The effect of screw speed (220-340 rpm) and feed rate (22.0-26.0 kg/h, db) on the firmness, expansion ratio, colour and sensory properties of a nutritionally balanced gluten-free extruded snack were investigated. Regression equations describing the effect of each variable on the responses were obtained. Results indicated that feed rate and screw speed both had an effect on the firmness of the product at 95% confidence interval (Cl). The interaction between the two factors was also found to be significant at 95% CL The effect of screw speed was significant whereas the quadratic effect of feed rate was found significant on the lateral expansion (95% CI). Lateral expansion increases as screw speed increases. The results indicated that changes in the extrusion variables did not affect the flavour and overall acceptability of the final product at 95% CI for the feed rate and screw speed ranges studied in this work. (c) 2005 Elsevier Ltd. All rights reserved.