Preparation and characterization of lactoferrin-polyphenol conjugate with stabilizing effects on fish oil high internal phase Pickering emulsions

The combination of protein and polyphenol is an effective approach to improve the stability of protein emulsions. The lactoferrin (LF)-(−)-epigallocatechin-3-gallate (EGCG) covalent complex (LF-EGCG) was first prepared by alkali-induced reaction, then the structure and physicochemical properties between LF-EGCG and non-covalent complex (LF + EGCG) were compared, and finally the stability of complexes to fish oil high internal Pickering emulsions (HIPPEs) was tested. Results showed that LF-EGCG had stronger antioxidant activity, higher thermal stability, and better surface wettability than LF + EGCG. Meanwhile, the complexes showed no cytotoxicity within the tested concentration range (12.5–200 μg/mL). The HIPPEs stabilized with LF-EGCG possessed smaller droplet size, higher ζ-potential, and more uniform oil/water proton distribution. Covalent treatment also enhanced the storage, thermal, freeze-thaw and physical stability of LF HIPPEs. Furthermore, due to the higher antioxidant activity and denser microstructure, LF-EGCG HIPPE can more effectively inhibit the oxidation of fish oil.