EFFECT OF ETHANOL ON THE DRYING CHARACTERISTICS AND ON THE COUMARIN YIELD OF DRIED GUACO LEAVES (Mikania laevigata SCHULTZ BIP. EX BAKER)

Abstract Guaco is a common medicinal plant in Brazil used for the treatment of respiratory diseases. Coumarin serves as a chemical marker for quality control of products derived from guaco. In this study, the drying kinetics and coumarin yield of guaco leaves dried with and without treating the surface with ethanol were evaluated. The drying experiments were carried out in a forced convection tunnel at 50 and 60 ºC temperatures and air velocities of 0.42 and 0.84 m/s. The results show that the samples with ethanol experienced faster water evaporation during drying experiments, thereby reducing the drying time by up to 35%, and also had higher yields of coumarin. Storage experiments and color analysis were also performed. Treatment of dried guaco leaves with ethanol resulted in color degradation, but increased shelf life by 20%.