Effect of the application of intermittent drying on Ilex paraguariensis quality and drying kinetics

The aim of this work was to study the effects of the application of tempering periods on the drying kinetics of yerba mate branches and on the resultant quality parameters of the finished product. Experiments were carried out in a convective pilot plant drier. Air temperature (60, 80 and 100 degrees C) and tempering time (0, 15 and 30 min) influenced the drying kinetics and the product quality (color parameters L and b, and the sugar and caffeine contents of an infusion prepared with the material). The influence of tempering time was higher at 60 of: than at the other temperatures. There were no differences between tempering times of 15 and 30 min. The Page model yielded a good fit to the experimental data, where the model parameter k varied with drying temperature. (C) 2009 Elsevier Ltd. All rights reserved.