Bioactive compounds extracted by liquid and supercritical carbon dioxide from citrus peels
Raffaele Romano, Lucia De Luca, Alessandra Aiello, Danilo De Rossi, Fabiana Pizzolongo, Paolo Masi
Abstract
Abstract This work investigated the extraction of bioactive compounds from citrus peels, an agri‐food waste. Carbon dioxide (CO 2 ), an eco‐friendly solvent, was used under liquid and supercritical conditions to perform the extractions from orange, tangerine and lemon peels. The possibility of using ethanol as a cosolvent at small percentages up to 20% was also studied. The extraction yield, total polyphenolic content, individual polyphenolic profile, antiradical activity and volatile organic compounds of the extracts were evaluated. The highest yields were obtained when 20% ethanol was used as a cosolvent in both liquid (at 20 MPa and 20 °C) and supercritical (at 30 MPa and 60 °C) CO 2 extraction. In addition, the extracts obtained with liquid CO 2 + 20% ethanol showed the highest content of naringin (35.26, 44.05 and 19.86 mg g ‐1 in orange, tangerine and lemon peel extracts, respectively) and terpenes, in particular limonene. This type of extract also showed the highest antiradical activity (31.78–59.51 µmolTE g ‐1 ) as measured by both ABTS·+ and DPPH·. These findings show that the extraction with a liquid CO 2 and ethanol mixture could be a valid alternative to traditional solvent extraction using 80% less organic solvent and producing extracts with high antiradical capacity and rich in volatile organic compounds.