Ferulic acid and EGCG alter the structural characteristics of ovalbumin and its application in mineral loading

Abstract

This study aims to fabricate mineral-loading nanocarriers using natural materials. The interaction patterns between ovalbumin (OVA) and four water-soluble polyphenols, namely ferulic acid (FA), (-)-Epigallocatechin 3-gallate (EGCG), gallic acid (GA) and epicatechin (EC), were investigated. Results showed that the optimised conditions for preparing stable OVA-polyphenol complexes are at the OVA-polyphenol ratio of 4:1 at pH 6, under which OVA-FA and OVA-EGCG showed the highest stability and mineral-loading capacity among four OVA-polyphenol complexes. The fluorescence results indicated that the addition of EGCG and FA induced a significant fluorescence quenching to OVA. The interaction between OVA and polyphenols involved hydrogen bonding, hydrophobic interaction and electrostatic interaction. Fourier transform infrared spectroscopy (FTIR) analysis suggested that both FA and EGCG enhanced the stability and orderliness of the structure of OVA. The transmission electron microscopy images also exhibited the spherical structure of OVA after the addition of FA and EGCG. Furthermore, scanning electron microscope-energy dispersive X-ray spectrum results suggested that OVA-FA and OVA-EGCG complexes were better mineral carriers than OVA-GA and OVA-EC. This study may serve as the theoretical support for the promising application of OVA in the fabrication of mineral-loading nanocarriers in functional food and pharmaceutic.