Comparison between ethanol and hexane for oil extraction from Quercus suber L. fruits

Abstract

The aim of this study was to (i) evaluate the feasibility of replacing n-hexane with ethanol for the extraction of oil from Quercus suber fruits and (ii) optimize, at lab scale, sample preparation and extraction time for both solvents used (n-hexane vs. anhydrous ethanol). For both solvents, the effect of the conditioning process on extraction yield was evaluated. Therefore, a full factorial design was used as a function of four variables: dehulling (with vs. without husks), and thermal treatment of the crushed material (40°C vs. 75°C), at different times (5 min vs. 120 min) and pressures (10 kPa vs. 100 kPa). Higher oil yields were obtained with n-hexane when dehulled fruits were conditioned under atmospheric pressure. Better yields were obtained with n-hexane, when dehulled material was treated at 75°C for 90 min. Ethanol was not adequate for oil extraction from Quercus fruits, since other materials rather than oil were also extracted.