Extraction of low-molar-mass phenolics and lipophilic compounds from Pinus pinaster wood with compressed CO₂

Near-supercritical and supercritical CO2 was used to extract low-molar-mass phenolics and lipophilic compounds from Pinus pinaster wood. Extraction of samples containing sapwood and knotwood was carried out at 10-25 MPa and 30-50 degrees C to assess the influence of the operational conditions on the yields of total extracts and phenolics, as well as on the radical scavenging capacity of extracts. The use of ethanol as a co-solvent increased both the extraction yields and the concentration of phenolics in extracts. Operating under selected conditions (25 MPa, 50 degrees C, 10% ethanol), the extraction yield accounted for 4.1 wt% of the oven-dry wood. The extracts contained up to 7.6g of phenolic compounds (measured as gallic acid equivalents) per 100 g extract, and showed one third of the radical scavenging capacity of Trolox. Native resin acids accounted for about 24g per 100 g extracts, whereas flavonoids, lignans, stilbenes and juvabiones were found at lower proportions.