OCCURRENCE AND DISTRIBUTION OF LIPOXYGENASE IN CAMELLIA-SINENSIS (L) KUNTZE,O AND THEIR CHANGES DURING CTC BLACK TEA MANUFACTURE UNDER SOUTHERN INDIAN CONDITIONS

The optimal activity of tea lipoxygenase was found to be at pH 7.5 and 9.0, indicating the presence of two types of isoenzymes. Tea lipoxyge nase was inhibited by cyanide and a small fraction appeared to be quit e heat stable. Clonal and seasonal variations in lipoxygenase activity was significant. An increase in lipoxygenase activity was observed wi th leaf maturity. The lipoxygenase activity decreases with age from pr uning and increases with an increase in plucking interval. The changes of lipoxygenase activity during CTC manufacture revealed that it incr eased with the degree of withering and upon rolling. However, a gradua l decline was recorded during the fermentation and drying processes. T he residual lipoxygenase activity in black tea is expected to affect i ts quality on storage. (C) 1998 Society of Chemical Industry.