Pressure-dependent kinetic modeling of solid-liquid extraction of the major green tea constituents

The main aim of this work was to model the extraction process of the major green tea constituents in order to quantify the influence of the pressure on extraction kinetics. The kinetics of solid-liquid extraction of total catechins and caffeine at several pressures (200, 300, 400 and 500 MPa) were carried out using 50% aqueous ethanol. So and Macdonald's model involving the concept of broken and intact cells in order to describe three successive extraction periods: an initial very fast washing stage, a fast diffusion stage and a slow diffusion stage, was successfully developed for describing the mechanism of solid-liquid extraction of the major green tea constituents under different pressures. From the modeling results, the influence of the pressure on the extraction yields of total catechins and caffeine of the various stages at equilibrium, and the mass transfer coefficient were identified. (C) 2014 Elsevier B.V. All rights reserved.