## 3 Results
### Extraction of Aromatic Compounds versus Type of Closure
Alcohols were the second-most-abundant family, with the highest levels of isoamyl alcohol in the case of TD extraction and phenylethyl alcohol in the case of HP-SPME. According to [59], phenylethyl alcohol contributes to the sweet, floral, and honey-like aroma profile of sparkling wines. Both higher alcohols have already been identified in sparkling wines [59]. Other representative alcohols such as 1-hexanol and 1-butanol, which are mostly produced during the pre-fermentation wine production process, were extracted using TD. Also, 1-hexanol is a representative alcohol characterized by \"green\" and \"herbaceous\" notes. The different origins of the grapes and/or the winemaking conditions used are likely linked to the presence of fatty acids [60]. The most significant acids identified were different depending on the use of TD or HP-SPME. Octanoic and decanoic acid were obtained by both methods, but the highest percentage of area was detected in the sparkling wines analyzed by HP-SPME (Table 11, Appendix A). We found that some compounds such as succinic acid and dimethyl caffeic acid were only detected by HP-SPME, and others like alkynyl stearic acid, 3-hydroxydodecanoic acid, acetic acid or aminometanesulfonic acid were identified using TD. In the case of ether compounds, 2-(1,1-dimethylethyl)-3-methyloxirane and 1-Methyl-1-silacyclopentan-1-ol were identified. The latter was only detected using TD. Ethers are a type of volatile compound that significantly contribute to the intricate aroma of wine. They are mainly produced throughout the alcoholic fermentation, but additionally, they can also develop during the wine-aging process as the wine undergoes chemical reactions in barrels or bottles [61]. Although ethers are less prevalent than esters, their presence enhances the wine's aromatic complexity, offering scents that span from herbaceous to floral and spicy. Their interaction with other volatile and non-volatile elements in the wine further shapes their sensory perception and overall impact. Ketones are a key group of volatile compounds that play a significant role in shaping the aroma profile of wine. Their presence has a crucial impact in the complexity of wine's sensory attributes, although its concentration is lower compared to other volatiles like esters and alcohols. Ketones are primarily formed during the fermentation processes but also in the aging step [62]. HP-SPME was the best method used to extract alpha-ionone or a C13-norisoprenoid that is known for its contribution to the aroma of fruits. Other ketones such as caprolactone or 2,3,4,5,6,6-hexamethylcyclohex-2,4-dien-1-one were also detected using HP-SPME. On the contrary, 2,2-dimethyl-5-phenylfuran-3-one was extracted using TD. Lactones were also detected in sparkling wines due to the aging process because they are generated by the hydrolysis of the precursors. Alkanes are naturally present in the waxy cuticle of grape skins. They can also form during the fermentation process, because yeast metabolism can produce them as secondary metabolites, or during the aging of wine, due to chemical reactions that can generate or modify alkane compounds. The number and nature of extracted alkanes depend on the extraction methodology. Levels of pentacosane, nonacosane, tetratriacontane, hexatriacontane, 3-choropentane and vinyl decanoate were obtained using HP-SPME. On the other hand, n-hexane, octathioacane, 5-methyl-hexadecane, hexadecane and octadecane were extracted by the TD method. Alkanes typically have a relatively low impact on the aroma profile of wine due to their low volatility. However, they can contribute to the background complexity and texture of the wine. Terpene compounds, which are a major group of wine aroma compounds known for their floral aromas, were similarly identified using both HP-SPME and TD techniques. It seems that these groups of compounds are produced during the pressing of grapes and the settling process. Squalene is a natural triterpene widely distributed in nature, and it was extracted using both methodologies.