ABSTRACT
The species Mentha piperita, popularly known as peppermint, is not only a medicinal plant but is also used in the pharmaceutical, food and cosmetic industries. Consequently, the drying process is necessary to increase shelf and product life, facilitating transport, handling and storage. For mint derivatives of quality, work into pre- and post-harvest is necessary. The aim of this study was to evaluate drying. To obtain the curves, temperatures in the range of 30 ºC to 70 ºC were used, with drying air velocity varying between 0.3 and 0.5 m.s-1. For drying the leaves, a laboratory-scale, fixed bed dryer was used, having a fan to move the air and a heating system. The results showed that the Midili model best fit the experimental data. The relationship of the diffusion coefficient to the drying temperature can be described by the Arrhenius equation, giving an activation energy of 68.42 KJ mol-1for a velocity of 0.3 m.s-1, and 78.27 KJ mol-1 for a velocity of 0.5 m.s-1.
Key words:
Medicinal plant; Drying kinetics; Mathematical modelling
