基于全二维气相色谱-飞行时间质谱法的黄精叶绿茶和龙井绿茶香气成分比较

Comparison of aroma components between Polygonatum leaves green tea and Longjing green tea based on comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry

目的 了解黄精叶绿茶主要香气成分,探明黄精叶绿茶和龙井绿茶的香气成分差异。方法 采用全二维气相色谱-飞行时间质谱法(comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry,GC×GC-TOF MS)分析两种绿茶香气成分组成与相对含量。结果 两种绿茶共鉴定出332种成分,归属为醇、酮、饱和烷烃、烯烃、醛、酯、吡嗪、芳烃、酸、胺、醚、环氧烷、环烷烃、酚、呋喃、呋喃酮、酰胺、吡咯啉、酸酐、硫化物、卤代烃、含氮化合物、含氧化合物、杂环化合物、氮氧化物等26类化合物。黄精叶绿茶鉴定出225种挥发性成分,龙井绿茶鉴定出200种挥发性成分,共有成分93种。醇类均为含量最高的种类,占黄精叶绿茶香气总含量的26.47%,占龙井绿茶香气总含量的30.94%。黄精叶绿茶的醛类含量仅次于醇类,占21.75%,而龙井绿茶的烯烃类含量仅次于醇类,占14.33%。结论 38种挥发性化合物在二者中相对含量较高,其中戊醇、苯甲醇、苯甲醛在黄精叶绿茶中相对含量较高,对其香气品质可能具有直接影响。与之不同的是,龙井绿茶中反式-2-戊烯-1-醇、(R)-1-甲基-5-(1-甲基乙烯基)环己烯等挥发性化合物相对含量较高。同时相对含量不高的低阈值挥发性化合物也可能是形成黄精叶绿茶香型的关键香气(如α-紫罗兰酮等)。这有利于后续深入研究黄精叶绿茶香气成分的化学组成,为黄精叶制成茶叶提供数据支持。

Objective To understand the main aroma components of Polygonatum leaves green tea,and explore the difference of aroma components between Polygonatum leaves green tea and Longjing green tea.Methods The aroma compositions and relative content of 2 kinds of green tea were analyzed by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry(GC×GC-TOF MS).Results A total of 332 components were identified in the 2 kinds of green tea,which were classified into 26 compounds including alcohol,ketone,saturated alkanes,alkenes,aldehyde,ester,pyrazine,aromatic hydrocarbons,acid,amine,ether,epoxy silane,cycloparaffin,phenol,furan,furan ketone,amide,pyrroline,anhydride,sulfide,halogenated hydrocarbon,nitrogen compounds,oxygen compounds,heteroatom compounds,and nitrogen oxide.A total of 225 volatile components were identified in Polygonatum leaves green tea,and 200 volatile components were identified in Longjing green tea,a total of 93 components in common.Alcohols were the most abundant components,accounting for 26.47%of the total aroma content of Polygonatum leaves green tea and 30.94%of the total aroma content of Longjing green tea.The aldehydes in Polygonatum leaves green tea were next to alcohols,accounting for 21.75%,and Longjing green tea was olefins,accounting for 14.33%.Conclusion The relative content of 38 kinds of volatile compounds are relatively high,among which the relative content of amyl alcohol,benzyl alcohol and benzaldehyde are higher in Polygonatum leaves green tea,which may have direct influence on its aroma quality.In contrast,Longjing green tea has a high relative content of trans-2-pentene-1-ol,(R)-1-methyl-5-(1-methylvinyl)cyclohexene and other volatile compounds.At the same time,low threshold compounds with low relative content may also be the key aroma of Polygonatum leaves green tea(such asα-ionone,etc.).It is conducive to further study on the chemical composition of aroma components of green tea,provide data support for the preparation of Polygonatum leaves into tea.