Catechin stability of EGC- and EGCG-enriched tea drinks produced by a two-step extraction procedure

Catechin content of green tea drinks commercially available is reported to be very low in comparison with tea traditionally prepared, due to catechins conversion to their corresponding epimers during production. The purpose of this present study was to produce catechin-enriched tea drinks according to a two-step brewing procedure and to verify the catechin stability of those enriched drinks during storage. Those results confirmed that it is possible to produce EGC- and EGCG-enriched tea drinks regardless of the green tea used. Good extraction efficiencies were reached for the first and second extraction steps with catechin extraction yields ranging from 63.6% to 84.8%. Furthermore, it appeared that the catechin content in the two enriched tea drinks demonstrated a great stability since no significant degradation occurred within 8 weeks of storage. This simple two-step extraction procedure could be considered as an interesting way to produce enriched green tea drinks with more potent and stable bioactive catechins.