Most of the models available in the literature assume implicitly that the isotherm of the fermenting solids is equal to that of the substrate itself. Marques et al. demonstrated that the effect of the biomass on the isotherm needs also to be considered in mathematical models of SSF bioreactors [1].In order to evaluate the effects of the fermentation process on the drying characteristics of substrate is necessary to investigate the influence of temperature and volumetric air flow rate on the drying profiles of fermented and non-fermented material. Thin-layer drying equations are used to estimate the time course of drying process of several products and also to generalize drying curves. Several researchers have proposed numerous models for thin-layer drying of many agricultural products [5,6]. Currently, there are three types of thin-layer models used to describe the drying phenomenon. Namely, theoretical model, which considers only the internal resistance to moisture transfer between product and heating air, semi-theoretical and empirical which consider only the external resistance [7]. Theoretical model requires assumptions on the geometry of a typical food, its mass diffusivity and conduc-tivity; empirical model neglects the fundamentals of drying process and presents a direct relationship between average moisture and drying time by means of regression analysis [6].