Enhanced solvent-free microwave extraction of Foeniculum vulgare Mill. essential oil seeds using double walled reactor

Abstract

Enhanced solvent free microwave extraction (ESFME) using double walled microwave reactor was employed to improve and speed up the SFME process for the extraction of essential oils from Foeniculum vulgare Mill. seeds. At atmospheric pressure without any addition of solvent or water, experiments were performed in a double walled microwave reactor filled in their interlayer with distilled water as the heat-transfer fluid to increase the conduction of microwave heating during SFME. Results show that, essential oil isolated by ESFME was quantitatively (yield) and qualitatively (aromatic profile) almost similar to those obtained by SFME and hydrodistillation, but ESFME was found to be the best method in terms of extraction kinetics (30 min against 37 min for SFME and 180 min for hydrodistillation), energy saving, reduced cost and cleanliness process. Scanning electron micrographs provided more proofs to prove that the ESFME method is faster than the hydrodistillation method. Finally, ESFME appears as a fast, clean and efficient alternative for the extraction of essential oil from aromatic plants. Keywords: Double-walled reactor, Solvent-free microwave extraction, Essential oil, Foeniculum vulgare Mill. seeds