Examination of conditions for the efficient extraction of various functional ingredients from tea leaves (Camellia sinensis L.) using a tea infuser, 'Rich plus' (RICH+®)

Abstract

To utilize the functional ingredients of tea leaves, we examined conditions for rapidly extracting O-methylated catechins, epigallocatechin (EGC) and theanine using a tea infuser, "Rich plus (RICH + ®)". Nineteen mg of O-methylated catechins per cup (120 mL) could be extracted with water at 94°C in 20 seconds with stirring using 1.9 g of "Benifuuki" green tea that contained 1.7% of O-methylated catechins by weight. Thirty-nine mg of EGC and an EGC/EGCG ratio of 2.5 could be extracted at 10°C in 30 seconds with stirring using 1.5 g of 'Yutakamidori' green tea in which the EGC/EGCG ratio was about one. Twenty mg of theanine could be extracted at 65°C in 20 seconds with stirring using 1.7 g of 'Saemidori' green tea that contained 1.4% by weight theanine. These quantities correspond to approximately half the daily recommended intake of O-methylated catechins and EGC that the anti-allergic action and immunostimulating action have been described in the manuscripts.