Vitamin C in Black Tea

Abstract

The chemical change of ascorbic acid on the black tea manufacture was investigated by the 2, 4-dinitrophenylhydrazine method. The results were as follows : Ascorbic acid was oxidized in the withering process and disappeared when rooling. Dehydroascorbic acid increased in the withering process and decreased in the fermentation process. 2, 3-Diketogulonic acid increased by the rooling and in the fermentation process.
These changes were accelerated by the-heating. The total of them in black tea was less than the initial content in tea leaves. It is, therefore, supposed that ascorbic acid was changed to some substances through dehydro ascorbic acid and 2, 3-diketogulonic acid on the black tea fermentation process.