Extraction of custard apple ( Annona squamosal L.) peel with supercritical CO 2 and ethanol as co‐solvent

The aim of this work was to valorize the peel of custard apple fruit by supercritical CO2 extraction using ethanol as a co-solvent. Effect of various values of ethanol concentration (5%–15%), extraction time (30–60 min), temperature (40–70°C), and pressure (150–300 bar) on the polyphenols and antioxidant activities of the extracts were investigated. Response surface methodology based on a central composite rotatable design was used to optimize the total polyphenols content (TPC) and antioxidant capacity. The optimum condition was successfully selected at the ethanol concentration of 12%, the extraction time of 54 min, the temperature of 52°C, and the pressure of 261 bar. Under these conditions, the extract of custard apple peel achieved the TPC of 109.38 mg GAE/g, the antioxidant activity of 1197.79 μmol TE/g in the DPPH assay, and 1396.42 μmol TE/g in the ABTS assay. Novelty Impact Statement Custard apple (Annona squamosal L.) peel as a fruit by-product was valorized by using supercritical fluid extraction. Effects of ethanol co-solvent, temperature, pressure, and extraction time on the supercritical CO2 extraction of the peel were evaluated. Central composite rotatable design was used to optimize the total polyphenols content and antioxidant capacity of the extract.