Novel kokumi peptides from yeast extract and their taste mechanism via an in silico study.

Yeast extract, a widely utilized natural substance in the food industry and biopharmaceutical field, holds significant potential for flavor enhancement. Kokumi peptides within yeast extracts were isolated through ultrafiltration and gel chromatography, followed by identification using liquid chromatography tandem mass spectrometry (LC-MS/MS). Two peptides, IQGFK and EDFFVR, were identified and synthesized using solid-phase methods based on molecular docking outcomes. Sensory evaluations and electronic tongue analyses conducted with chicken broth solutions revealed taste thresholds of 0.12 mmol L-1 for IQGFK and 0.16 mmol L-1 for EDFFVR, respectively, and both peptides exhibited kokumi properties. Additionally, through molecular dynamics simulations, the binding mechanisms between these peptides and the calcium-sensing receptor (CaSR) were explored. The findings indicated stable binding of both peptides to the receptor. IQGFK primarily interacted through electrostatic interactions, with key binding sites including Asp275, Asn102, Pro274, Trp70, Tyr218, and Ser147. EDFFVR mainly engaged via van der Waals energy and polar solvation free energy, with key binding sites being Asp275, Ile416, Pro274, Arg66, Ala298, and Tyr218. This suggests that both peptides can activate the CaSR, thereby inducing kokumi activity. This study provides a theoretical foundation and reference for the screening and identification of kokumi peptides, successfully uncovering two novel kokumi peptides derived from yeast extract.

Novel umami peptide from Hypsizygus marmoreus hydrolysate and molecular docking to the taste receptor T1R1/T1R3.

Hypsizygus marmoreus is an edible variety of mushroom with a distinct umami taste, which might be contributed by amino acids and umami peptides. Umami peptides have been widely studied, except for those from Hypsizygus marmoreus. Therefore, the main purpose of this study was to find new umami peptides in it. After the mushrooms were enzymatically hydrolyzed, they were separated and characterized by UF, GFC, RP-HPLC, UPLC-Q-TOF MS/MS and the umami peptide EGTAG was obtained. Sensory evaluation found that EGTAG had distinct umami taste with thresholds of 8.26 mmol/L and 10.04 mmol/L in water and chicken consommé, respectively. Molecular docking results showed that Glu120, Ser142, Asp162 and Gln361 of T1R1/T1R3 may play critical roles. Hydrogen and hydrophobic interactions were the main binding forces between T1R1/T1R3 and the umami peptide. We proposed umami peptide from Hypsizygus marmoreus may be used as savory enhancer in the salt-reducing foods in the future. HYPOTHESES: Edible fungi generally have umami taste and umami peptides from edible fungi had been reported in the literature. Hypsizygus marmoreus belongs to edible fungi and has umami characteristics, so it can be inferred that Hypsizygus marmoreus contains umami peptides.