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Transport processes and large deformation during baking of bread



A model of multiphase transport in a porous medium coupled with large deformation of the porous matrix is developed and applied to the process of bread baking. Transport-governing equations are based on energy conservation and mass conservation of water, water vapor, and CO2 produced during baking. Deformation is caused by the pressure gradient from internal evaporation and CO2 generation. Temperature, moisture, and pressure changes in turn are affected by deformation. Bread is assumed to be viscoelastic, mechanical properties of which are functions of temperature. Geometric nonlinear effects are considered in the mechanics problem. Results are compared with those from baking experiments and literature data. Vapor pressure inside the matrix is likely to be lower than the equilibrium vapor pressure. Convective heat transfer is small compared to heat conduction and evaporation–condensation of water vapor promotes heat transfer to the inside. Rate of CO2 generation, mechanical properties of dough, and gravity together determine the final shape of the bread. © 2005 American Institute of Chemical Engineers AIChE J, 2005