Water vapor sorption in starch granules

A mathematical model proposed for diffusion in spherical particles can be solved on a digital computer. The model includes particle size distribution and variable diffusion coefficient of the form D = Doe^αC, where D is the diffusion coefficient, D₀ and α are constants, and C is the moisture content. Isothermal experimental measurements were made gravimetrically on a Cahn electrobalance by vacuum sorption techniques. The model adequately predicts the absorption characteristics of water vapor in starch granules. Although swelling is neglected in the model, it does contribute to sorption characteristics.