Emulsifying Properties of Soy Protein Nanoparticles: Influence of the Protein Concentration and/or Emulsification Process

The interfacial and emulsifying properties of soy protein isolate nanoparticles formed by combined treatments of heating and electrostatic screening, as affected by variation of the protein concentration (c) and emulsification process, were investigated. These nanoparticles (with a z-average diameter of 103 nm at c = 0.1%, w/v) tended to aggregate at higher c values, and their internal structure was mainly maintained by hydrophobic interactions and disulfide bondings. In general, increasing c progressively favored diffusion and/or adsorption at the interface and formation of finer emulsions; increasing the energy input level of emulsification improved the emulsification efficiency and extent of droplet flocculation, as well as the emulsion coalescence and creaming stability. The rheological and creaming behavior of these emulsions was predominately determined by the amount of proteins adsorbed at the interface. The results confirmed that these nanoparticles can formulate Pickering emulsions with properties tailored by selecting c and the emulsification process.