Abstract

Conventional volatile oil distillation consumes large amounts of time and energy. Microwave-assisted extraction (MAE) has proved an alternative method that reduces processing time and energy consumption. Conventional MAE systems, modified from an on-off power control microwave oven, lead to overheating of raw material, resulting in low-quality outputs. In this work, we design and develop a phase-power control microwave hydro-diffusion and gravity (PC-MHG) system in which continuous and adjustable power is archived. To verify the efficiency of the developed system, jasmine (Jasminum sambac) volatile oil was extracted in comparison with simultaneous steam distillation extraction (SSDE), in terms of yield, energy consumption, CO2 emission and the composition profiles. As a result, better percent yields, 0.07% and 0.03% at 500 and 100 W, respectively, were obtained, compared with the essential oil extracted by SSDE (0.004%). Some minor volatile compounds, extracted by solid-phase microextraction, were absent when volatile oil was extracted by both PME and SSDE. The typical compositions of volatile oil obtained by the two techniques, however, are quite similar. In conclusion, the developed microwave extraction system can provide substantial yield and quality of the volatile oil from jasmine, and can be developed for a large-scale industrial prototype.