A screening experiment with ten variables employing a Plackett-Burman experimental design was conducted on extrusion of rice flour. The variables include. hardware variables (mixing disk and reverse pitch screw elements). feed variables (moisture, sugar, salt and amylose contents, and particle size) and operating variables (barrel temperature, feed rate and screw speed). The response functions were extrusion characteristics (torque, specific mechanical energy and residence time), product attributes (water solubility index, water absorption index. and bulk density. peak viscosity, hot paste viscosity and cold paste viscosity). The response functions were highly affected by the hardware variables. A Plackett-Burman experimental design can serve as a useful tool for screening large numbers of variables and reducing the number of experiments. (C) 2002 Elsevier Science Ltd. All rights reserved.