Analysis of Aroma Characteristics of Fermented Lingyun Baihao Tea Based on Odor Activity Value

Abstract

This study aimed to analyze the difference in aroma components and aroma characteristics of different types (white, oolong, yellow and black) of fermented Lingyun Baihao tea. The aroma components were identified by solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS), and odor activity value (OAV) was used to determine the key flavor components. By combined use of principal component analysis (PCA), orthogonal partial least square-discriminant analysis (OPLS-DA), cluster analysis and sensory evaluation, the aroma of fermented Lingyun baihao tea was comprehensively evaluated. The results showed that a total of 48 aroma compounds were identified in the tea samples, including 15 key flavor components and flavor-modifying components (OAV > 0.1). The cumulative interpretation rate R2X (cum) and the cumulative prediction rate Q2 (cum) of the PCA model were 0.984 and 0.846, respectively, and those of the OPLS-DA model were greater than 0.7 and 0.9, respectively. Both models had good fitness. The major differential components were linalool, isoamyl alcohol, 2-methylbutyraldehyde, β-ionone, nonanal and jasmone. The 15 aroma components were classified into three categories by hierarchical cluster analysis (HCA). Class I contained indole and dehydroalinalool, Class II contained linalool, nonanal, phenylacetaldehyde, hexanal, 2-methylbutyraldehyde, isovaleraldehyde, phenylethanol and isobutyraldehyde, and Class III contained jasmone, β-ionone, methyl salicylate, 2-pentylfuran and dimethyl sulfide. Class I was prominent in oolong tea samples, Class II was prominent in black tea samples, Class III was prominent in white tea samples, and Class II and III were prominent in yellow tea samples. These aroma characteristics were consistent with the results of sensory aroma evaluation. GC-MS analysis and OAV calculation combined with PCA, OPLS-DA and HCA can enable the identification and evaluation of Lingyun Baihao fermented tea aroma. The results of this study can provide a reference for the further development of Lingyun Baihao tea.

Keywords

• lingyun baihao tea; aroma components; odor activity value; fermented tea