陈年普洱茶特征风味成分分析

采用顶空-固相微萃取-气质联用法测定陈年普洱茶中挥发性组分,其中烷烃类化合物含量较高,但它对茶叶香气几乎没有贡献,为此陈年普洱茶香气以芳烃类及其衍生物和萜烯类化合物为主,以酯类及其衍生物为辅。芳烃类及其衍生物以2,2',5,5'-四甲基联苯和1,2,3-三甲基-4-丙烯基-萘为主,萜烯类化合物以α-雪松烯和长叶烯两种异构体为主,并以α-雪松烯含量作为陈年普洱茶的检测指标。陈香味关联成分1,2,3-三甲氧基苯的含量随着萃取温度的提高而增加,最高约1.73%。同时采用比色法测得普洱茶的茶多酚、总黄酮、可溶性总糖及游离氨基酸含量分别为50.87、11.7、5.09、1.69 mg·g^-1。

Analysis on Characteristic Flavor Components of Aged Pu-erh Tea

Volatile compounds of aged Pu-erh tea were analyzed by solid-phase micro-extraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS). Alkanes were the most abundant volatile components in aged Pu-erh tea, however, it contributes scarcely to the aroma of tea. Aromatic hydrocarbons and their derivatives and terpenes were two major aromatic groups characterized, then the esters and their derivatives. Aromatic hydrocarbons and their derivatives are mainly consisted of 1,1'-Biphenyl, 2,2',5,5'-tetramethyl- and Naphthalene, 1,2,3-trimethyl- 4-propenyl-, (E)-, terpene compound are mainly consisted of α-cedrene and longifolene, and the relative content of α-cedrene was selected as the index for analyzing aged Pu-erh tea. The content of the key constituents of age-aroma, 1,2,3-Trimethoxybenzene was increased with the raise of temperature, and the highest relative abundance of 1,2,3-Trimethoxybenzene is about 1.73%. The contents of polyphenols, total flavonoids, total soluble saccharide and free amino acid were 50.87, 11.7, 5.09 and 1.69 mg·g^-1, respectively, which were measured by colorimetric method.