不同风味类型铁观音乌龙茶香气组成化学模式识别研究

doi:10.13305/j.cnki.jts.2018.03.005

摘要/Abstract

摘要： 铁观音乌龙茶按现行国家标准可划分“清香型”、“浓香型”和“陈香型”3种风味类型。本试验在对安溪铁观音收集和审评分类基础上,采用顶空固相微萃取和气相色谱-质谱联用法（HS-SPME/GC-MS）对各茶样进行香气成分检测,并通过主成分分析（PCA）、正交偏最小二乘判别分析（OPLS-DA）等可视化模式识别方法比较了不同风味铁观音新茶和不同质量等级铁观音陈茶香气组成的特征差异。结果表明：（1）铁观音新茶和陈茶香气组成的化学模式存在明显的类群区分。铁观音新茶相较陈茶具有更为丰富的香气组分,其中醇类、酯类和烯烃类化合物是铁观音新茶“清新”风味的主要赋香成分,而醛类和酮类化合物则是形成铁观音“陈香”风味的重要物质基础。橙花叔醇、吲哚、α-法呢烯、2-甲基丁酸-2-苯乙酯、己酸-顺式-3-己烯酯、2-甲基苯基甲酸甲酯、丁酸苯乙酯、2-甲基丙酸-2-苯基乙酯、2-苄基（苯甲基）异氰化、己酸异戊酯和香叶基丙酮可作为区分铁观音新茶和陈茶的主要特征香气成分。（2）铁观音新茶按其香气组成可划分为“显酸茶”、“正韵茶和青韵茶”、“浓香茶”3个茶样类群。带“酸香”风味的“显酸茶”主要与酯类化合物密切相关,而显“火香”风味的“浓香茶”香气成分多为长链缩合态化合物,且二者均较“正韵茶和青韵茶”香气组成更为丰富。（3）不同贮藏年份的铁观音陈茶香气组成无明显的类群区分,但有潜在的质量等级差异。高级铁观音陈茶的酯类化合物相对丰富,醛类和酮类化合物含量相对较低。该研究结果可为铁观音产品的分类鉴别和风味品质评价提供参考。

关键词: 铁观音, 乌龙茶, 香气成分, 模式识别

Abstract: According to the current national standards, Tieguanyin Oolong teas would be classified into three flavor types, Fresh-scent, Strong-scent and Stale-scent. In this experiment, Tieguanyin collected from their original regions (Anxi County) were categorized into several groups by preliminary sensory evaluation. Thereafter, aroma components in these tea samples were determined using headspace solid-phase micro-extraction and gas chromatography-mass spectrometry (HS-SPME/GC-MS), and their differences between new Tieguanyin (less than one year storage) with different flavor characteristics and old Tieguanyin (more than one year storage) with different storage time and quality ranks were compared through visual pattern recognition based on principal component analysis (PCA), and orthogonal partial least squares discriminant analysis (OPLS-DA) combined with other statistical methods. The results showed that aroma patterns of all tea samples could be obviously divided into two groups according to storage time. The total amount of aroma compounds was more abundant in new Tieguanyin than that of old Tieguanyin. Alcohols, esters and alkenes were the main compounds which contributed to the new fresh-scent flavor of new Tieguanyin, and aldehydes and ketones were the characteristic compounds of stale-scent flavor in old Tieguanyin. Nerolidol, indole, α-farnesene, 2-phenylethyl 2-methylbutanoate, cis-3-hexenyl hexanoate, formic acid, (2-methylphenyl) methyl ester, phenylethyl butyrate, phenylethyl isobutyrate, 2-tolylisocyanide, isopentyl hexanoate and geranyl acetone could be considered as the key markers to discriminate the two types of Tieguanyin. Moreover, new Tieguanyin could be also classified as Group 1 (Long-time withering), Group 2 (Medium-time withering and Short-time withering), and Group 3 (Strong-scent) based on their aroma constitutes. Aroma components were richer in tea samples from both Group 1 and Group 3 than those from Group 2. The acidic flavor of tea samples from Long-time withering was closely associated with ester compounds, while aroma components of tea samples from Strong-scent were mostly condensed compounds with long carbon chains. No obvious differences could be detected in old Tieguanyin, which had different storage time, but there were some potential differences among tea samples with high quality ranks. Tieguanyin of excellent sensory quality were relatively abundant in ester compounds, and low in contents of aldehydes and ketones. These results could provide references for classification, identification and quality evaluation of Tieguanyin products.

Key words: Tieguanyin, Oolong tea, aroma component, pattern recognition

中图分类号:

陈林, 林清霞, 张应根, 陈键, 王丽丽, 余文权, 尤志明. 不同风味类型铁观音乌龙茶香气组成化学模式识别研究[J]. 茶叶科学, 2018, 38(3): 253-262. doi: 10.13305/j.cnki.jts.2018.03.005.

CHEN Lin, LIN Qingxia, ZHANG Yinggen, CHEN Jian, WANG Lili, YU Wenquan, YOU Zhiming. Aroma Profiling of Tieguanyin Oolong Tea with Different Flavor Characteristics Based on Chemical Pattern Recognition[J]. Journal of Tea Science, 2018, 38(3): 253-262. doi: 10.13305/j.cnki.jts.2018.03.005.

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