White Tea

White tea is a poorly defined category. The term “white tea” first appeared in a monograph entitled “A Grand Overview on Tea” which was written by emperor Hui Zhong of the Song Dynasty in 1107 AD. The emperor mistakenly thought a weakened mutant of tea plant with delicate light-colored leaves which had lost its ability to reproduce to be a rare species of tea trees. Nowadays, white tea is produced from the same tea leaves as those used for green tea, black tea and oolong tea, but without heat inactivation. The manufacturing methods vary. One popular protocol of production is to let the fresh tea leaves air-dry at 28-30º C in 65-70% relative humidity for 34-38 hours to reduce their water contents to 14-16% in dry weight. Then the leaves are hand-selected and further dried in low heat or under the sun. Since the polyphenol oxidase of the tea leaves has not been inactivated, the tea catechins in white tea undergo continuous oxidation at uncontrolled rates during production and storage. Its residual EGCG levels vary widely and are generally very low in the samples purchased on the market.