Fast Determination of Essential Oil Extracted from Fresh Orange Peel by Improved Solvent-free Microwave Extraction

Microwave absorption mediums (MAM) were first added into fresh sample system in order to improve conventional microwave heating mode using solvent or water to absorb microwave energy. Then, the improved solvent-free microwave extraction (ISFME) was first used in the extraction of essential oil from fresh plant material (orange peel). Three kinds of MAM, such as carbonyl iron powders (CIP), graphine powders (GP) and active carbon powders (ACP), were examined in ISFME. The results indicated that both CIP and GP were suitable for the ISFME, used in extracting essential oil from fresh plant material except ACP. By ISFME, the essential oil could be extracted completely from 100 g samples at the conditions of 85 W microwave irradiation power and 20 g MAM. The results obtained by the ISFME were then compared with those obtained by conventional solvent-free microwave-assisted extraction (CSFME), microwave-assisted hydrodistilation (MAHD) and conventional hydrodistillation (HD) in the constituents of essential oils, extraction time, electricity consumption and so on. It could be seen from the experimental results that there was no obvious difference in the quality of essential oils obtained by the four kinds of extraction methods. The ISFME took only 30 min and consumed electricity 0.43 kW.h/kg, both of which were much less than those of other methods. The effect of drying on the components of essential oil was also studied.