title: Process optimization and stability of D-limonene-in-water nanoemulsions prepared by ultrasonic emulsification using response surface methodology.
abstract: D-limonene in water nanoemulsion was prepared by ultrasonic emulsification using mixed surfactants of sorbitane trioleate and polyoxyethylene (20) oleyl ether. Investigation using response surface methodology revealed that 10% d-limonene nanoemulsions formed at S0 ratio (D-limonene concentration to mixed surfactant concentration) 0.6-0.7 and applied power 18 W for 120 s had droplet size below 100 nm. The zeta potential of the nanoemulsion was approximately -20 mV at original pH 6.4, closed to zero around pH 4.0, and around -30 mV at pH 12.0. The main destabilization mechanism of the systems is Ostwald ripening. The ripening rate at 25 °C (0.39 m3 s(-1)×10(29)) was lower than that at 4 °C (1.44 m3 s(-1)×10(29)), which was in agreement with the Lifshitz-Slezov-Wagner (LSW) theory. Despite of Ostwald ripening, the droplet size of d-limonene nanoemulsion remained stable after 8 weeks of storage.
authors.affiliation: Institute of Food Science and Technology, National Taiwan University, 1 Sec. 4 Roosevelt Road, Taipei 10617, Taiwan, ROC.
authors.forename: Po-Hsien
authors.initials: PH
authors.lastname: Li
authors.forename: Been-Huang
authors.initials: BH
authors.lastname: Chiang
mesh_terms: D053138:Cyclohexenes / Q000737:chemistry*; D004655:Emulsions / Q000138:chemical synthesis / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D000077222:Limonene; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry; D013729:Terpenes / Q000737:chemistry*; D013997:Time Factors; D014465:Ultrasonics; D014867:Water / Q000737:chemistry*
chemical_list: D053138:Cyclohexenes; D004655:Emulsions; D013501:Surface-Active Agents; D013729:Terpenes; D014867:Water; D000077222:Limonene