Effect of ultrasound assisted emulsification in the production of Pickering emulsion formulated with chitosan self-assembled particles: Stability, macro, and micro rheological properties

Chitosan is not a good Pickering emulsion-stabilizer owing to its high hydrophilic properties at low pH. This study prepared chitosan self-assembled particles (pH chitosan = 6.6) stabilized Pickering emulsion by ultrasound assisted emulsification. The effects of ultrasound time on the microstructure, stability, macro and micro rheological properties of the Pickering emulsion were investigated, and the underlying mechanism of emulsion stabilization was also clarified. The chitosan particles were successfully adsorbed on the oil-water interface confirmed by the confocal laser scanning microscope (CLSM). After ultrasound treatment (20 kHz, 300 W, 1, 3, 5, 7, and 9 min), the droplet size and viscosity of the Pickering emulsion decreased. The macroscopic viscosity index (MVI), elasticity index (EI) of the Pickering emulsion decreased with the increase of ultrasound time, while the fluidity index (FI) was reversed. Ultrasound treatment improved the stability of Pickering emulsion observed by the turbiscan stability index (TSI) prior to 5 min. In conclusion, ultrasound assisted emulsification affected the stability of the Pickering emulsion mainly by affecting the particle size and viscosity of the emulsion. The chitosan self-assembled particles stabilized Pickering emulsion prepared by ultrasonic treatment (5 min) stabilized at room temperature at least for 60 days with no delamination.