Heat and moisture transfer in baking of potato slabs

Heat and mass transfer in a slab of potato potato during baking were explained using a multiphase porous media model that includes internal evaporation and capillary, diffusive, and pressure driven transport of water and vapor, The model also includes the effect of the formation of a surface "skin" during baking. Model predictions were validated using experimental data. Most of the temperature drop in the material occurs in a relatively thin and dry surface region, while much of the interior stays at somewhat uniform temperature. Moisture content inside the material stays uniform except near the surface region where it drops to very low values. Evaporation occurs over a significant region, as opposed to at a sharp front. Baking time reduces significantly with thickness, however at a slower rate compared to conduction-only heating (no moisture transport). In addition, the surface temperature also reaches a higher value for a thinner material, which may help develop the often desired crusty surface. The skin layer can reduce the vapor loss from the surface, and consequently, increase the surface temperature and center temperature so that the baking time can be reduced. This process is sensitive to the permeability of the skin layer. Decreasing initial moisture content in the food and increasing air temperature and the heat transfer coefficient reduces baking time. The comprehensive nature of the model makes it relatively easy to extend it to hybrid processes such as microwave baking.