Abstract: The objective of the present study was to optimize the process conditions for the modification of defatted corn gluten meal by two-screw extrusion by response surface methodology. The soluble protein content of extruded corn gluten meal was investigated with respect to water content before extrusion, extrusion temperature and screw rotation speed. The results indicated that the optimal twin-screw extrusion conditions were water content of 68%, extrusion temperature of 163 ℃ and rotation speed of 30 Hz (225 r/min). Under the optimal conditions, the soluble protein content of extruded corn gluten meal reached up to 3.43%. SDS-PAGE analysis demonstrated that the molecular weight distribution of soluble proteins in extruded corn gluten meal was in the range of 3500－14300 D, mainly consisting of polypeptides with a molecular weight between 3500 D and 6500 D. Modified corn gluten meal showed an obvious improvement in its physicochemical properties. Therefore, twin-screw extrusion is feasible to produce modified corn gluten meal.

Key words: defatted corn gluten meal, twin-screw extrusion, modification