不同香气类型龙井茶香气组成及其相关组分比较

Aroma compositions and comparison of their related components of Longjing tea with different aroma types

本研究广泛收集龙井茶样品,基于感官分析表现出的嫩香、清鲜、尚高特征的香气类型分组,利用可控温的同时蒸馏萃取法(simultaneous distillation extraction, SDE)提取其香气物质,并结合气相色谱-质谱联用(gas chromatography-mass spectrometry, GC-MS)技术进行香气组分及特征的比较。结果显示:嫩香类、清鲜类及尚高类龙井茶类型间的香气组分在醇类、醛类、萜烯类、酮类、烷烃类、烯类、杂环类及酯类等化合物上表现出种类及相对含量的差异性。基于主要香气组分进行主成分分析(principal component analysis, PCA)的结果显示:1)龙井茶嫩香特征与香气组分中的苯乙烯、十六烷、3-甲氧基-1,2-丙二醇等化合物含量呈明显的正相关性;2)清鲜特征与(E)-β-金合欢烯、反-4-叔丁基环己醇、甲基茉莉酮酸酯含量呈明显的正相关性;3)尚高类龙井茶样品中的苯乙腈、苯乙酮、1,3-环己二烯-2,2,6-三甲基苯甲醛等组分含量较高。本研究可为龙井茶感官审评中的香气描述提供理论依据。

Longjing tea is a famous traditional tea in China and the aroma is an important factor in the quality evaluation of tea.In this study,Longjing tea samples were widely collected and explored by sensory evaluation,which dividing them into three aroma groups:tender aroma type,clean and refreshing aroma type,and approaching high aroma type.Then,simultaneous distillation extraction(SDE)and gas chromatography-mass spectrometry(GC-MS)were used for extraction and determination of aroma compositions.The result suggested that the aroma-characteristic compositions of Longjing tea with tender aroma,clean and refreshing aroma,and approaching high aroma,respectively,showed differences in types and relative contents of alcohols,aldehydes,terpenes,ketones,alkanes,alkenes,heterocycles,esters and so on.The results of principal component analysis(PCA)based on main aroma components showed that:1)The contents of styrene,cetane,3-methoxy-1,2-propanediol were significantly and positively correlated with the tender aroma of Longjing tea;2)the contents of(E)-β-farnesene,trans-4-tert-butylcyclohexanol and methyl jasmonate were significantly and positively correlated with the clean and refreshing aroma of Longjing tea;3)the relative contents of phenylacetonitrile,acetophenone,1,3-cyclohexadiene-2,2,6-trimethyl-benzaldehyde were higher in Longjing tea with approaching high aroma.This study provides a theoretical basis for aroma description in sensory evaluation of Longjing tea.