Abstract: In this study, heat-induced gels were made from mixtures of potato protein (PP) and egg white protein (EWP) at different ratios, and their texture properties, protein secondary structures, intermolecular forces, free sulfhydryl group contents and rheological properties were investigated. The results showed that with increasing level of PP, the water-holding capacity of mixed gels increased from (73.5 ± 0.71)% to (97.5 ± 0.71)% (P < 0.05) and the roughness gradually decreased. With increasing level of EWP, the hardness increased from (460.5 ± 4.4) g to (1 614.9 ± 126.4) g (P < 0.05). The two proteins complemented each other in water-holding capacity and hardness. When the ratio of PP to EWP approached 1, the secondary structure of mixed gels was transformed from β-sheet and α-helical to random coil, and the hydrogen bonds were gradually weakened. Hydrophobic interactions and free sulfhydryl contents increased with increasing level of EWP. The mixed gels with PP-EWP ratio of 1:0, 9:1 and 0:1 possessed higher elastic modulus. The gels strength was significantly positively correlated with hydrophobic interactions and free sulfhydryl group content (P < 0.01), and negatively correlated with water-holding capacity (P < 0.01), but had no significant correlation with storage modulus (P > 0.05).

Key words: potato protein; egg white protein; composite gel; texture properties; structure properties