普洱茶晒青样游离氨基酸和色泽差异研究

为探讨游离氨基酸和色值在普洱茶晒青样产地及古树茶和台地茶中的差异，分析了来自云南西双版纳州、临沧市普洱茶晒青样中18 种游离氨基酸组分含量，用色差仪测定茶汤色值（L*、a*、b*），并进行方差分析、主成分分析。结果表明：晒青样中游离氨基酸组分含量在两地间有明显差异，西双版纳样品中茶氨酸、天冬氨酸、谷氨酸、精氨酸等主要鲜味氨基酸含量高于临沧样品。氨基酸主成分分析对西双版纳和临沧晒青样可以很好区分。台地茶游离氨基酸总量、天冬氨酸、谷氨酸、茶氨酸、组氨酸含量均比古树茶高，精氨酸含量比古树茶低，其中氨基酸总量、谷氨酸、精氨酸、组氨酸差异显著，二者也是在主要鲜味氨基酸上存在差异。两地晒青样汤色存在差异，西双版纳样品L*、b*值较临沧大，a*值较小。古树茶与台地茶汤色差异不明显。

Differences in Free Amino Acids and Color in Raw Pu-erh Tea Samples of Different Origins

The composition of free amino acids and color in raw Pu-erh teas of different origins were comparatively
investigated. The contents of eighteen free amino acids (Asp, Thr, Ser, Glu, Gly, Ala, Cys, Val, Met, Ile, Leu, Tyr, Phe, Lys,
His, Arg, Pro, and Thean) in Pu-erh raw teas and tea infusion color (brightness L*, and chromaticity values Δa* and Δb*)
from Xishuangbanna Prefecture and Lincang City, Yunnan province, China, respectively, were analyzed by automatic amino
acid analyzer, HPLC and color difference meter. Variation analysis and principal component analysis (PCA) were used for
data analysis. The results showed that the free amino acids had distinct geographical features. The contents of main flavor
amino acids such as Thean, Asp, Glu and Arg were higher in samples from Xishuangbanna than in those from Lincang.
Use of PCA provided a clear distinction of the samples from the two regions. The contents of total amino acids, Asp, Glu,
Thean and His were higher in tableland tea than in old plant tea, but the content of His was lower. Furthermore, there were
significant differences in the contents of total amino acids, Glu, His, and Arg between tableland tea and old plant tea, as well
as differences in main flavor amino acids, L*, a*and b* also displayed significant difference between the two geographic
origins. L* and b* were higher but a* was lower in samples from Xishuangbanna. No significant difference in the color of
tea infusion existed between tableland tea and old plant tea.