Study on colour coordinates and maillard precursors of re-fabricated rice

Abstract

The effect of feed moisture, screw speed and barrel temperature on colour coordinates of re-fabricated rice grains were investigated in a co-rotating twin-screw extruder using response surface methodology. The rice flour obtained from broken rice (< 1/8th was used in the study. The screw speed was set at five levels between 49 and 150 rpm, barrel temperature between 59 and 110°C and feed moisture between 31 and 45%. All colour coordinates of re-fabricated grains evaluated (total colour difference) and hue angle were significantly affected by the three process variables. Barrel temperature was the most significant variable with quadratic effect on a*. Response surface regression models were established to correlate the colour coordinates of refabricated rice grains to the process variables. The optimized extrusion conditions for preparation of re-fabricated grains were 38%, moisture content, 130 rpm screw speed and 89°C barrel temperature. A significant change was observed in maillard precursors i.e. sucrose, glucose, fructose and maltose levels of re-fabricated rice obtained at optimum extrusion