Determination of quality and quantity of essential oils fromm lemon grass(cymbopogon citratus) of different maturity stages and from different environments

Abstract

This study evaluated the quality and quantity of essential oil of lemon grass of different maturity stages and from different environments. The essential oil of lemon grass was obtained by hydro-distillation and analyzed for its quality by thin layer Chromatography and UV visible spectrophotometry. There were significant effects of maturity stages on percentage yields of essential oil. The percentage yield of essential oil was higher at maturity stages of 5.5 months (0.41%) and 6.5 months (0.4%) month and lower at maturity stage of 7 months (0.32%). Small differences were recorded in percentage yields of essential from the different environments, (0.32% and 0.4%) when lemon grass was obtained from Busukuma at maturity stages of 7 months and 6.5 months respectively and (0.32% and 0.41%) from Salama Munyonyo at maturity stages of 7 months and 5.5 months respectively. There were significant changes in the chemical composition of essential oil obtained from lemon grass leaves of the different environments. Five components were detected in the essential oil of lemon grass, however only four components were present in the essential oil of lemon grass harvested from Busukuma at maturity stage of 7 months, component (b) linalool was absent compared to other essential oil samples that contained all the five components. The citral component (component c) was detected with Rf values from 0.62 to 0.66. The oil obtained also contained geraniol (component a), linalool (component b), citronellal (component d) and neryl acetate (component e) with retention factors (0.12-0.18), (0.24-0.30), (0.73-0.75) and (0.92 -0.95) respectively. The concentration of essential oil for the different maturity stages and environments (7 months (Busukuma), 6.5 months (Busukuma), 7 months (salama) and 5.5 months (salama)) were 13.675, 13.385, 13.263 and 14.629 mol L-1 respectively as calculated from beer lamberts law. At maturity stage of 5.5 months (salama munyonyo) the concentration of essential oil was highest while at maturity stage of 7 months (salama munyonyo) the concentration was lowest. It can be concluded that environment and maturity stage at harvest influenced essential oil content and composition. Therefore, lemon grass should be harvested at the appropriate level of maturity and environment in order to obtain high quality essential oil.