Determination of the thermal diffusivity of bread as a function of porosity

Abstract

Experiments were carried out to determine the thermal diffusivity and the apparent density of bread crust and crumb as a function of porosity. The thermal diffusivity was determined by comparing the temperature profile obtained experimentally during heating of bread at 100 °C in an oven and the temperature profile calculated using a computer program to simulate heat transfer inside the product. Experimental measurements showed that the apparent density ϱ (kg/m 3) of the crumb and the crust follows a linear trend as a function of porosity ε(%): For the crumb: ϱ = 979 − 9.90 ε For the crust: ϱ = 895 − 9.0 ε The thermal diffusivity α ( m 2 s ) follows an exponential trend as a function of porosity: For the crumb: α = exp (0.01 ε − 15.25) For the crust: α = exp (0.0062 ε − 15.30)