Changes in O-methylated Catechin and Chemical Component Contents of 'Benifuuki' Green Tea (Camellia sinensis L.) Beverage under Various Extraction Conditions

We examined the effects of extraction conditions on the anti-allergic components, epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3″Me) and strictinin during the manufacture of anti-allergic ‘Benifuuki’ green tea beverage. Ester-type catechins were extracted at a constant ratio to total catechin content and were easy to epimerize. After a long extraction time at above 90°C, large amounts of epimer were rapidly pro-duced. Moreover, the ratio of EGCG3″Me to polyphenol content was nearly constant, indicating that this ratio could be an essential index during the manufacture of tea beverages. EGCG3″Me easily isomerizes at temperatures above 95°C. From the ratios of EGCG3″Me to polyphenol, it was concluded that, at a fixed ex-traction temperature and 20-fold dilution (W/V), similar extraction efficiencies are obtained for extractions from 6 to 15min heated for 9min at 90°C and 95°C showed strong histamine release inhibitory effects. Ex-traction temperature strongly contributed to inhibitory effect volume had a limited effect. We suspect that extraction at high temperature promoted EGCG3″Me extraction efficiency and epimerization to GCG3″Me.