基于GC-IMS的不同年份紧压白茶挥发性物质分析

Analyses of Volatile Compounds in Compressed White Tea of Different Years Based on GC-IMS

摘要:

应用气相-离子迁移谱技术对不同年份紧压白茶的挥发性物质进行分析，共鉴定出56种挥发性物质。采用主成分分析（principal component analysis，PCA）和线性判别分析（linear discriminant analysis，LDA）方法共筛选出20个特征挥发性物质，起主要贡献作用的物质是2-乙酰基呋喃、庚醛、E-2-辛烯醛、柠檬烯、2-苯基乙醇及异丁酸。其中，柠檬烯、2-苯基乙醇、异丁酸的含量和贮藏时间呈反比，而2-乙酰基呋喃、庚醛和E-2-辛烯醛的含量则和贮藏时间呈正比。进一步进行线性回归分析，建立贮藏时间（y）和主要特征挥发性物质峰强数据的预测模型方程， y=-0.03x₁+0.038x₂-0.09x₃-0.012x₄+0.002x₅+0.004x₆+0.022x₇+0.019x₈-0.018x₉-0.011x₁₀+0.005x₁₁-0.011x₁₂+0.000x₁₃-0.042x₁₄-0.015x₁₅+0.017x₁₆+0.033x₁₇+0.008x₁₈+0.008x₁₉-0.124x₂₀（其中x₁~x₁₃为未定性特征挥发性物质，x₁₄~x₂₀分别为2-乙酰基呋喃、柠檬烯、2-苯基乙醇二聚体、2-苯基乙醇单体、2-庚酮、E-2-辛烯醛、异丁酸），R₂=0.929，P＜0.05。另外，在贮藏过程中紧压白茶的特征挥发性物质间会相互作用，共同形成紧压白茶花香、清香药草味和坚果味的独特风味特征。运用GC-IMS技术、配合化学计量法能够科学辨别紧压白茶仓储年限，为规范紧压白茶市场提供理论依据。

Abstract:

In this study, 56 volatile compounds (VOCs) were identified from the pressed white tea in different years by gas chromatography-ion mobility spectrometry. Principal component analyses (PCA) and linear discriminant analysis(LDA) were used to screen 20 characteristic VOCs. The main VOCs were 2-acetylfuran, heptanal, E-2-octenal, limonene, 2-phenylethanol and isobutyric acid. The contents of limonene, 2-phenylethanol and isobutyric acid were in inverse proportion to the storage time, while the contents of 2-acetyl furan, heptanal and E-2-octenal showed positive correlation. The predictive model equations of storage time (y) and peak intensity response value of main VOCs were established by further regression analysis: y=-0.03x₁+0.038x₂-0.09x₃-0.012x₄+0.002x₅+0.004x₆+0.022x₇+0.019x₈-0.018x₉-0.011x₁₀+0.005x₁₁-0.011x₁₂+0.000x₁₃-0.042x₁₄-0.015x₁₅+0.017x₁₆+0.033x₁₇+0.008x₁₈+0.008x₁₉-0.124x₂₀ (x₁~x₁₃ were the unidentified VOCs, x₁₄~x₂₀ were 2-acetylfuran, limonene, 2-phenylethanol dimer, 2-phenylethanol monomer, 2-heptanone, e-2-octene aldehyde and isobutyric acid), R₂=0.929 and sig<0.05. In addition, the unique flavor characteristics of floral, aromatic herbs and nutty flavors in pressed white tea could be formed by the interaction between the characteristic VOCs of pressed white tea during storage. The storage life of pressed white tea could be scientifically distinguished by GC-IMS and stoichiometry, providing theoretical basis for standardizing the market of pressed white tea.