Soy glycinin as food-grade Pickering stabilizers: Part. II. Improvement of emulsification and interfacial adsorption by electrostatic screening

Abstract

The development of food-grade particles as Pickering stabilizers has recently attracted increasing attention, and for protein-based particles, the role of surface charge in their emulsifying and interfacial properties is still little understood. The work reported that for the nanoparticles of heated (at 100 °C) soy glycinin (SG), the electrostatic screening by addition of increasing concentrations (0–500 mM) of NaCl was remarkably favorable for their emulsification performance and interfacial packing at oil-water interface. The influence of increasing ionic strength (μ) on the ability of these nanoparticles to form a gel-like emulsion was also investigated. In general, increasing the μ resulted in a progressive decrease in emulsion size and surface coverage at the interface, indicating improvement of the emulsification performance and interfacial packing. The improvement of emulsification and interfacial packing was largely associated with the enhanced diffusion and/or adsorption at the interface. If a high energy input of emulsification (microfluidization) was applied, a kind of gel-like Pickering emulsions stabilized by these nanoparticles would be produced. At protein concentrations of 0.5–2.0% (w/v), increasing the μ progressively increased the stiffness of the resultant gel-like emulsions. The results confirmed the importance of surface charge to the emulsification and interfacial behavior of protein-based (nano)particles, as well as formulation of Pickering emulsions stabilized by charged particles.