The effect of extrusion conditions, including feed moisture (40–45%), screw speed (300–400 rpm) and barrel temperature (65–75°C) on the extrusion behaviour and extrudate properties of non-expanded rice snack was investigated and optimization of process variables was carried out using response surface and genetic algorithm. Polynomial equations were developed for the extrudate properties such as water solubility index (WSI), water absorption index (WAI), specific mechanical energy (SME), power consumption and throughput in terms of the independent variables. These equations were used as the objective function to find the optimum process conditions for extrudate. The developed equations of WAI, WSI and throughput were maximized whereas power consumption and SME were minimized for optimum process conditions. Common optimum process conditions required a low screw speed of 323rpm, high moisture content of 44.59% (db) and low barrel temperature 65.82°C. The experimental extrudate properties matched the values predicted for common optimum conditions more closely than those for individual optimum conditions and percentage errors were higher in case of individually optimized conditions.
