Response Surface Analysis for Preparation of Modified Flours using Twin Screw Extrusion Cooking

Abstract

Abstract Rice flour, wheat flour and flour in combination (rice:wheat::50:50) were used to prepare modified flour using co-rotating twin screw extruder. The effects of barrel temperature, feed moisture and screw speed on product responses (specific mechanical energy[SME], expansion ratio and bulk density) were studied using response surface methodology. Extrusion variables were barrel temperature (125, 150 and 175°C), moisture content (14, 16 and 18%) and screw speed (300, 400 and 500 rpm). Expansion ratio was directly affected by barrel temperature, whereas increase in temperature decreased SME and bulk density. Feed moisture had positive effect on bulk density only, i.e. it increased with increase in moisture. Increase in screw speed was directly related to SME and expansion ratio. The higher R 2 values showed that the model developed for the response variables appeared adequate for predictive purposes.