Effect of cellulose nanocrystal supplementation on the stability of castor oil microemulsion

Abstract

Microemulsion (ME) is widely used in food, pharmaceuticals, and medical applications. In the formulation of MEs, a substantial amount of surfactant is needed to stabilize the lipo-hydrophilic interface, which may have adverse effects on biological cells. Cellulose and its derivatives have been extensively utilized as solid emulsifying agents, known as pickering agents, which are added to improve the stability of emulsions. In this study, ME made from a mixture of 5 wt% castor oil, 85 wt% surfactant/co-surfactant and 10 wt% water was modified by the addition of cellulose nanocrystal (CNC) in the aqueous fraction. The effect of CNC addition on the ME formation area, hydrodynamic diameter, and stability of resulting modified-MEs were investigated. While the addition of CNC did not contribute to the expansion of the ME formation area, the CNC supplementation has a significant influence on the hydrodynamic diameter and stability of ME. The results of this study demonstrate that the supplementation of CNC can reduce the usage of surfactant for ME formulation, with the use of CNC suspension containing 0.7 wt% CNC resulting in the most favorable hydrodynamic diameter and stability.