Effect on the content of catechins in instant tea for adding gallic acid

Oolong tea, green tea and black tea were used as raw material to produce instant tea in this study. The gallic acid was added during the extraction procedures, and the effect of adding gallic acid (GA) on the content of ester-catechin and epigallocatechin gallate (EGCG) in instant tea was investigated. The results of this study showed that the application of GA increased the concentration of ester-catechin as well as EGCG in oolong tea, whereas decreasing concentration of catechins in green tea, black tea compared with control.