Solvent-free Microwave Extraction as the Useful Tool for Extraction of Edible Essential Oils

Abstract

Solvent-free microwave extraction (SFME) is proposed as a method for “green” extraction of edible essential oils extensively used in the fragrance, flavour, and pharmaceutical industries and also in aromatherapy. It is a combination of microwave heating and dry distillation, performed at atmospheric pressure without adding any solvent or water. Isolation and concentration of volatile compounds are performed by a single stage. Basil (Ocimum basilicum L.) was extracted with SFME at atmospheric pressure and 373 K for 30 min. The extracted compounds were removed from the aqueous extract by simple decantation, identified by gas chromatography–mass spectrometry (GC-MS). Hydrodistillation (HD) of basil was performed with 400 ml of water for 4.5 h for comparison of the results with those provided by the proposed method. SFME method offers important advantages over HD, viz. shorter extraction times (30 min vs. 4.5 h); better yields (0.13 % vs. 0.11 %); environmental impact (energy cost is appreciably higher for performing HD than that required for rapid SFME), cleaner features (as no residue generation and no water or solvent used); and provides a more valuable essential oil. SFME is a green technology and appears as a good alternative for the extraction of edible essential oils from aromatic plants used in aromatherapy and food industry.