Application of response surface methodology for the optimization of supercritical fluid extraction of essential oil from pomegranate (Punica granatum L.) peel.

Essential oils and volatile components of pomegranate (Punica granatum L.) peel of the Malas variety from Meybod, Iran, were extracted using supercritical fluid extraction (SFE) and hydro-distillation methods. The experimental parameters of SFE that is pressure, temperature, extraction time, and modifier (methanol) volume were optimized using a central composite design after a (24-1) fractional factorial design. Detailed chemical composition of the essential oils and volatile components obtained by hydro-distillation and optimum condition of the supercritical CO2 extraction were analyzed by GC-MS, and seventy-three and forty-six compounds were identified according to their retention indices and mass spectra, respectively. The optimum SFE conditions were 350 atm pressure, 55 °C temperature, 30 min extraction time, and 150 µL methanol. Results showed that oleic acid, palmitic acid and (-)-Borneol were major compounds in both extracts. The optimum extraction yield was 1.18 % (w/w) for SFE and 0.21 % (v/w) for hydro-distillation.