# Analysis of Floral Fragrance Components in Different Parts of _Iris typhifolia_
## 3 Results
\begin{tabular}{c} (E,\)-2, 6-dimethyl-2,4 \\ 23.19 \\ 23.19 \\ \end{tabular}  & \ \begin{tabular}{c} (E,\)-6-octritene \\ \end{tabular}  & \begin{tabular}{c} 0.22 \(\pm\) 0.1 d \\
0.93 \(\pm\) 0.59 d \\ \end{tabular}  & \begin{tabular}{c} (E,\)-6-octritene \\ \end{tabular}  \\ \hline \multicolumn{6}{c}{Note: The values in the table are the mean \(\pm\compounds in the pendant petal. Lastly, Cluster 4 shows the highest content of compounds in the flag petal [20]. Figure 8: The cluster analysis heatmap plot of volatile compounds in different parts of _Iris tyhifolia_. * The mass fractions of various volatile components were standardized in rows, meaning that each value is subtracted by the row mean and then divided by the row standard deviation. This standardization ensures that the resulting values are distributed between \([-1,1]\). The color gradient from blue to red indicates that the standardized values increase from smaller to larger magnitudes. The Odor Activity Value (OAV) is the primary criterion used to determine the overall contribution of volatile compounds to the aroma of a sample [21]. Based on previously reported aroma threshold values, the OAV values for different parts of _Iris tyhifolia_ were calculated. In total, 15 compounds were found to have OAV values greater than 1 in at least one part, including 7 aldehydes, 3 terpenes, 2 ketones, 1 alcohol, 1 ester, and 1 heterocyclic compound. These compounds significantly contribute to the aroma profile of the sample. The four parts can be divided into three categories based on the first-level clusterings. The flag petal is most similar to the pendant petal, and they are grouped together. In the second-level clustering, the stamens are grouped with two types of petals and are ultimately arranged alongside the pistil. From the heatmap, it is evident that there are significant differences in both the types and quantities of volatile compounds among the four parts. Moreover, in terms of the mass fraction, the pistil contains substantially higher levels of volatile compounds compared with the other parts. The clustering analysis results are consistent with those obtained from linear discriminant analysis (LDA), indicating a precise classification of aroma compounds among the different parts of _Iris tyhifolia_. Additionally, the pistil is regarded as the primary contributor to the types and amounts of the volatile compounds in _Iris tyhifolia_. The odor activity values, concentration thresholds, and aroma descriptors for the four parts of _Iris tyhifolia_ can be found in Table 3. In the stamen, a total of 10 characteristic aroma substances were detected and quantified. Among them, linalool, nonyl aldehyde, and capric aldehyde had relatively high OAV values, giving the fragrances of lilac, fat, and sweet orange, respectively. These compounds also constitute the main aromatic substances in the flag petal, which includes five characteristic aroma compounds. In the pistil, a total of eight characteristic aroma substances were detected and quantified. Notably, 2-methoxy-3-sec-butylpyrazine and caproaldehyde had exceptionally high OAV values, providing the aromas of fresh legumes and fruits, respectively. These two substances showed the highest OAV values among all the aroma components in the different parts, emphasizing the significant contribution of pistils to the overall aroma profile. In the pendant petal, a total of nine characteristic aroma substances were detected and quantified. Among them, 2-hexenal and methyl heptenone were unique to this part, giving the aromas of leaves and lemongrass, respectively. Additionally, 2-methoxy-3-sec-butylpyrazine and trans-2-hexenal had relatively high OAV values, and the latter primarily contributed to the apple-like aroma. Among the characteristic aromatic compounds detected above, 2-hexenal can be utilized in food additives and organic synthesis intermediates [22]. 2-methoxy-3-sec-butylpyrazine exhibits physiological or pharmacological activity and can serve as a sensory