Decoding of the Saltiness-Enhancing Peptides Derived from Walnut Meal Protein and Evaluation of Their Mechanism of Interaction with ENaC/TMC4 Receptors

Walnut meal protein hydrolysates showing a significant saltiness-enhancing effect were obtained through single-factor optimization and ultrafiltration. An integrated virtual screening strategy was employed to identify eight candidate saltiness-enhancing peptides, which were then evaluated for their saltiness-enhancing effect via sensory evaluations, electronic tongue, and salivary aldosterone. Incorporating the peptides AVEFDKWAGP, GPEHDW, and DDPRFT into NaCl solutions (3, 6, and 9 mg/mL) enhanced saltiness intensity by 19.79 ± 4.30 to 91.18 ± 10.00% and extended saltiness duration by 20.00 ± 0 to 66.67 ± 0%. The saltiness-enhancing peptide also increased salivary aldosterone concentrations by 18.30 ± 2.76 to 82.63 ± 7.19%, potentially contributing to a salt-reducing effect. Molecular docking revealed that hydrogen bonds played key roles in the binding interactions. Molecular dynamics simulations confirmed the stability and compactness of the peptide-receptor complexes. These results offer a practical strategy for formulating lower-sodium foods and expand the application prospects of walnut meal protein.