Comparative analysis of the oil and supercritical CO2extract ofCymbopogon citratusStapf.

Abstract

Dried and ground leaves of lemon grass (Cymbopogon citratus Stapf.) were used as a matrix for supercritical extraction of essential oil with CO₂. The objective of this study was to analyze the influence of pressure on the supercritical extraction. A series of experiments were carried out, for 360 min, at 50°C and at different pressures: 90, 100, 110 and 120 bar. Extraction conditions were chosen to maximize citral content in the extract oil. The collected extracts were analysed by GC–MS and their composition was compared with that of the essential oil isolated by hydrodistillation and by steam distillation. At higher solvent density the extract aspect changes passing from a characteristic yellow essential oil to yellowish semi-solid mass because of the extraction of high molecular mass compounds. The optimum conditions for citral extraction were 90 bar and 50°C, at these conditions citral represent more than 68% of the essential oil and the extraction yield was 0.65% while the yield obtained from hydrodistillation was 0.43% with a content of citral of 73%.