3.3. Supercritical Fluid Extraction (SFE)

For the extraction process, hop cones were ground to obtain an average grain size of 0.5 mm, and subjected to palletization. The produced pellets had dimensions 5 × (7–8) mm. The dynamic supercritical fluid extraction (SFE) process was performed on a ¼-technical (the extractor capacity of 40 dm³) scale research plant at the Łukasiewicz Research Network—New Chemical Syntheses Institute (Puławy, Poland) operating at temperatures up to 90 °C and pressures up to 1000 bar. Dried and pelleted hop cones (4 kg) were extracted with pure carbon dioxide according to 2-step procedure. As a 1st step, the extraction of hops was carried out at the temperature of 50 °C under the pressure of 250 bar with the consumption of CO₂ amounting to 50 kg CO₂/kg of the extraction input. As a result, the crude hop extract (E1) was obtained and the residues (R1), which were subjected to further extraction. As a second step, the post-extraction residues (R1) were re-extracted in order to obtain a xanthohumol rich extract (E2). The following parameters were used: pressure 800 bar, temperature 85 °C, and CO₂/EtOH (99:1; v/w) consumption of 105.1 kg/kg dry weight. The extract E2 was finally purified with the use of preparative chromatography. The extraction and purification of Marynka scCO₂ extract scheme is presented in Figure 2. Both steps were performed once.

The scheme of the separation and purification of bioactive compounds from Marynka hop cones scCO₂ extract. Abbreviations: E—extract, CPC—centrifugal partition chromatography, R—residue, SFE—Supercritical fluid extraction.