Abstract
Ascorbic acid (AA) content and ascorbate oxidase activity in the leaves of tea plants, Thea sinensis Linn., during growth were studied.
The reduced, dehydro and total AA contents in leaves were 152, 55 and 205 mg%, respectively. In middle summer, the lowest levels of reduced and total AA (28 and 95 mg%, respectively) and remarkably higher activity of ascorbate oxidase were observed. In winter, particularly in intense cold, the levels of reduced and total AA were the highest (297 and 362 mg%) and the ascorbate oxidase activity remarkably decreased. In early summer, the enzyme activity in buds was considerably lower than in leaves, particularly in those at the top position of tree.
Reduced AA content in leaves was found to decrease during storage. Loss of reduced AA in leaves stored at 4°C for 3 days was 93, 100 and 6% for early summer, middle summer and winter-leaves, respectively. Even after 20 day storage the loss in winter-leaves was only 20%. The stability of reduced AA in winter-leaves was found significantly higher than that in other seasons.
Approximately 96% of reduced AA content in the fresh leaves was retained in tea manufactured from winter-leaves, while about 36% remained in the heated tea.
