KINETICS OF AQUEOUS EXTRACTION OF MATE (ILEX PARAGUARIENSIS) LEAVES

Experiments were carried out to investigate the kinetics of infusion of mate leaves. A cylindrical batch extractor made of glass and equipped with a mixer was operated at temperatures between 18 and 80C with comminute leaves of mate in the size range from 4.9x104 to 5.7x104m. The experimental kinetic curves of solute concentration in the aqueous phase revealed a diffusion coefficient of soluble species through the leaves in the magnitude of 10121013m2/s. A negligible influence of agitation and significant effects of solvent temperature and particle size on the rate of extraction of soluble matter were experimentally observed. The kinetics of infusion of mate leaves and the influence of the investigated factors were correctly reproduced by two simplified differential equations referred to as the equilibrium-dependent and diffusion-dependent extraction models. PRACTICAL APPLICATIONS Around US$1 billion is the overall value that emerged from the activities of cultivation, manufacturing and trade of mate leaves involving more than 70 countries across the continents. Despite these positive aspects, the aromatic and bioactive properties of mate could be better explored to obtain several commercial derivatives that would increase the economic impact of this commodity at a global scale. However, the development of most of these new products depends on the availability of the powder extract of mate, which is typically obtained by solidliquid extraction with hot water. In this framework, the results obtained in the current investigation can be applied as a guideline to design and operate industrial units of mate extraction in order have a maximum extraction yield at the lowest operating cost.