Pickering emulsion gels stabilized by novel complex particles of high-pressure-induced WPI gel and chitosan: Fabrication, characterization and encapsulation

In this paper, WPI-chitosan complex particles (WCCPs) were prepared as a novel Pickering stabilizer based on high hydrostatic pressure (HHP). The mean particle size of WCCPs was larger than that of pure WPI gel particles (WGPs), and the zeta potential reversed from negative to positive, showing that chitosan molecules were adsorbed on the surface of WGPs. The three-phase contact angle (θo/w) of WGPs was about 120.7° while after addition of chitosan that of WCCPs can reach to 88.9°, indicating that WCCPs could be effective emulsifiers for Pickering emulsions. Rheological measurement demonstrated the formation of Pickering emulsion gels stabilized by WCCPs. The particle concentration of WCCPs affected the droplet size and creaming index of the Pickering emulsion gels significantly. Additionally, the emulsion gels strengthened as increasing the particle concentration of WCCPs. The interfacial structure of the Pickering emulsion gels was observed through the confocal laser scanning microscope images which showed that WCCPs coated densely on the surface of oil droplets performing like a compact barrier against coalescence. The effects of environmental stresses, including ionic strengths, pH and thermal treatment, were also evaluated. Lycopene was encapsulated in the WCCPs-stabilized Pickering emulsion gels and its stability during storage and in vitro release under simulated digestion were measured. Overall, these results showed that WCCPs were suitable for stabilizing Pickering emulsion gels and had the potential as a delivery system for bioactive compounds.