Abstract: The effects of varying screw speed，barrel temperature and moisture content on extrusion quality(expressed as degree of dextrinization)of materials comprised of buckwheat, melan-rice and coix were studied by using a co-rotating twin-screw extruder. The statistical model was established by using a rotate central composite design and response surface methodology.The operation parameters were conducted by triaxial contour map and isohypsic analysis. The experiment results showed great significance of exploitation of grist extrudate and the mechanism of the twin-screw extruder.

Key words: Twin-screw extruder Systemic model Response surface methodology