Production of green tea EGC- and EGCG-enriched fractions by a two-step extraction procedure

The aim of the present work was to test the feasibility of a two-step extraction procedure to fractionate EGCG and EGC from green tea. This work was based on previous observations that there was a variable interdependence between the brewing duration and the brewing temperature on catechin concentrations: EGC being a time-dependent compound while EGCG being a time/temperature-dependent compound. It appeared from these results that it was possible to produce from green tea, on a simple way with adding no organic solvent, an EGC-enriched extract (78.9% total catechins) in the first step and an EGCG-enriched extract (47.6% total catechins) in the second step. The two-step brewing procedure based on the temperature-dependent solubilization of both major catechins, EGC and EGCG, allowed the production of such extracts by decreasing ash and EGC contents during the second step extraction. (c) 2007 Elsevier B.V. All rights reserved.