Supercritical extraction from Citrus aurantium amara peels using CO2 with ethanol as co-solvent

• Supercritical (CO2 + ethanol) extraction of bioactives from Citrus aurantium peels.
• SFE extraction was optimized using response surface methodology, RSM.
• Best RSM work conditions at P = 170 bar; static time = 53 min; QCO2 = 2.9 kg h−1.
• Highest osthole yield (%) obtained in less than two hour of extraction period.

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 CO2 extraction 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 CO2 flow 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−1 of CO2 flow rate and 50 min of static time.

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