## 3 Results and Discussion
### The Composition and Changes of VOCs in the Ripening Process of _R. roxburghii_ Fruit  
VOCs play a crucial role in assessing fruit aroma and significantly influence consumer acceptance. A total of 145 VOCs were identified in _R. roxburghii_ across five different ripening stages using HS-SPME-GC-MS (Table 1). The identified compounds were categorized as follows: 19 aldehydes, 17 alcohols, 30 esters, three acids, 14 ketones, 44 alkenes, nine alkanes, four phenols, and five other compounds. Notably, the VOCs present in _R. roxburghii_ exhibited differences in composition and content across the various ripening stages. Importantly, six compounds (four aldehydes, one alcohol, and one ester) were consistently present at all five ripening stages: 2-(E)-hexenal, 1-nonanal, (E)-2-pentenal, hexanal, 1-hexanol and hexyl acetate. These findings are comparable to the principal volatiles identified during the maturation of peach [41] and kiwifruit [42]. Similar substances are primarily C\({}_{6}\) volatile compounds, likely due to the fact that these compounds, commonly found in fresh fruits, are produced mainly through the action of lipoxygenase on C\({}_{18}\) unsaturated fatty acids, such as linoleic acid and linoleic acid [43]. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**Compounds**} & \multirow{2}{*}{**RT**} & \multirow{2}{*}{**RI**} & \multirow{2}{*}{**LRI**} & \multicolumn{6}{c}{**Relative Content (mg/kg)**} \\ \cline{5-10}  & & & & & & **I** & **II** & **III** & **IV** & **V** \\ \hline
1 & (E)-2-Pentenal & 9.582 & 744 & ND & 4.34 & 2.20 & 2.80 & 4.02 & 8.32 \\
2 & Hexanal & 10.962 & 801 & 806.1 & 81.13 & 43.26 & 49.14 & 177.11 & 66.54 \\
3 & 2-(E)-Hexenal & 12.733 & 847 & 861.7 & 55.46 & 21.12 & 19.45 & 209.15 & 18.37 \\
4 & (E,E)-2,4-Hexadienal & 14.399 & 931 & 921.4 & 4.58 & ND & ND & ND & ND \\
5 & (Z)-2-Heptenal & 15.389 & ND & 960.5 & ND & ND & ND & ND & 1.95 \\
7 & (E)-2-Heptenal & 15.57 & 978 & 967.6 & 16.54 & 9.86 & 11.28 & 9.46 & ND \\
6 & Benzaldehyde & 15.751 & 961 & 968.4 & 1.48 & 0.09 & ND & 0.60 & 2.26 \\
8 & Octanal & 16.494 & 1002 & 1005.0 & ND & ND & 20.81 & 9.97 & 57.75 \\
9 & Cyanamide, N- & & & & & & & & \\
10 & (E)-2-Octenal & 17.76 & ND & 1066.3 & ND & ND & 4.82 & ND & ND \\
11 & 2-Isopropyl-5-methylhex-4-enal & 17.846 & 1064 & 1070.5 & 5.59 & ND & 4.72 & 0.93 & ND \\
12 & 1-Nonanal & 18.255 & ND & 1090.3 & 0.33 & ND & ND & ND & ND \\
13 & 1-Nonanal & 18.598 & 1105 & 1115.6 & 13.18 & 19.31 & 77.19 & 56.64 & 102.94 \\
13 & 1-Fenna 3766 & 19.712 & 1162 & 1168.7 & 0.50 & ND & ND & ND & ND \\
14 & (E)-2-Nonanal & 19.816 & 1164 & 1174.4 & 0.74 & 0.39 & 0.91 & ND & ND \\
15 & Decyl aldehyde & 20.645 & 1204 & 1218.8 & 2.33 & 2.26 & 4.04 & ND & ND \\
16 & \(\beta\)-Cyclocitral & 21.178 & 1222 & 1244.7 & 0.66 & ND & ND & 1.74 & ND \\
17 & (E)-Citral & 21.911 & 1269 & 1285.0 & ND & 0.12 & 0.57 & ND & ND \\
18 & 2-Undecenal & 23.853 & 1359 & 1378.2 & 1.90 & 1.10 & 1.63 & ND & ND \\
19 & Fema 3082 & 23.91 & ND & 1378.2 & 0.27 & 0.30 & 1.11 & ND & ND \\ Aldehydes (19) & & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: HS-SPME-GC-MS analysis results of VOCs in _R. roxburghii_ fruit at different ripening stages.