Numerical Modeling of Heat and Mass Transfer during Contact Baking of Flat Bread

A multiphase model was developed to simulate heat and mass transfer during the baking process of flat bread (Sangak bread) by considering volume changes. In the proposed model, the equations of heat and mass transfer for liquid (water) and gas (vapor and CO₂) phases were developed based on Fourier's, Fick's and Darcy's laws, respectively. In addition, the effect of evaporation–condensation phenomenon was considered using the nonequilibrium relation of evaporation rate in the mass and heat transfer equations. The quantity of specific heat and density of each mesh was predicted using series and parallel models, and values of unknown parameters were estimated using the standard least square method. The nonlinear partial differential equations of the model were solved by using the finite element method by COMSOL Multiphysics software. The changes in bread thickness were determined by ImageJ software. The model validation was also accomplished by comparing the predicted temperature and moisture content with the experimental results. The high R² and the low root mean squared error between experimental and predicted data confirmed the validity of the developed mathematical model. PRACTICAL APPLICATIONS: The uniformity of the product quality and the energy loss during the baking process has always been considered as a great challenge in the baking industry. In recent years, there has been increasing demand for minimally processed and near‐fresh quality products. To produce the part‐baked Sangak bread, the dough fully processes and baking occurs to at level in which, the texture properly forms and low color changes occur. Nowadays, it is essential to find methods based on equations, mathematical modeling and engineering principles to improve process control. In order to develop these models, the profound understanding of the procedures during the baking, particularly, mass and energy transfer are essential. Since, there are few researches on evaporation‐condensation and volume change in contact baking; it is important to understand its mechanism for exploiting this phenomenon in the food industries.