Extraction of essential oil from rosemary leaves: optimization by response surface methodology and mathematical modeling

The extraction of essential oil from rosemary leaves is of interest for industrial applications as it is considered as a potential therapeutic agent to cure many diseases. Thus, the present study aims to optimize the extraction conditions. The effects of processing parameters of a steam distillation process on the extraction yield of rosemary essential oil are investigated using response surface methodology. A central composite design is applied to evaluate three independent variables such as extraction temperature (103-118 ºC), time (2-6 h) and feed mass (200-600 g) on the extraction of rosemary essential oil. The maximum yield under the optimum condition is 2.8 % (by wt.). Further, deviations between the experimental and predicted values are less, and they are statistically insignificant. Furthermore, the predicted data from the mathematical model that involves convection-diffusion processes show a good agreement with the experimental data of the extraction of rosemary essential oil by steam distillation. The major chemical constituents are determined using Gas Chromatography-Mass Spectroscopy. More importantly, rosemary essential oil shows antibacterial activity against two microbes. Therefore, the present study suggests that the optimum conditions for the extraction of rosemary essential oil and provide a good alternative to synthetic antioxidant.