Supercritical extraction from Citrus aurantium amara peels using CO2with ethanol as co-solvent

Citrus peels are important agro-food by-products of citrus processing industries that produce thousands of tons per year. This study aimed further exploitation of Citrus aurantium L. var amara peels for the recovery of bioactive components by using supercritical CO2extraction with ethanol as co-solvent. In order to optimize the extract yield a central composite design and the response surface methodology were used. The following independent variables were investigated: pressure (130–210) bar, static time (30–70) min and CO2flow rate (2.1–3.3) kg h−1. The statistical results show a significant quadratic effect of both pressure and flow rate of CO2. In addition, Sovová’s model was successfully applied to the experimental data. The peel extracts consisted of a collection of compounds including fatty acid esters (FAE), phenols, coumarin derivates, terpene derivatives, being the most concentrated osthole, isogeijerin, hexadecane and squalene. The most enriched peel extracts in osthole (∼47%) were obtained after 120 min of extraction time at 170 bar, 2.7 kg h−1of CO2flow rate and 50 min of static time.