Kinetics of starch gelatinization during extrusion of tarhana, a traditional turkish wheat flour-yogurt mixture

Abstract

Tarhana, a traditional Turkish cereal food, was extruded at different extrusion conditions (product temperature: 60–120°C; screw speed: 100–300 rpm; feed rate: 10–20 kg/h). The mean residence time and corresponding degree of starch gelatinization data were used to estimate the order of reaction, gelatinization rate constants and activation energy for starch gelatinization. Results indicate that starch gelatinization exhibited an apparent first-order reaction kinetics with a reaction order of approximately 0.8. Activation energy for gelatinization was calculated as 3325 kJ/kg mol using the Arrhenius equation.