Soy flour was added at levels of 5%, 10%, and 15% of Hom Nil rice flour for extrusion at 190°C barrel temperature and 350 rpm screw speed. The extruded snack qualities decreased inversely with soy flour. However, product qualities were considered to be optimised when soy flour at 5% was added. The effect of feed moisture content (15, 17, 19 g (100 g) )1 wb), barrel temperature (150, 170, 190°C) and screw speed (350, 400, 450 rpm) on physicochemical properties of the snack were then investigated. The physicochemical properties of the product including expansion ratio, density, water absorption index (WAI), water solubility index (WSI) and hardness were evaluated. All properties were related, as linear equations, in terms of feed moisture content, barrel temperature, screw speed with relative correlation (R 2 ) at 0.83-0.94. The snack properties along with consumer acceptance were all highest when the extruded condition were 15 g (100 g) )1 wb feed moisture content, 170°C of barrel temperature and 450 rpm of screw speed.

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