Abstract
In this work liquid chromatography coupled with high-resolution mass spectrometry was applied for characterization of the antioxidants from apple pomace obtained by supercritical fluid extraction (SFE). SFE was carried out at 20 and 30 MPa and temperature of 45 and 55 °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), flow injection coulometry. A characterization of the extracts from freeze dried apple pomace treated at the optimized SFE conditions (30 MPa, 45 °C, 5% ethanol) and with Soxhlet has been performed by HPLC-DAD-MS. Individual phenolics were identified on the basis of their UV absorbance at 280 nm and comparison with external standards. 19 antioxidant compounds were assigned in the SFE and Soxhlet extracts. In SFE extract phlorizin, epicatechin, quercetin, and phloretin have enhanced signals. The intensity of the peaks detected in SFE extract was higher compared to the peaks of Soxhlet extract, indicating more antioxidant species available in SFE extract.