Novel studies on membrane extraction of bioactive components of green tea in organic solvents: part I

Membrane extraction of the bioactive components of green tea in an organic solvent has been investigated using different nanofiltration membranes. Different concentrations of ethanol (10%, 20%, 50% and 80%) were used as the organic solvent. Membrane separation performance of bioactive components of green tea showed some changes in flux and solute rejection with negligible change in membrane stability. Special attention was focused on the removal of caffeine from the solution mixture of the green tea extract while retaining the group of catechins known as polyphenols. A series of tests with Various membranes using higher ethanol concentrations (e.g. 80%) gave highest rejection of catechins with lower rejection of caffeine for G-10 and G-20 membranes, respectively. The rejection using HC-50 and HR98PP membranes were fairly good but the pure ethanol fluxes under the same pressure (5.0 MPa) were not promising for this solvent. (C) 2000 Elsevier Science Ltd. All rights reserved.