Modelling of starch gelatinization kinetics of bread crumb during baking

Abstract

A mathematical model was set up to predict the extent of gelatinization of starch in bread crumb during baking. A bread dough was placed into a cylindrical steel mould and baked in a pilot forced-convection electric oven at 250 °C. A type J thermocouple was placed into the bread crumb (i.e. at a depth of 22 mm in axial position) in order to measure the temperature. Samples were extracted at different final baking temperatures (60, 65, 70, 75, 77, 80, 85, 90, 95, 98°C) and the determination of starch gelatinization kinetics was carried out on differential scanning calorimetric traces. It was shown that the extent of starch gelatinization follows first-order kinetics, where the rate constant varies with temperature according to the Arrhenius equation (Ko = 2.8 1018 s−1; Ea = 138 kJ/mol). Kinetics were validated under dynamic temperature conditions: the experimental results were compared with those obtained from a mathematical model for heat and mass transfer during baking connected to the kinetic model for gelatinization.