EFFECT OF PROCESSING CONDITIONS ON INTRINSIC-VISCOSITY OF EXTRUDED CORNSTARCH

Unmodified cornstarch from dent corn was used in this study to determi ne the effect of twin-screw extrusion conditions on the intrinsic visc osity of this polysaccharide and water. The study focused on the intri nsic viscosity of the cornstarch as a function of the key variables. P rimary variables examined were temperature (75, 100, and 125 degrees C ), starch concentration or consistency (35, 50, and 65%), and screw sp eed (100, 200, and 300 rpm) during the extrusion processing. The most favorable conditions examined were the extrusion of the cornstarch at 35% consistency, 100 degrees C, and 200 rpm. Two-thirds of the origina l intrinsic viscosity of the unmodified starch was retained upon extru sion at 35% consistency at all temperatures and the screw speeds (200 and 300 rpm) examined. Also, similar values were observed at 50% consi stency for 75 degrees C at 100 and 200 rpm and for 100 degrees C at al l three screw speeds. (C) 1996 John Wiley & Sons, Inc.