Response surface optimization of hemp seed (Cannabis sativa L.) oil yield and oxidation stability by supercritical carbon dioxide extraction

Hemp seed oil is considered one of the best nutritional oil for health. The present work is focused on the optimization of the hemp seed oil extractive process at laboratory level using supercritical carbon dioxide (SC-CO2) as solvent. Response surface methodology (RSM) was used to optimize hemp seed oil extraction yield and oxidation stability. Independent variables were operating temperature (40, 50 and 60 °C), pressure (250, 300 and 350 bar) and particle diameter (0.59, 0.71 and 0.83 mm). A second-order polynomial equation was used to express both the oil yield and the oil oxidation stability as a function of independent variables. The responses and variables were fitted well to each other by multiple regressions. The maximum oil yield, 21.50% w/w, was obtained when SC-CO2 extraction was carried out at 40 °C, 300 bar and 0.71 mm of particle size. The maximum oil oxidation stability, 2.35 Eq α toc/ml oil, was obtained at 60 °C, 250 bar and 0.83 mm of particle size. A comparison between hemp seed oil composition extracted by SC-CO2 under the optimum operating conditions determined by RSM for oil yield and by organic solvent was reported.