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Supercritical fluid extraction (SFE) was applied for the first time to Quercus cerris cork, and compared with Soxhlet with dichloromethane (DCM). Novel triterpenes, viz. betulin and squalene, and β-sitosterol were identified for the first time in the lipophilic extracts.

The SFE at 300 bar and 40–80 °C provided extracts much richer in friedelin–the major compound from both SFE and DCM extracts – with concentrations up to 40.6 wt%, against 26.0 wt% for DCM. The SFE yields ranged between 0.97 and 1.81 wt% with pure CO₂, and attained 2.83 wt% when ethanol was introduced as cosolvent (10 wt%). In this case, however, the friedelin concentration dropped significantly due to the additional removal of non-target compounds. In general, the experimental data and their trends were in accordance with the theoretical predictions of kinetic and equilibrium properties estimated in this work for the friedelin/SC-CO₂ system …