## 3 Results and Discussion
### Free-Form Compounds  
#### 3.1.1 Aldehydes  
The concentration of all aldehyde compounds was higher in fresh grapes, except (E,E)-2,4-nonadienal, (E)-2-heptanal, and benzaldehyde. The compounds (E)-2-nonenal and (E,E)-2,4-heptadienal came from the oxidation of linoleic acid [30], and decanal produced by the oxidation of oleic acid [31] were not identified in fresh grapes (Table 1). The content of VOCs was comparatively higher in fresh grapes as compared to all raisins, which were prepared in different ways. Among raisins, the SD and PSD treatments were produced in higher concentrations than AD and PAD, excluding (E)-2-heptanal and phenylacetaldehyde (Table 1). The higher content in SD and PSD is might be due to the intense light with high temperature [3,5]. Figure 1: The concentration of free- and glycosidically bound-form compounds in different classes of centennial seedless. \begin{table} \begin{tabular}{c c c c c c c c c c c} \hline
**S.N** & **RI** & **Compound Name** & **Ion m/\(\mu\)z** & **ID** & **Source** & **Fresh** & **AD-Rain** & **PAD-Rain** & **SD-Rain** & **PSD-Rain** \\ \hline  & & & & & & & & & & & \\  & & & & & & & & & & & \\  & & & & & & & & & & & \\
1 & 975 & Pentanal WJ & 44 & 2 & UFAO & 167.92\(\pm\) 13.06a & 69.36\(\pm\) 2.34 cd & 64.23 \(\pm\) 2.51d & 86.8 \(\pm\) 6.14 bc & 81.01 \(\pm\) 7.6 db & \\
2 & 1066 & Hexanal WJ & 44 & 1 & UFAO & 6972.2\(\pm\) 365.7a & 365.44 \(\pm\) 24.86b & 285.95 \(\pm\) 2.99b & 547.62 \(\pm\) 13.12b & 551.07 \(\pm\) 5.42b \\
3 & 1178 & Hepanal WJ & 44 & 2 & UFAO & 86.11 \(\pm\) 7.32a & 34.22 \(\pm\) 0.87 bc & 24.76 \(\pm\) 1.43c & 48.17 \(\pm\) 3.71b & 36.66 \(\pm\) 0.7 bc \\
4 & 1292 & Octanal WJ & 43 & 2 & UFAO & 386.85 \(\pm\) 45.07a & NE & NF & NF & NF \\
5 & 1393 & Nomanal WJ & 57 & 1 & UFAO & 6.38 \(\pm\) 0.08a & 1.18 \(\pm\) 0.23c & 1.38 \(\pm\) 0.07 bc & 1.74 \(\pm\) 0.35b & 1.49 \(\pm\) 0.27c \\
6 & 1501 & Decanal WJ & 43 & 1 & UFAO & NE & NF & 1.88 \(\pm\) 0.07a & 1.84 \(\pm\) 0.07a & 2.08 \(\pm\) 0.04a \\
7 & 1217 & (_E_)-2-Hequal WJ & 41 & 1 & UFAO & 3004.21 \(\pm\) 85.48a & 637 \(\pm\) 3.77c & 134.68 \(\pm\) 9.12b & 17.77 \(\pm\) 0.32c & 44.97 \(\pm\) 2.29c \\
8 & 1325 & (_E_)-2-Heppanal WJ & 41 & 2 & UFAO & 27.41 \(\pm\) 22c & 111.29 \(\pm\) 6.05a & 18.41 \(\pm\) 0.37c & 57.83 \(\pm\) 9.67b & 24.88 \(\pm\) 3.14c \\
9 & 1434 & (_E_)-2-Decanal WJ & 41 & 2 & UFAO & 27.27 \(\pm\) 5.67a & 6.69 \(\pm\) 14.41d & 4.68 \(\pm\) 0.16e & 113.39 \(\pm\) 0.38e \\
10 & 1539 & (_E_)-2-Nomanal WJ & 43 & 2 & UFAO & NE & NF & 2.5 \(\pm\) 0.1p & 7.44 \(\pm\) 0.38a & NE \\
11 & 1497 & (_E_)-2-Heppanal WJ & 81 & 2 & UFAO & NE & NF & 86.17 \(\pm\) 4.17b & 111.88 \(\pm\) 7.03a \\
12 & 1705 & (_E_)-2-Nomanal WJ & 81 & 2 & UFAO & 179.65 \(\pm\) 3.2b & 241.35 \(\pm\) 13.59a & 95.46 \(\pm\) 8c & 106.78 \(\pm\) 12.96c & 94.33 \(\pm\) 4.12c \\
13 & 1530 & Benzaldehyde WJ & 77 & 1 & MR & 13.43 \(\pm\) 0.13b & 25.6 \(\pm\) 1.57a & 15.2 \(\pm\) 0.66b & 14.1 \(\pm\) 1.75b & 14.05 \(\pm\) 1.46b \\
14 & 1650 & Prehyacetaldehyde WJ & 91 & 1 & MR & 386.96 \(\pm\) 11.48a & 326.67 \(\pm\) 21.3b & 164.34 \(\pm\) 2.331c & 141.21 \(\pm\) 11.87d & 101.89 \(\pm\) 9.17e \\ \hline  & & & & & & & & & & \\ \end{tabular}