Abstract: In this study,in order to explore the possibility of improving green tea quality with exotic tannase,different concentrations of tannase were mixed with tea leaves in the rolling period of the traditional tea process,and biochemical compositions were analysed in samples of made tea. The results showed that the total content of polyphenols has no substantial difference between the control and the treated samples,while the content of amino acid rises slightly in treated sample compared with that in the control sample. A prominent finding was obtained that tannase application substantially decreases the proportion of catechin-gallate including epigallocatechin gallate(EGCG) in total catechins but increases some taste-sensitive amino accids such as Glu. These changes have positive effects on improving tea quality,which implies that the harshness of green tea could be reduced and mellowness could be enhanced by adding some quantity of tannase in tea processing from fresh leaves plucked in summer season.

Key words: exotic tannase, green tea, flavor, catechin-gallate, amino acid