Physicochemical properties and microstructure of soy protein hydrogels co-induced by Maillard type cross-linking and salts

The relationship between macroscopic (elasticity, swelling), microstructural and molecular properties was investigated in soy protein hydrogels formed by cross-linking to different degrees with a model Maillard type cross-linking agent (glutaraldehyde) in the absence or presence of 120 mM NaCl. Hydrogel macroscopic properties were not influenced by protein secondary structure. In contrast, rheological properties were strongly influenced by degree of cross-linking and microstructure. Cross-linking soy protein in the absence of salt led to the formation of a more porous network consisting of bigger flocs and/or bigger particles and to weaker gels. Gel swelling did not appear to depend on microstructural properties. The influence of cross-linking and salt on swelling would be connected to their respective impacts on elastic and ionic contributions to swelling.