BARREL-VALVE ASSEMBLY AFFECTS TWIN-SCREW EXTRUSION-COOKING OF CORN MEAL

The effects of a barrel-valve assembly on extrusion system dynamics an d product properties with various screw speeds and specific feeding lo ads (SFL) were studied using an APV Baker twin-screw extruder. Turning the barrel-valve from the open to closed position resulted in a conve x response of die pressure due to the axial offset of paired orifice p lugs, with concomitant changes in system responses and extrudate prope rties. Variations in SFL by changing feed rate or screw speed caused m ore pronounced effects on product properties compared with barrel-valv e control.