Abstract: Soybean extrusion before the aqueous enzymatic extraction of soybean oil can result in higher polypeptide yield. In this study, response surface methodology was employed to optimize process parameters for the aqueous enzymatic extraction of oil from extruded soybean in order to maximize soybean polypeptide yield. The optimal extraction conditions were alcalase amount of 1.6 %, temperature of 60 ℃, hydrolysis time of 3 h, material-to-liquid ratio of 1:5, and pH of 9.6. Under the optimal extraction conditions, the yield of soybean peptides was up to 41.36%, which revealed a significantly increase when compared with that obtained under the same extraction conditions without extrusion treatment.

Key words: extrusion, aqueous enzymatic extraction, soybean polypeptide