Optimization of extrusion process for development of antioxidant rich extrudates from finger-millet and horse-gram in rice matrix

Abstract

Innovative ready-to-eat extruded snack from optimized composite flour comprising of rice, finger millet and horse gram in a ratio of 40:50:10 was produced. Statistical optimization was carried out using central composite design of response surface methodology (RSM) and second order polynomial models were fitted to responses to understand the effect of different extrusion variables (feed moisture, temperature and screw speed) on product responses. All operational variables were found to have significant (P< 0.05) effect on expansion ratio, water absorption index, water solubility index, hardness, total phenolics and antioxidants. The multiple regression analysis demonstrated high significance of fitted models in predicting product response. Optimum processing condition generated from the models was: feed moisture: 11.36% wb, die head temperature: 130.58ºC and screw speed 329.03 rpm. The developed snacks had high sensory score with significantly higher total phenolic content (465.23 mg GAE/100g dw) and antioxidant activity (17.98 μmol TE/g dw) than market samples.