Supercritical CO2 extraction of Helichrysum italicum: Influence of CO2 density and moisture content of plant material

Kinetics and selectivity of supercritical carbon dioxide (SC CO2) extraction of Helichrysum italicum flowers were analyzed at pressures in the range of 10–20 MPa and temperatures of 40 °C and 60 °C (density of SC CO2 from 290 to 841 kg/m3) and also at 10 MPa and 40 °C using flowers with different moisture contents (10.5% and 28.4%). Increased moisture content of H. italicum flowers resulted in enchased solubility of solute enabling decrease of SC CO2 consumption necessary for achieving desired extraction yield. The most abundant compounds in the supercritical extracts are sesquiterpenes and waxes while monoterpenes and sesquiterpenes are the main constituents of essential oil obtained by hydrodistillation. The optimal set of working parameters with respect to extraction yield, SC CO2 consumption and chemical composition of extract were defined related to moisture content of raw material and SC CO2 density.