Response Surface Methodology for Optimization of Supercritical Fluid Extraction of Orange Peel Essential Oil

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.

The aim of this study was the optimization of the extraction of the orange peel essential oil.

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 24-1 fractional factorial design. Orange peels were collected from ripe orange and were washed, air dried, and milled. Then, a Suprex MPS/225 system in the SFE mode with a maximal operating pressure of 395 bars was used for essential oil extraction. Moreover, GC-MS and GC-FID were used for the identification and determination of oil compounds, respectively.

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, C8-aldehyde, citronellol, and linalool were identified in orange peel essential oil. The optimum SFE conditions were obtained at a pressure of 347.07 atm, temperature of 55° C, extraction time of 30.16 min, and ethanol volume of 147.05 µL. Moreover, extraction yields based on SFE varied in the range of 0.04% to 1.18% (w/w). 

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.