Drying kinetics of Serjania marginata Casar leaves

This study aimed to evaluate the kinetics of drying of Serjania marginata leaves, as well as to adjust different mathematical models to the experimental values of the moisture ratio. The Serjania marginata Casar leaves were harvested with initial moisture content of 2.03 ± 0,10 decimal dry basis., and submitted to drying process under controlled conditions of temperature (40, 50, 60 and 70 ºC), until the moisture content of 0.08 ± 0,02. Ten mathematical models were fitted to the experimental data and utilized to predict the drying process of agricultural products. Based on the obtained results, the mathematical model of Midilli best represented the kinetics of drying leaves of Serjania marginata. The increase in temperature promotes: an increased rate of water removal in Serjania marginata leaves during drying; the increase of the effective diffusion coefficient, and this relationship can be described through the Arrhenius equation, which presents an activation energy for the liquid diffusion during drying of 81.39 kJ mol^-1 for Serjania marginata leaves; an increase in Gibbs free energy, while the enthalpy and entropy decrease.

Midilli model; diffusion coefficient; thermodynamic properties; moisture ratio