Thermophysical properties evolution of French partly baked bread during freezing

Few data are available on the thermophysical properties of the frozen partly baked breads, In this paper, thermophysical properties, including apparent and true densities, specific heat, enthalpy and effective thermal conductivity were determined separately for crumb and crust of partly baked bread. Total enthalpy of fusion, unfrozen water and solid specific heat were determined by differential scanning calorimetry. The apparent specific heats were estimated in base of the unfrozen water at -40 degreesC and initial freezing point. The effective thermal conductivity was measured with a line source probe in the range -35 to 25 degreesC. Four predictive models of the effective thermal conductivity of porous food were developed (parallel, series, Krischer and Maxwell models). The effective thermal conductivity predicted by Krischer model was in good agreement with the experimental data. (C) 2004 Elsevier Ltd. All rights reserved.