ETHANOL-MODIFIED SUPERCRITICAL CO2 EXTRACTION OF CHESTNUT BURS ANTIOXIDANTS

Abstract Chestnut (Castanea sativa) burs is an underutilized solid by-product generated during the harvesting and processing of the edible fruit that could be used as a source of bioactive compounds in a context of circular economy concept. Supercritical CO2 extraction of chestnut burs was performed for the first time in this work. Supercritical extraction experiments were carried out in the ranges 10-30 MPa, 35-70 °C, 10-35 g CO2/min and different amounts of ethanol as polar modifier in order to evaluate the effect of the processing parameters in the extraction yield and antioxidant activity of the extracts. An overall extraction curve was measured at 25 MPa and 45 °C with 10 % ethanol as polar modifier reaching a global yield of 2.5 % after 3 h of extraction. Additionally, four different mass transfer models were used to describe the kinetics, showing a good fit with the experimental data.