Nanoemulsion of D-limonene in water system prepared by ultrasonic emulsification.

D-Limonene is a component of essential oil extracted from citrus fruits. This component has shown chemopreventive and therapeutic activity against a wide variety of experimental tumors, but D-limonene is unstable and lose its lemon-like flavor under normal storage condition, and it is almost insoluble in water. Therefore, studying the formation of nanoemulsion in D-limonene in water system is probably a good method to prevent the oxidation degradation of D-limonene. For the purpose of our study, we used mixed surfactant to form D- limonene-in-water emulsion, and found the best formula for forming nanoemulsion droplets with specified hydrophilic-lipophilic balance (HLB) value and droplet size. The results demonstrated that nanoemulsion droplets formed at So ratio of 0.4 and applied power of 18 W for 120 s under mixed surfactant at HLB values 12 and had droplet size of 20-50 nm.