Influence of solvent polarity of ethonal/water binary solvent on the structural, emulsifying, interfacial rheology properties of gliadin nanoparticles

Gliadin nanoparticles (GNPs) is a promising material for stabilizing Pickering emulsions. The present work aimed to investigate the effect of solvent polarity of ethonal/water binary solvent on the structure and emulsifying property of GNPs and provide reference information for the potential application of GNPs in alcoholic food system. The structural, emulsifying and interfacial rheology properties of GNPs in aqueous phases with different polarity (EN(T):1.00–0.94) were evaluated. The solvent polarity was regulated by changing the ethanol concentration in aqueous phase. Results showed that the emulsifying activity of GNPs significantly improved as the EN(T) decreased from 1.00 to 0.96, and then decreased as the EN(T) further decreased from 0.96 to 0.94 for the rising particle size. Meanwhile, the decrease of solvent polarity improved the diffusion rate, viscoelastic modulus (E) and the interparticle interaction of GNPs. The possible mechanism was investigated by discussing the relationship among the structural, emulsifying and interfacial rheology properties of GNPs. It was found that the decrease of solvent polarity triggered the increase of hydrophobic groups distributed on the particle surface, and then resulted in the decrease of zeta potential and the increase of surface hydrophobicity of GNPs, which benefited the diffusion/adsorption of particles and the formation of viscoelastic protein layers for lower electrostatic repulsion, moderate surface wettability and stronger hydrophobic interaction. The results also suggested that GNPs might be a natural and economical material for low-degree alcohol emulsion food.