Prospective pathway for a green and enhanced friedelin production through supercritical fluid extraction of Quercus cerris cork

• SFE of Quercus cerris cork (300 bar and 40–80 °C), and Soxhlet extraction with dichloromethane.
• Betulin, squalene, and β-sitosterol identified for the first time in the extracts of Q. cerris cork.
• Friedelin concentrations up to 40.6 wt% by SFE, against 26.0 wt% using dichloromethane.
• SFE of Q. cerris cork is a prospective pathway for a green and enhanced friedelin production.

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.This study demonstrates that the SFE of Q. cerris cork arises as a prospective pathway for a green and enhanced friedelin production process under the biorefinery concept.

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