STUDIES ON METHOD FOR AQUEOUS EXTRACTION OF SOYBEAN OIL

Water extraction of soybean oil was studied to find the optimal conditions for recovery of oil pre-enriched protein and for aqueous extraction of soybean oil. Orthogonal tests were employed in the procedures of oil pre-enrichment and aqueous extraction. Soybeans were crushed to pass a 40 mesh sieve, soaked under the optimum conditions (solid/water=1/5(w/v), 40 ℃, pH 10, 3 h) and water-ground to 100 mesh, stirred in 65 ℃ water for 20 min, and centrifuged at 1400 g to separate oil pre-enriched protein. The protein yield was 17.8 g from 100 g soybeans, which contained 62.8% oil. The oil yield was 69.0%. Optimum conditions for the aqueous extraction procedure were: solid-to-water ratio 1∶2, pH 9.0, time 30 min, stirring in boiling water bath, stationary time 10 min, centrifuge at 3600 g for 10 min. Experimental values showed that the oil yield after aqueous extraction from oil pre-enriched protein reached 88.3%, so the total oil extraction rate was 60.8%.