Composition comparison of essential oils extracted by hydrodistillation and microwave-assisted hydrodistillation from Piper nigrum L.

The essential oils of black pepper (piper nigrum l.) were isolated by classical hydrodistillation (chd) and microwave-assisted hydrodistillation (mhd) in yields of 1.24% and 1.45%,respectively. this study compared the chemical composition of the essential oils obtained by the two methods of hydrodistillation. we controlled also the effect of the volume of hydrodistillation solvent and the effect of microwave power on the oils chemical composition and yields. the optimum conditions for mhd were: microwave delivered power 700 w,microwave radiation time 30 min. and a 1:2 ratio of spice to water. the obtained oils were analyzed by gc and gc-ms. the main components from mhd oil were β-caryophyllene (8.25-52.68%),caryophyllene oxide (4.79-63.13%),sabinene (2.04-11.73%),α-copaene (5.95-9.28%) and cubenol (3.85-5.10 %). while the most abundant constituents identified in the chd oil were β-caryophyllene (47.14-50.88 %),α-copaene (7.79-8.02 %),sabinene (5.52-6.92 %) and cubenol (3.97-5.20 %). no significant effect of the volume of chd hydrodistillation solvent was found concerning the chemical composition oil. in contrary,the quantity of solvent and the microwave power showed several variations in the chemical composition of mhd oil.