## 3 Results and Discussion
### Volatile Compound Composition
#### 3.1.1 Alcohols  
Alcohols are the major volatile compounds that are yielded during wine fermentation. C\({}_{6}\) and higher alcohols detected in these wine samples represented about 43% to 73% of the total volatile content, indicating that these volatiles played a significant role in the determination of the overall aroma of these wines. After fermentation, there were five C\({}_{6}\) alcohols detected in these wine samples, and the clone 169 wine after fermentation exhibited higher total C\({}_{6}\) alcohols content. Additionally, the individual C\({}_{6}\) alcohols, including 1-hexanol, (\(E\))-3-hexen-1-ol, and (\(Z\))-3-hexen-1-ol, were observed to be significantly (\(p\leq 0.05\)) higher in the clone 169 wine except for (\(Z\))-2-hexen-1-ol (Table 2). During the aging process, a decrease on these C\({}_{6}\) alcohols happened in both clone wines (Figure 1a). (\(E\))-2-Hexen-1-ol, 1-hexanol, (\(E\))-3-hexen-1-ol, and (\(Z\))-3-hexen-1-ol decreased their content in these wines by 45-52%, 10-12%, 14-22%, and 9-22%, respectively (Table 2). After 12-month aging, the differences in individual C\({}_{6}\) alcohols between the two clone wines remained unchanged (Table 2).  
The clone 169 wine also displayed higher total higher alcohols content compared with the clone 191 wine before the oak barrel aging (Table 2). Most of the individual higher alcohols were present at higher levels in the clone 169 wine than in the clone 191 wine before aging. Clone 169 wine contained significantly (\(p\leq 0.05\)) higher concentrations of 1-pentanol, 1-butanol, 3-methyl-1-pentanol, 2-phenylethanol, and isopentanol. 1-Octen-3-ol exhibited significantly (\(p\leq 0.05\)) higher levels in the clone 191 wine before the aging process. It has been reported that amino acids in grapes can be metabolized during the wine making process to yield higher alcohols [42]. Therefore, the impact of clonal differences on the higher alcohols levels in these wines before aging might be mainly due to the difference in amino acid composition between these grape clones. Most of the higher alcohols, such as isopentanol, 4-methyl-1-pentanol, 3-methyl-1-pentanol, 1-octanol, and 1-decanol, exhibited a dramatic decrease between 0 and 3 months of the aging process (Figure 1a). Afterwards, the content of these higher alcohols in the wines remained constant or slightly increased until the end of the aging. During the aging period, the concentrations of 1-octanol, 1-decanol, 4-methyl-1-pentanol, and 3-methyl-1-pentanol decreased by 67-70%, 30-40%, 17-21%, and 15-19%, respectively (Table 2). On the contrary, the concentrations of 1-pentanol, 1-octen-3-ol, 2-nonanol, and 1-dodecanol increased by 14-38%, 10-29%, 37-50%, and 48-108%, respectively (Table 2). It has been reported that esters in wine can be hydrolyzed into higher alcohols during the aging process [9]. We speculated that the accumulation of these higher alcohols in the wines during the aging process might result from the hydrolysis of their corresponding esters. At the end of the aging period, the wine made from clone 169 showed significantly (\(p\leq 0.05\)) higher content of nine higher alcohols. Regarding these higher alcohols, 1-butanol, 1-pentanol, isopentanol, and 3-methyl-1-pentanol showed higher content in the clone 169 wine before and after the aging process, whereas 3-octanol, 1-decanol, 4-methyl-1-pentanol, and benzyl alcohol were present in a higher content in the clone 169 wine after 12 months of aging. It should be noted that the aging process reduced the content of isobutanol, 2-phenylethanol, and 1-octen-3-ol in the clone 169 wine, making the contents of these higher alcohols similar in both clone wines. The benzyl alcohol content was significantly (\(p\leq 0.05\)) higher in the wine aged in the Bordeaux oak barrel than that aged in the Wolin oak barrel after the aging process (Table 2).