Adsorption and desorption characteristics of epigallocatechin-3-gallate from discarded green tea leaves on macroporous resin

Green tea ( Camellia sinensis ) is intensely consumed all over the world and tea leaves discarded from production are a rich source of catechins, especially epigallocatechin-3-gallate (EGCG). This study aimed to perform preparative separation of EGCG from green tea waste by using macroporous resin and to reveal adsorption and desorption characteristics. Nine types of resins were compared for their adsorption and desorption capacities and desorption rate of EGCG, and NKA-2 was found the most suitable resin for the purpose. Adsorption isotherms were evaluated at 25°C, 35°C and 45°C. Experimental data was well described with pseudo-second order kinetics model and fitted best to the Langmuir model in tested temperatures. In dynamic separation process, 83% of adsorbed EGCG was recovered from the resin by using 70% ethanol. It has been thought that using macroporous resin can be an effective way of EGCG separation from green tea waste for commercial purposes.