Kiana Ghadiri - Active Pharmaceutical Research Center (APIRC), Pharmaceutical Science Branch, Islamic Azad University, Tehran, Iran.
Farhad Raofie - Department of Chemistry, Faculty of Science, Shahid Beheshti University, Tehran, Iran.
Mahnaz Qomi - Active Pharmaceutical Research Center (APIRC), Pharmaceutical Science Branch, Islamic Azad University, Tehran, Iran.
Ali Davoodi - Department of Pharmacognosy and Biotechnology, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran.

Background: Orange peel essential oils were obtained using supercritical fluid extraction. This method is an important high scaling extraction method used for the extraction of plant and animal extracts. Objectives: The aim of this study was the optimization of the extraction of the orange peel essential oil. Methods: The experimental parameters of Supercritical Fluid Extraction (SFE) such as temperature, pressure, and extraction time, and modifier volume were optimized using a central composite design after a ۲۴-۱ fractional factorial design. Orange peels were collected from ripe orange and were washed, air dried, and milled. Then, a Suprex MPS/۲۲۵ system in the SFE mode with a maximal operating pressure of ۳۹۵ bars was used for essential oil extraction. Moreover, GC-MS and GC-FID were used for the identification and determination of oil compounds, respectively. Results: Eight compounds have been identified based on their retention indices and mass spectra. According to the results, α-pinene, β-pinene, myrcene, d-limonene, terpinolene, C۸-aldehyde, citronellol, and linalool were identified in orange peel essential oil. The optimum SFE conditions were obtained at a pressure of ۳۴۷.۰۷ atm, temperature of ۵۵° C, extraction time of ۳۰.۱۶ min, and ethanol volume of ۱۴۷.۰۵ µL. Moreover, extraction yields based on SFE varied in the range of ۰.۰۴% to ۱.۱۸% (w/w).  Conclusion: The Results showed supercritical fluid technology as the best alternative technique for the extraction of pure and high-quality essential oil from orange peel. It is a green method and does not have any environmental impact.

Essential oils, Extraction, Supercritical fluid extraction, Volatile compounds