Rasheed Ahmed Salim, Abu-Goukh ABA, Khalid HES and El-Hassan GM
The experiment was to evaluate the effect of three levels of redistillation of spearmint oil on spearmint quality such as physicochemical properties of the oil. Spearmint (Mentha spicata var. Viridis) plants were raised from underground runners obtained from fully mature plants. Eighty milligrams of spearmint oil were distilled in 200 ml of distilled water. Oil was extracted by water distillation according to the technique of British Pharmacopoeia. Physico-chemical properties including, relative density, optical rotation, refractive index, acid value and ester value were determined according to British Standards Institute. The process was repeated to give the first, second and third refined levels. Relative density, optical rotation and refractive index of spearmint oil significantly decreased with progress in the refining process. Acid values showed a decrease trend from 0.8475 in the crude oil to 0.5610, 0.4210 and 0.3740 in the first, second and third refined oils, respectively. Ester values significantly increased during the refining process from 11.22 in the crude oil to 12.01, 13.09 and 13.50 in the three levels of refining, respectively.