Utilization of β-lactoglobulin- (−)-Epigallocatechin- 3-gallate(EGCG) composite colloidal nanoparticles as stabilizers for lutein pickering emulsion

Controlling and manipulating thickness, packing, charge and chemical composition of the interfacial layer is highly relevant to the fabrication of stable emulsion delivery systems. In this work, composite nanoparticles with antioxidant capacity were prepared using β-lactoglobulin nanoparticles (β-lgNPs) and (−)-Epigallocatechin-3-gallate (EGCG) and applied as Pickering emulsifiers to stabilize a model lutein emulsion. The primary interactions between β-lgNPs and EGCG were found to be hydrogen bonding and hydrophobic effects through Fourier transform infrared spectra. β-lactoglobulin-EGCG composite nanoparticles (β-lgENPs) exhibited much stronger antioxidant activity than β-lgNPs, especially for β-lg-EGCG at a molar ratio of 15:1. Adsorbed protein fraction (Fads), saturation surface load (Гsat), adsorbed layer thickness as well as dynamic interfacial tension were determined to compare the interfacial adsorption properties of native β-lg, β-lg-EGCG complexes, β-lgNPs and β-lgENPs. The binding of EGCG had almost no influence on the physical stability of either native β-lg or β-lgNPs stabilized emulsions. The least degradation of lutein occurred in the emulsion stabilized by β-lgENPs, in which 87.2% of lutein was still retained in emulsion after 30 days of storage, confirming the enhanced protection by the formation of β-lgENPs. Potential mechanisms were proposed to explain the difference between β-lg-EGCG complexes and β-lgENPs in stabilizing lutein emulsions.