Preparation of bovine liver peptide-flavonoids binary complexes by free radical grafting: Rheological properties, functional effects and spectroscopic studies.

Free radical grafting is a green and fast method for modification of proteins and bioactive peptides. In this study, different flavonoids with flavonol, flavonoid glycoside and flavan-3-ol structures, such as quercetin (QC), rutin (RUT), and catechin (C), which are commonly used in food applications, were used as the research objects, and the binary systems of bioactive bovine liver peptides complexed with the flavonoids were prepared by free radical grafting method. The findings indicated that the affinity of catechin for bovine liver peptides markedly exceeded that of both quercetin and rutin. This observation was consistent with the extent of reduction in the content of free amino. The emulsion system formed using the binary complex was homogeneous and dense under optical microscopy, with reduced droplet diameters and significantly improved interfacial properties such as shear resistance. The combination of bovine liver peptides and flavonoids can be regarded as an effective means of modification.