Drying kinetics analysis of sage leaves

The aim of this work was to study the drying of sage at different air temperatures and to fit the experimental data with different mathematical models. The experiments were carried out using 6 tray dryers, for the temperatures of 40, 50, 60, 70, 80 and 90 degrees C. A randomized experimental design, with three replications, using 800 g of fresh leaves in each tray, was used. For the fitting of mathematical models to the experimental data the non-linear regression by the Quasi-Newton method was used. The values of the parameters of the models were estimated in terms of drying air temperature using the software Statistica 6.0 (R). The results showed that small increments in drying air temperature of drying results in a significant reduction in the drying time; the model of Henderson and Pabis (1961) modified model and the Midilli et al. model (2002) were adequate to describe the drying of sage in the temperature range of 40 to 90 degrees C; and the model of approximation of diffusion and the two terms model were adequate to describe the kinetics of drying in the range of temperature from 60 to 90 degrees C.