溶剂辅助风味蒸发-气相色谱-质谱联用法分析普洱茶干茶与茶汤的挥发性成分

Analysis of volatile components of tea leaves and infusion from Pu-erh tea by solvent-assisted flavor evaporation combined with gas chromatography-mass spectrometry

目的比较普洱茶干茶和冲泡后茶汤的挥发性成分,并测定特征性香气物质甲氧基苯的绝对含量。方法采用溶剂辅助风味蒸发对3个不同年份的普洱茶干茶和冲泡后茶汤的挥发性成分进行提取,运用气相色谱-质谱联用技术分析挥发性组分,并利用气相色谱峰面积外标法,测定1,2,3-三甲氧基苯和1,2,4-三甲氧基苯的绝对含量。结果从普洱茶中共鉴定出70种挥发性物质,干茶含70种,茶汤含45种;鉴定出的化合物包括甲氧基苯类、酸类、酮类、酯类、内酯类、醇类、碳氢类、醛类、醚类,其中含量最多的物质是甲氧基苯类化合物;干茶中1,2,3-三甲氧基苯和1,2,4-三甲氧基苯的含量分别为7.78μg/g和5.37μg/g,茶汤中为3.45μg/g和2.73μg/g。结论冲泡后茶汤挥发性成分明显减少,2种甲氧基苯化合物含量明显降低,本研究可为普洱茶中挥发性成分的含量测定提供参考。

Objective To compare the volatile components of tea leaves and infusion from Pu-erh tea and determine the absolute content of characteristic aroma components （methoxyphenolic compounds）. Methods The volatile components of tea leaves and infusion from Pu-erh tea in 3 different years were analyzed by solvent assisted flavor evaporation （SAFE） combined with gas chromatography-mass spectrometry （GC-MS）. The absolute content of characteristic aroma components of Pu-erh tea （1,2,3-trimethoxybenzene and 1,2,4-trimethoxybenzene） were determined by external standard method of gas chromatography. Results A total of 70 volatile compounds were identified in Pu-erh tea, including methoxyphenolic compounds, acids, ketones, esters, lactones, alcohols, hydrocarbons, aldehydes, ether. Seventy compounds were found in tea leaves and 45 compounds were found in tea infusion, respectively. Methoxyphenolic compounds were the most abundant compounds in both leaves and infusion. The absolute content of 1,2,3-trimethoxybenzene and 1,2,4-trimethoxybenzene in leaves were 7.78μg/g and 5.37 μg/g, and the content in infusion were 3.45μg/g and 2.73 μg/g, respectively. Conclusion The volatile components of tea infusion are significantly reduced, and the absolute content of two methoxyphenolic compoundsalso decrease significantly in infusion. This paper can provide references for the determination of volatile components in Pu-erh tea.