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 (40ºC vs. 75ºC), 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 75ºC for 90 min. Ethanol was not adequate for oil extraction from Quercus fruits, since other materials rather than oil were also extracted.