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| Effects of rapid ageing technology on the aroma quality of white tea using gas chromatographymass spectrometry/mass spectrometry combined with chemometrics |
| QI Dandan1, CHEN Wei1, MIAO Aiqing1, WANG Wenwen2, PANG Shi1, MA Chengying1* |
(1. Tea Research Institute, Guangdong Academy of Agricultural Science/Guangdong Key Laboratory of Tea Plant Resources
Innovation & Utilization, Guangzhou 510640, China; 2. Agilent Technologies (China) Co. Ltd., Beijing 100102, China)
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Abstract To investigate the effects of rapid ageing technology on the aroma quality of white tea, the Yinghong No. 9 white tea of the same batch stored in a natural environment was used as a control group (CK), and that one stored in a rapid ageing environment was used as a treatment group. The aroma components of the white tea samples in the two different storage conditions were extracted by a headspace solid-phase micro-extraction (HS-SPME) technique and were analyzed by gas chromatography-mass spectrometry (GC-MS) combined with chemometric software Mass Profiler Professional (MPP). Moreover, sensory analysis was performed to evaluate their aroma quality. Results showed that there were significant differences on the aroma type, composition and content of aromas between these two kinds of white tea. The CK had a sweet and green aroma, while the rapid ageing white tea (the treatment group) was featured with stronger sweet aroma than the CK. All entities extracted from raw data through deconvolution were subjected to principal component filter with MPP, including coefficient of variation (CV＜25%), fold change (FC≥2), significance analysis (P＜0.01). By matching mass spectrum and retention index (RI), 25 differential entities were identified finally. The result from principal component analysis (PCA) showed that the 25 entities explained 99.79% of total variance on PC1 and well reflected the difference between the CK and treatment group. Among these 25 components, esters, ketones, hydrocarbons were the major chemical classes. Ten components existed just in the treatment group, including n-hexanoic acid, 2-decanone, 3- nonen-2-one, 3-penten-2-one-4-methyl, and so on. Six esters existed only in the CK, including hexadecanoic acid methyl ester, octanoic acid methyl ester, acetic acid 2-phenylethyl ester, nonanoic acid methyl ester, heptanoic acid methyl ester, hexanoic acid 3-hexenyl ester. Nine components existed in both the CK and the treatment group, with the contents of toluene and 1-methyl-4-(1-methylethenyl)-benzene rising in the treatment group, while the contents of α-ionone, β-ionone, hexanoic acid methyl ester, 2-pentadecanone, 6,10,14-trimethyl, butylated hydroxytoluene, tridecane 3-methyl, and 6-isocedrol declining in the treatment group. In conclusion, rapid ageing technology can accelerate transformation of volatile compounds in white tea to some extent, thus to promote the aroma quality of white tea.
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Published: 25 November 2018
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气相色谱-串联质谱结合化学计量学分析快速陈化对白茶香气的影响
为考察快速陈化对白茶香气品质的影响，以在自然条件下存放相同时间的英红九号白茶作为对照，采用顶空固相微萃取和气相色谱质谱分析方法结合化学计量学软件MPP（mass profiler professional）分析比较自然陈化和快速陈化白茶在香气成分和组成上的差异；结合香气感官审评结果分析讨论快速陈化对白茶香气品质的影响。结果表明，2 种白茶在香气表现、香气物质组成和含量上均存在显著差异：自然陈化白茶香气以尚甜带青为主，快速陈化白茶以甜香较浓为主。经过严格的化合物筛选（组内变异系数＜25%，P＜0.01，差异倍数≥2）和定性（质谱图和保留指数比对）分析，最终得到25 种香气差异化合物；经过主成分分析（principal component analysis, PCA）表明，这些化合物在PC1上的贡献率为99.79%，能极好地代表2 组样品之间的差异。25 种化合物以酯类、酮类和烃类化合物为主，其中：有10 种化合物仅存于快速陈化白茶中，且以甜香和果香的己酸、2-癸酮、3-壬烯-2-酮、4-甲基-3-戊烯-2-酮为主；6 种酯类化合物仅存于自然陈化白茶中，包括棕榈酸甲酯、辛酸甲酯、乙酸苯乙酯、壬酸甲酯、庚酸甲酯、己酸-顺-3-己烯酯；有9 种化合物在2 种白茶中都存在，其中甲苯和4-异丙烯基甲苯在快速陈化白茶中含量上升，α-紫罗酮、β-紫罗酮、己酸甲酯、植酮、丁羟甲苯、3-甲基十三烷和6-异雪松醇在快速陈化白茶中含量均下降。综上表明，快速陈化技术能在一定程度上加速白茶香气物质的转化，可在短时间内改善白茶的香气品质。
关键词：
白茶,
快速陈化,
香气,
顶空固相微萃取,
气相色谱质谱联用
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