Composition Comparison of Essential Oils Extracted by Classical Hydro distillation and Microwave-assisted Hydrodistillation from Pimenta dioica

The effects of microwave delivered power and radiation time in microwave-assisted hydrodistillation (MHD) on the yield and composition of the essential oil obtained from dry fruits of Pimenta dioica were studied. The optimum conditions for MHD were microwave delivered power 1000 W for microwave radiation time 3 min and then microwave delivered power 300 W for microwave radiation time 1 h at a 1:20 ratio of spice to water. In order to compare with classical hydrodistillation (HD), the HD extraction was also performed. The obtained oils were analyzed by GC and GC-MS. Twenty-four components were identified in the HD oil and twenty-two components in the MHD oil. Among the identified volatile compounds from P. dioica, the main components from both oils were found to be similar, but their contents were significantly different including methyleugenol (43.01% in the HD oil, 44.10% in the MHD oil), eugenol (28.84 %, 30.91 %), caryophyllene (6.64 %, 5.10 %) and alpha-pinene (6.34 %, 5.55 %). In addition two minor compounds, citronellal and palmitic acid are only present in the HD oil.