普洱茶后发酵中的香气成分变化分析

为探索普洱茶后发酵过程中各阶段茶样香气成分变化，跟踪普洱茶的整个后发酵过程，采用同时蒸馏萃取法提取所取茶样的香气成分，采用气质联用法对其进行分析，同时对茶样进行感官评定。经气质联用分析鉴定，共鉴定出香气成分65 种，其中碳氢化合物11 种，醇类化合物10 种，醛类化合物13 种，酮类化合物10 种，酸类化合物6 种，酯类化合物6 种，其他类化合物9 种；晒青毛茶的香气组分以芳樟醇、4- 苯基吡啶、叶绿醇(植醇)、3,7 二甲基-1,6- 辛二烯-3- 醇、n- 棕榈酸、4- 甲基-2- 丙基-1- 戊醇等为主，普洱熟茶出堆样的香气组分以n-棕榈酸、二氢猕猴桃内酯、二氢海葵内酯、二乙基-2- 甲基十三醇、反式- β- 大马酮等为主。在整个发酵过程中，各茶叶样品中的香气组分，除醇类化合物和其他类化合物相对含量总体上逐渐减少外，酮类、醛类、酸类、酯类等物质的相对含量总体上都处于增加状态，甲基化物质的种类和数量随着后发酵的进行都呈增加趋势。

Analysis of Changes in Aroma Components of Pu-erh Tea during Post-fermentation Process

Objective: To reveal the origin of aroma substances in ripe Pu-erh tea and provide guidance for the production of ripe Pu-erh tea by exploring the changes in aroma components during post-fermentation process. Methods: Simultaneous distillation-solvent extraction was applied to extract aroma compounds from Pu-erh tea samples at different post-fermentation stages, and the aroma compounds were analyzed by GC-MS. Besides, these Pu-erh tea samples were subjected to sensory evaluation. Results: 65 kinds of aroma components were totally identified in Pu-erh tea samples at different post-fermentation stages, including 11 hydrocarbon kinds, 10 alcohol kinds, 13 aldehyde kinds, 10 ketone kinds, 6 acid kinds, 6 ester kinds, and 9 other compound kinds. The main aroma components of sunshine withering tea were linalool, 4-phenyl-pyridine, phytol, 3,7 dimethyl-1,6- octadiene-3-alcohol, n-palmitic acid, and 4-methyl-2-propyl-1-pentanol, and those of ripe Pu-erh tea were npalmitic acid, dihydro-kiwi lactone, dihydro lactone anemones, diethyl-2-13 methyl alcohol, and trans-keto-β-malaysia. The relative contents of ketones, aldehydes, acids, and esters increased, but those of alcohols and other compounds decreased over the post-fermentation process. Both type and quantity of methylated substances presented rising trend with the post-fermentation extending. The sensory evaluation indicated that the change from clean aroma to stale flavor occurred in the process from sunshine withering tea to ripe Pu-erh tea.