Suppression mechanism of L-lysine on the Epigallocatechin-3-gallate-induced loss of myofibrillar protein gelling potential

Abstract

As a natural antioxidant, Epigallocatechin-3-gallate (EGCG) needed to be added in high doses to maintain the quality of meat products. However, high doses of EGCG caused the excessive aggregation of myofibrillar protein (MP), which damaged the gel properties of MP gels. Therefore, the purpose of this study was to investigate the mitigation of EGCG-induced loss of MP gelling potential by L-Lysine (L-Lys). The results showed that the addition of 20 mM L-Lys induced excessive unfolding and loose aggregation of MP at 10 µmol/g EGCG, and hence, reducing the solubility (14.5%) and the tryptophan fluorescence, and forming a network structure with a large aperture. Therefore, the cooking loss was decreased from 29.20% to 15.13%, and the strength of MP gels was decreased from 0.35 N to 0.17 N. However, L-Lys hindered the hydrogen bonding interactions and hydrophobic interactions between MP and EGCG by competing the binding sites of MP at 50 µmol/g EGCG, which was supported by the Zeta potential, surface hydrophobicity, FTIR and molecular docking analysis. Thus L-Lys mitigated the protein aggregation caused by 50 µmol/g EGCG, improved the solubility (23.02%∼86.99%) and apparent viscosity, which were beneficial for the formation of a continuous network structure in MP gels. Therefore, the cooking loss of MP gels was decreased from 52.40% to 41.30%, and the gel strength was enhanced from 0.13 N to o.22 N with 20 mM L-Lys addition. The present study could provide a new strategy for increasing the amounts of EGCG in meat products without damaging the gel properties of meat products.

Keywords: Epigallocatechin-3-gallate; Gel properties; L-Lysine; Molecular docking; Myofibrillar protein; Suppression mechanism.