Abstract: The effects of lactoferrin (LF)-epigallocatechin gallate (EGCG) covalent complex, prepared by alkaline treatment, and their physical mixture on the rheological properties, oxidative stability and in vitro digestion characteristics of fish oil emulsions were studied. As the molecular mass of LF increased after combining with EGCG, the emulsion viscosity was 2.74 and 1.42 times higher with the complex than with single LF or the physical mixture, respectively, and the complex remarkably enhanced the physical stability and maintained good fluidity of emulsions for 15 d at 55 ℃ consistently in the dark. The complex and the physical mixture were more effective at inhibiting fish oil oxidation than single LF; the thiobarbituric acid reactive substances (TBARS) values of lipids in fish oil emulsions stabilized by single LF, the physical mixture and the covalent complex were 2.25, 0.75 and 0.70 nmol/g, respectively on the 15th day of storage. During the in vitro digestion process, the covalent complex-stabilized fish oil emulsion showed better inhibition of aggregation and delayed release of fatty acids to some extent. This study provides a basis for the rational design of fish oil delivery systems.

Key words: protein-polyphenol covalent complex, fish oil, emulsion, digestion in vitro