Emulsions stabilized by pea protein – Hydration and protein distribution

Abstract

This study investigates the structural properties of oil-in-water emulsions stabilized with pea protein using small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) techniques particularly as regards the hydration of the protein. The high protein content needed for stability (>5% w/v) is identified as being present mainly as a dispersed component in the aqueous phase contributing to network formation and increased viscosity. The hydration of the protein was distinguished through measurements with various D2O/H2O ratios. The dispersed protein is highly hydrated (75–80% water content). Additionally, pH-dependent scattering studies revealed significant structural rearrangements and aggregation of pea protein at acidic pH and around the isoelectric point, without greatly impacting emulsion stability. A range of pea protein concentrations were studied with increased amount of dispersed material in the aqueous phase at higher protein concentrations that results in smaller oil droplets and enhanced emulsion stability. Overall, these findings highlight the complex interplay between protein hydration, pH-induced changes and aggregation, and concentration on emulsion stability. This provides insights for optimizing protein-based emulsions in food applications, paving the way for novel protein-based emulsifiers.