series, it was shown that for both ovalbumin and vicilin the promotion of intramolecular hydrophobic interactions in the protein during network formation reduced network strength. Only under highly stabilizing conditions (e.g., high concentrations of Na2SO4) was the influence on hydrophobic interactions sufficient to alter the structure of the network. © 1990, American Chemical Society. All rights reserved.