Abstract

• Essential oils from plant species have played an important role in the fields of food industry, drugs, mosquito repellent, perfumes and other chemicals of important economic values. In this research work, essential oils from spearmint plants (Mentha spicata L.) were extracted using a method of microwave-assisted hydrodistillation (MHD) and conventional methods such as steam distillation (SD) and hydrodistillation (HD). Microwave-assisted hydrodistillation is an advanced and innovative hydrodistillation technique, in which a microwave oven (250v-50Hz power source; 2450MHz, output power 800Watt) was used as the heating source. The effects of extraction time (15 min, 30 min, 45 min, 60 min and 75 min) for microwave-assisted hydrodistillation and (30 min, 60 min, 90 min, 120 min, 150 min and 180 min) for steam distillation and hydrodistillation on the yield of essential oils were investigated. It was found that the highest yield percent of spearmint essential oils obtained by steam distillation and hydrodistillation were 0.07 % w/w and 0.05 % w/w while that of 0.09 % w/w for microwave-assisted hydrodistillation. The physico-chemical properties of essential oils such as color, specific gravity, refractive index, acid value and solubility in ethanol were analyzed. The extracted essential oils were also identified by Gas Chromatography-Mass Spectrometry (GC-MS). It was observed that carvone in spearmint essential oils was the major key component, with the highest concentration in 58.63 % by steam distillation, 56.91 % by hydrodistillation and 59.49 % by microwave-assisted hydrodistillation.