Response surface methodology for optimization of cinnamon essential oil nanoemulsion with improved stability and antifungal activity

Abstract The optimum formulation and ultrasonic condition for fabrication of cinnamon essential oil (CEO) nanoemulsion were determined using Response Surface Methodology (RSM). The CEO nanoemulsions were formed using ultrasonic bath (43 kHz at power output of 210 W) or ultrasonic probe (24 kHz at power of 400 W). The ultrasonic probe outperformed ultrasonic bath since it generated nanoemulsions with smaller droplet size, narrower size distribution as measured using polydispersity index (PDI), and higher viscosity. The influences of sonication time of 180.23 to 351.77 s, temperature of 4.82 to 45.18 °C, and Tween ® 80 concentration of 1 to 3 % w/w on the droplet size, PDI, and viscosity were investigated using RSM based on Box-Behnken design (BBD). The RSM revealed that the sonication time of 266 s, temperature of 4.82 °C, and Tween ® 80 of 3 % w/w produced the optimum CEO nanoemulsion with droplet size of 65.98 nm, PDI of 0.15, and viscosity of 1.67 mPa.s. Moreover, the optimum nanoemulsion had good stability in terms of droplet size and PDI when storing at 4, 30, and 45 °C for 90 days. The antifungal activity of the optimum CEO nanoemulsion was then investigated against Aspergillus niger , Rhizopus arrhizus, Penicillium sp., and Colletotrichum gloeosporioides in comparison to bulk CEO, and amphotericin B (as positive control). The results showed that the CEO nanoemulsion had better antifungal activity than bulk CEO.