Abstract
Chemical changes of ascorbic acid in the procedures of black tea manufacture were investigated. Ascorbic acid in tea leaves was oxidized and decreased in amount in all stages of manufacture and two thirds of ascorbic acid were oxidized beyond 2,3-diketogulonic acid. L-Threonic acid, glyceric acid, glycolic acid and oxalic acid were detected as oxidized products of ascorbic acid from the fermented tea leaves, to which much ascorbic acid was added. It was therefore, supposed that a part of ascorbic acid in tea leaves was oxidized mainly by polyphenol oxidizing enzymes during the black tea fermentation, followig the pathway of the decomposition of ascorbic acid which was studied and reported by these authors.
