Cereal Chem. 70:493-498   |  VIEW ARTICLE

Twin-Screw Extrusion of Rice Flour with Salt and Sugar.

F. Hsieh, K. M. Grenus, L. Hu, and H. E. Huff. Copyright 1993 by the American Association of Cereal Chemists, Inc. 

The effects of screw speed, salt (0-3%), and sugar (0-8%) contents on the extrusion of rice flour using a corotating, fully intermeshing twin-screw extruder were studied. Increasing the screw speed, salt, or sugar generally decreased the torque and die pressure. The screw speed was a more important determinant of the three processing variables (torque, specific mechanical energy, and die pressure) than was the salt or sugar content. The extrudate diameters (radial expansion) were affected only by the sugar content, not by the salt content or screw speed. The extrudate lengths (axial expansion) were higher at a screw speed of 300 rpm than at 200 rpm; they also increased with the salt and sugar. Significant increases in the specific volume were found with the addition of salt and sugar and an increase in screw speed. The breaking strength of extrudates was inversely related to the radial expansion. Raising the screw speed from 200 to 300 rpm resulted in whiter, less green extrudates.