Abstract

Drying medicinal plant materials ensures the retention of their active ingredients. The aim of this study was to fit different mathematical models to experimental data from Aristolochia cymbifera leaves to determine and evaluate the effective diffusion coefficient and to obtain the drying process activation energy under varying air conditions. The experiment was conducted at the Federal Institute of Education, Science and Technology at the Goiás – Rio Verde Campus. Four drying replicates were performed in a fixed bed dryer with a controlled air speed of 1.0 m s^-1 and drying temperatures of 28.8, 36.4 and 44.8°C. Increasing the drying air temperature from 28.8 to 36.4 or 44.8°C reduced the A. cymbifera leaf drying time from 58.13 to 13.10 and 5.00 h, respectively. The diffusion approximation model described the drying phenomenon the best. The effective diffusion coefficient increased with increasing air temperature and was described by the Arrhenius equation with activation energy of 107.29 kJ mol^-1.

Key words: Medicinal plants, jarrinha, activation energy, effective diffusion.