Stabilization of Pickering emulsion using tragacanth nanoparticles produced by a combination of ultrasonic and anti-solvent methods.

Background: Because of the high surface/volume ratio in nanometric size particles, they exhibit novel functional properties in many industries, such as emulsion stabilization. Tragacanth nanoparticles (TNPs) were prepared in this research, applying intense ultrasound energy followed by anti-solvent precipitation in ethanol.

Results: Investigation of wettability showed a contact angle of 88.9 ± 1.7° for TNPs, providing partial wetting of the nanoparticles at the oil-water interface. Pickering emulsions were prepared using TNPs at different oil contents. Also, emulsions containing tragacanth gum solution were prepared as control emulsions. Results showed that the viscosity of the emulsions prepared by the TNPs was significantly lower than those of the control emulsions. Microscopic images showed that the size of the emulsion droplets decreased by increasing the nanoparticle concentrations. Evaluation of the stability of the emulsions showed that changes in the average diameter of the emulsion droplets stabilized by nanoparticles were not significant after 1 month of storage at room temperature. In contrast, the size of the droplet of control emulsions increased over the 30 days of storage. Thermal and mechanical stresses confirmed the effect of the concentration of TNPs and the oil ratio on the stability of the emulsions.

Conclusion: The use of TNPs as a natural biopolymer is a promising approach in emulsion systems to prevent coalescence and increase the stability of the Pickering emulsions. © 2021 Society of Chemical Industry.