Effect of non-covalent binding of phenolic derivatives with scallop (Patinopecten yessoensis) gonad protein isolates on protein structure and in vitro digestion characteristics

[Display omitted] •Four phenolics (EGCG, EGC, ECG, C) interact with scallop gonad protein (SGPIs) by non-covalent bonds.•Introduction of phenolics change the native conformation of the SGPIs, especially for EGCG.•SGPIs-binding affinity of phenolics increased as the number of –OH group increased: EGCG > ECG > EGC.•Hydrogen bond and van der Waals dominated the interaction process between SGPIs and EGCG.•EGCG-treated SGPIs digest exert higher ABTS+• scavenging activity than that of ECG and EGC. The present study was aimed to investigate the effects of non-covalent interactions between scallop gonad protein isolates (SGPIs) and different concentrations (20, 120 and 240 μmol/g, protein basis) of four phenolic compounds, such as (-)-epigallocatechin gallate (EGCG), epicatechin 3-gallate (ECG), epigallocatechin (EGC), and catechin (C), regarding the structural and functional properties of the complex. Total sulfhydryl and surface hydrophobicity in SGPIs decreased by nearly 72% and 65% with 240 μmol/g EGCG, similar but less appreciable changes were produced by EGC, ECG and C. Fluorescence quenching and thermodynamic parameters suggested that hydrogen bond and van der Waals dominated the interaction process between SGPIs and EGCG, and the interaction was further studied by molecular docking. Moreover, EGCG-treated SGPIs digests exerted higher ABTS+• scavenging activity than that of ECG and EGC-treated SGPIs. These findings are helpful to reveal the binding mechanism of phenolics and SGPIs, and provide a theoretical basis for the application of SGPIs-phenolic complexes as functional food additives.