Solvent-free microwave extraction of essential oil from dried patchouli (Pogostemon cablin Benth) leaves

Abstract

Solvent-free microwave extraction method was first employed to extract essential oil from dried patchouli (Pogostemon cablin Benth) leaves. The effects of solvent-free microwave extraction variables including microwave power, ratio between mass of raw material with volume of distiller (F/D), raw material size and extraction time on the yield of essential oil were investigated. Meanwhile, the effects of solvent-free microwave extraction method in the chemical components of essential oil were also evaluated. The optimized conditions was as follows: microwave power of 450W, ratio between mass of raw material with volume of distiller (F/D) of 0.06g/mL, raw material size of intact (4.66±1.41cm) and extraction time of 90min. Moreover, the extraction time was sufficient for solvent-free microwave extraction method to obtain higher yield than that using microwave hydrodistillation method for 3h, indicating a significant reduction of extraction time and an improvement of efficiency. The composition of the essential oil was then determined by GC–MS, and 16 components were identified. The composition of essential oil obtained using solvent-free microwave extraction method meets the quality standard ISO 3757: 2002 (E), and the major component is patchouli alcohol (53.68%). This study suggests that solvent-free microwave extraction method is a rapid and efficient alternative for the extraction of essential oil from dried patchouli (P. cablin Benth) leaves, with a great potential for industrial application.