Molecular identification of salty and saltiness-enhancing peptides from Stropharia Rugosoannulata and their salinity perception with secondary structure and sodium chloride.

Given the significant health risks associated with high-salt foods, reducing salt intake in daily diets is very crucial. Saltiness enhancement peptides were identified and evaluated from Stropharia rugosoannulata protein hydrolysates using filtration methods, LC-MS/MS, and electronic tongue. Among those peptides, PQGDGW and WGFGDD with the lowest binding energies, recognized by two different receptors, transmembrane channel-like 4 (TMC4) and transient receptor potential vanilloid 1 (TRPV1), were synthesized. The sodium chloride perception concentration was 608.29 mmol/L for 0.1 % (w/v) PQGDGW in an aqueous solution, and its saltiness index (SI) value was 16.95 in 0.2 % (w/v) sodium chloride solution, indicating an excellent salty peptide with strong saltiness-enhancing ability, and its threshold concentration was above 0.02 % (w/v). WGFGDD was proved to be just a saltiness-enhancing peptide. Notably, as the salt concentration increased, the saltiness-enhancing effect of those two peptides diminished significantly, which might be due to the structural changes and salting-out effect.