Yeast extract-mediated bidirectional regulation of off-odor binding to myofibrillar protein: Mechanisms for off-odor control in surimi products

Abstract

Controlling off-odor is crucial for improving the sensory quality and consumer acceptance of surimi products. In this study, yeast extract (YE) was innovatively applied to regulate/control off-odor release in surimi products. The changes in structure and off-odor binding capacity of myofibrillar protein (MP) with 0%–2 % YE were monitored during two-stage heating. Notably, MP structural changes in MP induced by YE affected its binding capacity to off-odors, showing a bidirectional regulating effect, i.e., an enhanced capacity at low addition (0.5%), whereas a weakened capacity at high addition (2%). The low YE addition promoted protein unfolding to increase binding sites number and reinforce binding forces (hydrophobic interactions, electrostatic interactions and hydrogen bonds) between MP and off-odors, thus inhibiting release of off-odors. Whereas, excessive YE causes its own aroma compounds to compete with off-odor compounds for binding sites on MP, thus contributing to release off-odors during processing procedure. Molecular dynamics simulations illustrated that L-Arg in YE engaged acidic amino acid residues on MHC in MP through electrostatic interactions, while L-Glu abundant in YE interacted with Arg, Tyr, and Ala residues on MHC via electrostatic, ion-dipole, and hydrogen bonding, thereby inducing structure-function shifts on MP. Molecular docking further revealed that MHC structure change induced by L-Arg and L-Glu in YE affected its binding to off-odor compounds. This study elucidated the bidirectional modulation effects and mechanism of YE on modifying off-odors binding capacity and revealed key role of charged amino acids in YE, offering a clean-label tool for off-odor control in surimi processing.