Extractability of tea catechins as a function of manufacture procedure and temperature of infusion

Green teas were made by different inactivation procedures ranging from steaming, thermal inactivation by heating in an oven or microwave-mediated inactivation, followed by either unidirectional or bi-directional rolling and drying. Teas were infused at different temperatures (80 and 100 °C) and the tea ceremony way of infusing, and analyzed for tea catechins and xanthine alkaloids by HPLC. Teas manufactured following microwave inactivation, bi-directional rolling and drying showed higher catechins and methyl xanthines by HPLC, and extracted higher catechins and caffeine in infusions. Catechins, especially EGCG, EGC, and EC, showed marked differences when extracted at different temperatures. Considerable amounts of catechins and caffeine can be extracted each time when the same leaf is infused repeatedly 4-5 times, as done in Japan for making ceremonial teas.