白茶贡眉的香气组成与关键呈香成分分析

Volatile Components and Key Aroma-active Compounds in Gongmei White Tea

以全二维气相色谱-飞行时间质谱(two-dimensional gas chromatography-time-of-flight-mass spectrometry,GC×GC-TOFMS)技术结合气相色谱-嗅闻-质谱(gas chromatography-olfactometry-mass spectrometry,GC-O-MS)技术研究贡眉的香气组成及关键呈香成分。结果表明:从贡眉样品中共鉴定出236种挥发性化合物,以醛类(38.46%)和醇类(25.58%)为主,相对含量较高的有苯甲醛(147.27‰)、反-2-己烯醛(90.14‰)、芳樟醇(79.80‰)、苯乙醇(50.76‰)、2-戊烷基呋喃(46.23‰)、香叶醇(39.06‰)、水杨酸甲酯(37.80‰)、二甲基硫醚(36.69‰)、正癸烷(31.68‰)、正己醛(29.39‰)、苯乙醛(25.06‰)和苯甲醇(22.15‰)等;GC-OMS检测到26种香气活性物质,其中鉴定出21种,包括醇类9种、醛类5种、酮类4种、酯类2种和芳香烃类化合物1种;这些香气物质主要呈现清香(或青气)及令人愉悦的花香、果香或甜香。GC×GC-TOFMS和GC-O-MS结果的联合分析表明,高比例的呈现天然清香、花果香或甜香的醇类和醛类香气成分是形成贡眉香气品质的基础。本研究有助于了解贡眉的香气品质化学,为在加工实践中提高贡眉的香气品质提供理论依据。

In this study,the volatile components and key aroma-active compounds of Gongmei white tea were comprehensively analyzed using two-dimensional gas chromatography-time-of-flight-mass spectrometry(GC×GC-TOFMS)combined with gas chromatography-olfactometry-mass spectrometry(GC-O-MS).A total of 236 volatile compounds were identified,mainly including aldehydes(38.46%)and alcohols(25.58%),and the major volatile components were benzaldehyde(147.27‰),(E)-2-hexenal(90.14‰),linalool(79.80‰),phenethyl alcohol(50.76‰),2-pentyl-furan(46.23‰),geraniol(39.06‰),methyl salicylate(37.80‰),dimethyl sulfide(36.69‰),decane(31.68‰),hexanal(29.39‰),phenethyl alcohol(25.06‰),and benzyl alcohol(22.15‰).GC-O-MS analysis revealed 26 aroma-active compounds,of which 21 compounds were identified,including nine alcohols,five aldehydes,four ketones,two esters and one aromatic hydrocarbon;and these odorants mostly presented clean(green),fresh,floral,fruity,or sweet aromas.Taken together,the GC×GC-TOFMS and GC-O-MS results showed that high proportions of alcohols and aldehydes responsible for natural green,fresh,floral,fruity,or sweet aromas could form the basis for the aroma characteristics of Gongmei.The results in this study will contribute to in-depth understanding of the aroma quality chemistry of Gongmei,and provide a theoretical guidance for improving the aroma quality of Gongmei in processing practices.