Impact of polar bio-solvent, particle size and soaking time on microwave-assisted extraction of edible oil from black soybean

Abstract

In this study, an efficient and green technology i.e. microwave-assisted extraction (MAE) was applied to extract the crude oil from black soybean (Glycine max var). During experiment, effect of three independent variables, solvent type (iso-propanol, ethanol, iso-propanol + water and ethanol + water), particle size (<1, 2 and 4 mm) and soaking time (0, 20 and 40 min) on the extraction yield was studied. Experiments were designed using full factorial design. The optimal MAE processing parameters were iso-propanol + water solvent, <1 mm particle size and 20 min soaking time, with an extraction yield of 93.56 %. The optimized MAE method was compared with conventional mechanical extraction and n-hexane solvent extraction. There was non-significant difference between oil yields and significant difference between extraction times in microwave-assisted and conventional solvent extraction. Exactly opposite effect observed during comparison of MAE with mechanical extraction. MAE gives 37.06 and 1.56 % higher crude oil yield than conventional mechanical extraction and n-hexane based solvent extraction, respectively.