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.
