Unmodified cornstarch from dent corn was used in this study to determine the effect of twin-screw extrusion conditions on the intrinsic viscosity of this polysaccharide and water. The study focused on the intrinsic viscosity of the cornstarch as a function of the key variables. Primary variables examined were temperature (75, 100, and 125OC), starch concentration or consistency (35,50, and 65%), and screw speed (100,200, and 300 rpm) during the extrusion processing. The most favorable conditions examined were the extrusion of the cornstarch at 35% consistency, 100Β°C, and 200 rpm. Two-thirds of the original intrinsic viscosity of the unmodified starch was retained upon extrusion at 35% consistency at all temperatures and the screw speeds (200 and 300 rpm) examined. Also, similar values were observed at 50% consistency for 75Β°C at 100 and 200 rpm and for 100Β°C at all three screw speeds. 0 1996 John Wiley & Sons, Inc.' * Names are necessary to report factually on available data. However, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable.