Some of the changes occurring during storage of tea are described. Teas are often subject to varying periods of 3-6 months of storage from the time of production to reaching consumers. The changes which occur during storage have been studied by several workers, who have identified factors which affect the characteristics of tea. Among these are the increase of moisture accompanied by growth of microorganisms (1), increase in thearubigins and extractable caffeine, and decline in theaflavin levels (2-4). An important factor in the decline of theaflavin levels in stored tea is the residual polyphenol oxidase and peroxi-dase activity in processed black tea. It was also shown that storage of tea under extreme conditions of low temperature, low moisture,and low oxygen availability, as well as acid treatment of tea during the fermentation stage of manufacture, led to a marked reduction in residual enzyme activity and a decrease in the rate of deterioration of the theaflavin during storage.
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