Heat and mass transfer in par-baked bread during freezing

Abstract

To understand the phenomena governing the heat and mass transfers during the freezing of par-baked bread, simulation of freezing in an infinite two-layer cylinder was performed. A fixed grid finite difference method was used in the solution of simultaneous heat and moisture transfer (SHMT) equations according to Lees' three-level scheme. The model accommodates the effects of temperature dependent variables such as apparent specific heat, enthalpy, thermal conductivity, and water activity, and predicts the temperature profiles and weight losses. The model was verified by freezing of par-backed breads with cylindrical shape within an experimental freezer. The RMSE between experimental results and model predictions is 0.505 °C for surface temperature, and 1.8 °C for center temperature. The precision on the loss water is 10%. These results indicate that the method could be successfully applied to SHMT operations in foods freezing.