Effect of morphology on water sorption in cellular solid foods. Part I: Pore scale network model

A pore scale network model is developed to predict the dynamics of moisture diffusion into complex cellular solid foods like bread, crackers, and cereals. The morphological characteristics of the sample, including the characteristics of each cellular void and the open pore connections between them are determined from X-ray micro-tomography (XRT) data by means of 3D image analysis techniques. The 3D network allows to simulate the water vapor transport between the air cells through the open pores and the local sorption kinetics in the lamellae that separate them. In this way realistic moisture ingress profiles can be simulated in complex morphologies without need of unknown effective parameters. It is shown that the fine structure related transport characteristics embedded in the cell discretized network can be volume averaged to obtain a steady state relative vapor conductivity and a quasi-steady-state sorption time constant. These essential morphology related parameters can be used for an equivalent continuous two-equation description for a homogeneous product.