Fabrication and characterization of high internal phase Pickering emulsions based on pH-mediated soy protein-epigallocatechin-3-gallate hydrophobic and hydrophilic nano-stabilizer

Abstract

This study describes the feasibility of O/W High internal phase Pickering emulsions (HIPPEs) with an oil volume fraction of 0.82 stabilized by using SECNs at pH 3.0, 6.0 and 9.0. Soy protein isolate (SPI) was converted into the molten globule (MG) state at pH 3.0 and 9.0, modified by (−)-epigallocatechin-3-gallate (EGCG), and heated to obtain SPI-EGCG composite nanoparticles (SECNs). Results obtained demonstrated that with the introduction of EGCG in soy protein nanoparticles (SPNs) and increase in pH from 3.0 to 9.0, the particle distribution and tertiary structures of these nanoparticles were altered, along with decrease in surface hydrophobicity (H0), and enhancement of particle wettability and antioxidant activity. The structure of SPNs at different pH showed that there were two kinds of HIPPEs stabilizing mechanisms: nonshared multilayers (at pH 3.0 and 6.0) and mono-/shared layers (at pH 9.0). These findings provide insights into the design of protein-polyphenol nanoparticles stabilized HIPPEs suitable for the formulation of functional foods.