Effect of NaCl on the Rheological, Structural, and Gelling Properties of Walnut Protein Isolate--Carrageenan Composite Gels

In this study, we discovered that a certain concentration of Na+ (15 mM) significantly improved the bond strength (12.94 +/- 0.93 MPa), thermal stability (72.68 degrees C), rheological properties, and textural attributes of walnut protein isolate (WNPI)-kappa-carrageenan (KC) composite gel. Electrostatic force, hydrophobic interaction, hydrogen bond, and disulfide bond were also significantly strengthened; the alpha-helix decreased, and the beta-sheet increased in the secondary structure, indicating that the protein molecules in the gel system aggregated in an orderly manner, which led to a much denser and more uniform gel network as well as improved water-holding capacity. In this experimental research, we developed a new type of walnut protein gel that could provide technical support for the high-value utilization and quality control of walnut protein.