乌龙茶ATD-GC-MS检测方法优化及不同等级肉桂乌龙茶香气成分分析

对全自动热脱附-气相色谱-质谱法检测肉桂乌龙茶挥发性物质的方法进行优化，并结合化学计量方法分析3 个等级（特级、一级、二级）肉桂乌龙茶的香气成分。应用单因素试验结合响应面分析对全自动热脱附方法中吸附温度、吸附时间、冷阱温度参数进行优化，确定最优参数为吸附温度55 ℃、吸附时间37 min、冷阱温度－29 ℃。对不同等级肉桂乌龙茶的香气成分进行检测分析，共鉴定出香气成分173 种，其中共有香气成分90 种。基于肉桂乌龙茶香气成分的峰面积建立偏最小二乘判别分析模型，可区分3 个等级的肉桂乌龙茶样品；并通过层序聚类分析探讨47 种特征香气成分在3 个等级肉桂乌龙茶的分布规律。本研究为肉桂乌龙茶香气品质和等级鉴别提供一定的理论依据。

Optimization of an Automatic Thermal Desorption-Gas Chromatography-Mass Spectrometry Detection Method for Oolong Tea and Analysis of Aroma Components in Different Grades of Rougui Oolong Tea

An automatic thermal desorption-gas chromatography-mass spectrometry (ATD-GC-MS) method was developed, optimized and applied in combination with chemometrics for the detection of the aroma components of three different grades (superfine, grade A and grade B) of Rougui oolong tea. In automatic thermal desorption, the operating parameters adsorption temperature, adsorption time and cold trap temperature were optimized by single factor experiments and response surface methodology. The optimal parameters were determined as follows: adsorption temperature of 55 ℃, adsorption time of 37 min and cold trap temperature of ?29 ℃. A total of 173 aroma components were identified, 90 of which were common to all the three grades. In addition, a partial least squares discriminant analysis (PLS-DA) model to distinguish the different grades of Rougui oolong tea was established based on the peak areas of the aroma components of Rougui oolong tea. and the distribution of 47 characteristic aroma components in the three different grades of Rougui oolong tea was discussed by hierarchical cluster analysis. The results of this study could provide a theoretical basis for the identification of the aroma quality and grade of Rougui oolong tea.