MODELING OF BROWNING KINETICS OF BREAD CRUST DURING BAKING

A mathematical model was set rip to predict browning kinetics of bread crust during baking A bread dough was placed into a cylindrical steel mould and baked in a pilot forced-convection oven at 200 and 250 degr ees C. The sample surface temperature was measured using both a type J thermocouple and an infrared thermometer. Surface browning (Delta E) of bread crust during baking was measured by a tristimulus colorimeter . The kinetic model for bread crust browning was obtained by instant h eating of dried crumb on contact with a refractory plate at 140, 150, 165, 185, 210, 235 and 250 degrees C. At all temperatures Delta E tend ed asymptotically to Delta E(infinity) = 52, which corresponded to the burnt sample. The colour difference varies as a function of first-ord er kinetics. The rate constant k depends on temperature according to t he Arrhenius eqlration (k(0) = 42,000 s(-1) E(a) = 64,151 J/mol). Kine tics was validated under dynamic temperature conditions: the experimen tal results were compared with those obtained from a mathematical mode l for heat and mass transfer during baking connected to the kinetic mo del for browning. (C) 1995 Academic Press Limited