Biorecovery of antioxidants from apple pomace by supercritical fluid extraction

This work explored the potential of supercritical fluid extraction (SFE) to recover phenolic compounds and antioxidants from apple pomace. SFE was carried out at 20 and 30 MPa and temperature of 45 and 55 degrees C in absence and presence of ethanol (5%) as co-solvent. The results were then compared to those obtained by Soxhlet extraction with ethanol and boiling water maceration. All the extraction techniques were performed on fresh, oven and freeze dried samples. The extracts were characterized for their antioxidants capacity with different assays, such as the Folin-Ciocalteu, the 2,2-diphenyl-1-picryhydrazyl radical (DPPH) and a flow injection coulometry technique. The results showed that the extracts obtained from SFE, carried out on freeze dried apple pomace at 30 MPa and 45 degrees C for 2 h with ethanol (5%) as co-solvent, led to a higher antioxidant activity (5.63 +/- 0.10 mg TEA/g of extract) than conventional extraction technologies such as Soxhlet with ethanol (2.05 +/- 0.21 mg TEA/g of extract) and boiling water maceration (1.14 +/- 0.01 mg TEA/g of extract). The HPLC-DAD-MS analysis also confirmed the abundance of some phenolic compounds in SFE extract. Overall, the study presented here is one of the first investigations to assess the impact of supercritical carbon dioxide for the extraction of antioxidants from apple pomace. (C) 2018 Elsevier Ltd. All rights reserved.