Supercritical CO2 extraction xanthophylls from Marigold extractum: Process optimization and extraction rate analysis

Xanthophyll have been extracted from Marigold using supercritical CO₂ at various extraction conditions due to its pharmacological actions. Xanthophyll content in the extract was also determined by high performance liquid chromatography (HPLC) method. Extraction was carried out at pressures of 220-300 bar, temperatures of 50-60 °C and CO₂ flow rates of 9-15 kg·h^-1. A 33 factorial design, in which pressure, temperature and CO₂ flow rate were used as design factors, coupled with statistical analysis of the results by using analysis of variance (ANOVA), was used to optimize operating condition of xanthophyll extraction by supercritical CO₂. Extraction rate constant was calculated from the dependence of extraction yield on extraction time at 30, 60, 90, 120 and 150 min. Based on the experimental results, the content of xanthophyll extracted from Marigold extractum was found to be 35.8%, and the maximum amount of xanthophyll extracted was obtained at 55 °C, 260 bar and 12 kg·h^-1. The optimization results demonstrated that temperature was the influential variable on the extraction content of xanthophyll, For xanthophyll extracted, all variables (temperature, pressure and CO₂ flow rate) were to be the influential variables, with the statistical significant effect p-value was smaller than 0.05. but there is no possible interaction among variables. The mean extraction rate constant, k, of xanthophyll increased with increasing pressure and temperature, and the k values were (1.0-8.1)×10^-3 min^-1.