The HPLC–UV method with PITC pre-column derivatization was
improved for the simultaneous determination of free amino acids
in Pu-erh tea. This method is accurate, precise, rapid and robust.
The major amino acids including Asp, Glu, Arg, Ala, Thea, and Tyr
were detected in all tea samples. However, the amino acid profiles
were significantly different among sun-dried tea leaves, Pu-erh
raw tea, and Pu-erh ripened tea. Moreover, microbial fermentation
process caused the changes of amino acid profiles and AA content
in Pu-erh ripened tea. Therefore, microbial fermentation process
would impact on the quality and safety of Pu-erh ripened tea.
However, the relationship between the changes of amino acids,
AA accumulation and the development of aroma and taste in Puerh
tea during microbial fermentation need to be investigated in
future.