## 3 Results and Discussion
### Multivariate Statistical Analysis
#### 3.4.2 rOAV Analysis of Differential Volatile Components  
Not all volatile components in tea contribute to the aroma quality. Therefore, in this study, the relative odor activity value (rOAV) was calculated to evaluate the specific contributions of the abovementioned differential volatile components to the aroma of Rucheng Baimao black tea in different seasons. Generally, a volatile component with rOAV > 1 is considered to make an important contribution to the aroma quality [59]. By referring to the literature and databases, the odor thresholds of the differential volatile components were obtained and the rOAV values were calculated. The results are shown in Table 3. Among the 34 differential volatile components, the thresholds of 24 components were available for rOAV calculation. The rOAV values of 11 differential volatile components were greater than 1, including geraniol, linalool, methyl salicate, nonanal, phenylacetaldehyde, benzaldehyde, phenethyl alcohol, benzyl alcohol, \(\beta\)-ionone, _trans_-nerolidol, and (\(E\))-citral. Most of these volatile components exhibit floral, fruity, sweet, and fresh scents, jointly forming the aroma quality characteristics of Rucheng Baimao black tea. The rOAV values of phenethyl alcohol and \(\beta\)-ionone both exceeded 200, indicating that they may play an extremely important role in the formation of the floral aroma quality of Rucheng Baimao black tea. In addition, the aroma quality of tea is the result of the combined effect of volatile components in tea at different concentrations on the human olfactory nerve [60]. Therefore, volatile components with rOAV < 1 also contribute to the aroma quality of tea. Among the differential volatile components, the rOAV values of hotrienol, \(\alpha\)-farnesene, 2-heptanol, (\(E\))-linalool oxide (pyranoid), and 2-hexenal were between 0.1 and 1, suggesting that they may modify the aroma quality of Rucheng Baimao black tea. The rOAV values of caffeine, tetradaceane, (\(E\))-linalool oxide (furanoid), jasmine lactone, 5-methyl-2-hexanol, benzyl nitrile, and 2.6-di-tert-butyl-4-methylphenol were less than 0.1, which may have potential effects on the aroma quality of Rucheng Baimao black tea [59].  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Volatile Components**} & \multirow{2}{*}{**Thresholds (\(\mu\)g/kg)**} & \multicolumn{3}{c}{**rOAV**} \\ \cline{3-5}  & & **SPBT** & **SUBBT** & **AUBT** \\ \hline Geraniol & 1 & 66.34 \(\pm\) 8.50 & 10.25 \(\pm\) 0.36 & 9.99 \(\pm\) 0.71 \\ Linalool & 6 & 3.08 \(\pm\) 0.43 & 8.64 \(\pm\) 0.68 & 5.37 \(\pm\) 0.13 \\ Hotrienol & 110 & - & - & 0.10 \(\pm\) 0.00 \\ Methyl salicate & 16 & 1.65 \(\pm\) 0.26 & 1.30 \(\pm\) 0.08 & 0.87 \(\pm\) 0.04 \\ \(\alpha\)-Farnesene & 87 & - & - & 0.10 \(\pm\) 0.01 \\ Nonanal & 1 & 10.63 \(\pm\) 0.94 & - & - \\ Quinuclidine & - & - & - & - \\ (\(E\))-Geranic acid & - & - & - & - \\ Caffeine & 2000 & \textless{}0.1 & \textless{}0.1 & \textless{}0.1 \\ Phenylacetaldehyde & 0.3 & 11.09 \(\pm\) 1.07 & 42.87 \(\pm\) 5.68 & 17.30 \(\pm\) 1.30 \\ Benzaldehyde & 3 & 0.85 \(\pm\) 0.16 & 3.56 \(\pm\) 0.54 & 1.15 \(\pm\) 0.02 \\ Methyl ggeranoate & - & - & - & - \\ Phenethyl alcohol & 0.015 & 469.02 \(\pm\) 74.84 & 781.15 \(\pm\) 98.84 & 343.60 \(\pm\) 29.48 \\ Tetradecane & 1000 & \textless{}0.1 & \textless{}0.1 & \textless{}0.1 \\
2-Heptanol & 13 & - & 0.45 \(\pm\) 0.02 & - \\ Benzyl alcohol & 2.54 & 1.46 \(\pm\) 0.27 & 3.25 \(\pm\) 0.50 & 0.90 \(\pm\) 0.14 \\ (\(Z\))-6-Methyl-2-undecene & - & - & - & - \\ (\(E\))-Linalool oxide (furanoid) & 320 & \textless{}0.1 & \textless{}0.1 & \textless{}0.1 \\
4,6,8-Trimethyl-1-nonene & - & - & - & - \\ (\(E\))-Linalool oxide (pyranoid) & 50 & \textless{}0.1 & \textless{}0.1 & 0.11 \(\pm\) 0.01 \\ \hline \hline \end{tabular}
\end{table}
Table 3: ROAV analysis of differential volatile components in Rucheng Baimao black tea across different seasons.