Preparation and characterization of pea protein isolate-egg white protein composite gels

The structure characteristics and gel properties of PPI/EWP mixtures with different ratios were investigated via surface hydrophobicity, solubility, rheological properties, sulfhydryl (SH) content, texture profile analysis, intermolecular forces, water-holding capacity (WHC) and microstructure. Results showed that the surface hydrophobicity of composite solutions decreased with the increase of EWP content while the solubility and the content of total SH increased. As the proportion of EWP increased, disulfide and hydrogen bonds, rather than hydrophobic interactions, played main roles in the formation of gels. The hardness of the gels and the storage modulus (G′) of the mixtures at the end of cooling both tended to rise and then descend with the increase of EWP content, and reached a maximum at the PPI/EWP ratio of 1:5. Additionally, the springiness and the WHC of the gels had a maximum at a PPI/EWP ratio of 5:1 and gradually decreased as EWP content continued to increase. The microstructural results revealed that the microstructure of the PPI-dominated composite gel was more dense and homogeneous. As the EWP content continued to increase, the composite gel was gradually transformed to have a network structure composed of protein aggregates and became rough and uneven.