Determination of extractability of pine bark using supercritical CO ₂ extraction and different solvents: Optimization and prediction

Bark from Pinus brutia was extracted with supercritical fluid extraction (SFE), using CO₂, at various extraction conditions both at laboratory and at pilot scale. Optimized parameters were 200 bar, 60 °C, and 3% ethanol at a solvent/feed ratio of 30. Additionally, the pine bark was sonicated (1 h at 50 °C) by different solvents (n-hexane, dichloromethane, ethyl acetate, and ethanol) to investigate the correlation between the different extraction setups and to obtain information on SFE up-scaling possibilities. Analyzed by HPLC, 7.2% of (-)-catechin was extractable at laboratory scale, and 58.4% (800 bar) and 47.8% (200 bar), both with modifiers, at pilot scale. By sonication with ethanol, 46.8% of (-)-catechin and almost 100% of (-)-epicatechin and (-)-catechin gallate were extracted. Ethyl acetate extract revealed high correlations with the laboratory scale SFE (r = 0.98) and also pilot scale SFE runs at 200 (r= 0.99) and 800 bar (r= 0.98) without modifiers.