## 3 Results
### GC-MS Analysis
The proximity of groups B and A suggests that the flavor types were similar. The reliability of OPLS-DA was tested by performing 200 cross-replacement tests on the model, and the results are shown in Figure 4B. The horizontal coordinates in the graph are the retention of the samples, and the points at 1.0 are the R\({}^{2}\) and Q\({}^{2}\) of the original model. After validation, R\({}^{2}\) (0.101) and Q\({}^{2}\) (\(-\)0.735) were smaller than the retention value of 1.0, and the intercept of the model's Q\({}^{2}\) regression line with the horizontal coordinate was negative, which indicated that the model was free of overfitting and was stable and reliable. The variable projection importance factor (VIP) is commonly used for key variable analysis in OPLS-DA models. A VIP greater than 1 indicates a greater contribution [37]. The VIP values for each key component are shown in Figure 4C. Components with VIP values greater than 1 were hexanal, isovaleraldehyde, (E)-2-dodecenal, (E)-2-nonenal, (E)-2-dodecenal, (E)-2-ocenal, (E)-2-decenal, decanal, \(\beta\)-Myrcene, Limonene, and terpilene, which were identified as characteristic odor substances in combination with the OAVs and odor descriptions of key odor-activating substances. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**NO** & **Compound** & **Threshold** & **Odorant Description** & **CK** & **A** & **B** & **C** & **D** & **E** \\ \hline A1 & Hexanal & 4.5 & green onion flavor, green fruit flavor & - & 2.99 & 2.75 & - & 9.82 & 2.45 \\ A2 & Isovaleric aldehyde & 13 & apple, peach & 0.47 & 0.78 & - & 1.51 & 1.61 & - \\ A3 & Nomanal & 1 & green onion, green fruit flavor & 1.99 & 9.12 & 12.10 & 4.43 & 13.96 & 11.52 \\ A4 & (2E)-Dodecenal & 1.4 & citrus, fat & - & - & 1.35 & - & 0.05 & - \\ A5 & U-ecanal & 10 & oil, pungent, sweet & 0.04 & - & 0.14 & 0.09 & - & 0.83 \\ A6 & (2E)-Nonenal & 0.69 & cucumber, fat, green & - & 0.44 & 0.80 & 1.22 & 0.76 & 1.23 \\ A7 & (E)-2-Dodecenal & 1.4 & soap & - & - & 0.24 & - & - & 0.11 \\ A8 & Oct-2-enal & 0.3 & green, nut, fat & 2.25 & - & 1.49 & 1.42 & - & - \\ A9 & (2E)-2-Octenal & 3 & fat & - & 0.15 & - & - & 0.28 & 0.13 \\ A10 & (2E)-2-4-Decendienal & 2.3 & citrus, chicken & - & 0.10 & - & - & 0.18 & 0.79 \\ A11 & (E)-Decenal & 3 & soap & 0.06 & - & - & - & - & 0.47 \\ A12 & Decanal & 1 & soap, orange peel, tallow & - & - & - & 1.24 & - & 1.61 \\ A13 & Acetoin & 8 & butter, cream & 1.11 & 0.60 & 0.80 & 3.41 & - & 0.34 \\ A14 & Heptan-zone & 9 & pears & 0.37 & - & - & 0.18 & - & - \\ A15 & 2-Dudecanone & 7 & waxy, fruity, creamy, fatty, orris, floral & 0.41 & - & - & - & - & - \\ A16 & 2-Nonanone & 5 & green, weedy, earthy, herbal & 1.90 & - & - & 0.32 & - & - \\ A17 & 1-Octen-3-ol & 1 & mushroom & - & 6.90 & 5.55 & 7.02 & 7.17 & 3.80 \\ A18 & (E)-2-Octen-1-ol & 40 & mushroom & 0.13 & - & - & 0.04 & 0.05 & - \\ A19 & \(\beta\)-Myrcene & 13 & herb, wood, spice & 0.10 & - & - & 0.26 & - & - \\ A20 & Limonene & 4 & lemon, orange & 0.68 & - & - & - & - & - \\ A21 & D-Limonene & 60 & fruit & - & 0.56 & 0.48 & 1.71 & 0.40 & 0.09 \\ A22 & Terpilene & 85 & lemon, orange & 0.09 & 0.04 & - & 0.12 & - & - \\ A23 & \(\gamma\)-Decalactone & 2.6 & peach, fat & 0.71 & - & - & 0.18 & - & - \\ A24 & Estragole & 35 & licorice, arise & 0.89 & 0.34 & 0.54 & 0.49 & 0.25 & 0.14 \\ A25 & 2-pentyl-Furan & 6 & fruity, green & - & - & - & 0.27 & - & 0.23 \\ \hline \end{tabular} Note: CK: uncoxoked treated samples, A: boiled samples, B: steamed samples C: microwaved samples D: baked samples, E: air fired samples. odor descriptions were retrieved from [[https://www.thegoodscentscompany.com/search2.html](https://www.thegoodscentscompany.com/search2.html)]([https://www.thegoodscentscompany.com/search2.html](https://www.thegoodscentscompany.com/search2.html)), accessed on 18 July 2023.  
\end{table} 
Table 2: Odor thresholds and aroma-active compounds in different samples.