Solvent-free microwave extraction: an eco-friendly and rapid process for green isolation of essential oil from lemongrass

Abstract

The extraction of lemongrass essential oil (LGEO) using large quantities of solvents makes this extraction a hazardous and environmentally unfriendly procedure. Our aim was to find a suitable method for the improvement of its extraction and its quality. Solvent-Free Microwave Extraction (SFME) is a combination of dry distillation and microwave heating. SFME of LGEO was compared with conventional extraction hydrodistillation (HD). SFME is quicker than conventional HD. An extraction time of 15 min with SFME provided a yield of 0.6% comparable with that obtained after 120 min using HD. The composition of these oils revealed that the main components obtained with HD and SFME were both geranial (59.93% vs 44.59%, respectively). The quality of lemongrass is determined by its citral content, and a higher amount of citral was present in SFME oil (74%) in comparison with HD oil (60%). SFME is a green and a promising technology for the extraction of essential oils.

Keywords: Lemongrass; citral; essential oils; gas chromatography-mass spectrometry; green chemistry; microwave extraction.