## 3 Results
### Extraction of Aromatic Compounds versus Type of Closure
In the case of the effect of the type of closure, ref. [18] described the presence of greater amounts of several ethyl esters in sparkling wine consumed using cork stoppers instead of micro-agglomerated stoppers. Diethyl succinate is regarded as a marker, primarily associated with the duration of cava storage in the cellar. This compound is defined as fruity or floral by tasters and is a marker of the evolution of sparkling wine because it is a post-ferentative volatile formed during the aging of sparkling wine in contact with lees from second fermentation [1,23]. Overall,diethyl succinate, TDN and hexanol seem to be compounds inherent in the bouquet of long-aged sparkling wines [24; 25]. The first two were detected in higher amounts in bottles with cork stoppers than screw-cap closures (Table A1, Appendix A). Finally, sparkling wine acetates like ethyl acetate decrease along the ageing time of sparkling wine in contact with lees [25]. However, a higher amount of this acetate was detected in products with screw-cap closures. In the case of cork closures, the second-most-abundant family of compounds was alcohols, which are related to yeast metabolism [1]. Sparkling wine alcohols such as isoamyl alcohol and phenylethyl alcohol were detected in bottles with both closures. The latter has influence on the sweet, rose and honey aroma structure of sparkling wines [26; 67; 68], and isoamyl alcohol can influence wine aroma by adding \"alcohol\" and \"nail polish\" notes [59]. Moreover, 1-hexanol was identified with both stoppers but in higher amounts with screw-cap closures. In the case of sparkling wines elaborated by traditional method, the alcohols augmented after alcoholic fermentation and remained almost constant after second fermentation and throughout aging. However, in the case of certain alcohols like 1-hexanol, they tended to increase, serving as a suitable ageing marker, as mentioned previously. Ref. [18] described that the levels of 1-hexanol were also significantly influenced by the type of closure in a sparkling wine. In accordance with these authors, the lower levels of 1-hexanol in sparkling wine sealed with cork stoppers may be due to its oxidation to 3-hexneal, but this aldehyde was not detected in the volatile composition of our samples under our experimental conditions. Additionally, 1-butanol was only obtained in screw-cap samples. According to [69], 1-hexanol contributes to the aroma of just-cut grass, and 1-butanol contributes to the medicinal aroma of wine. Concerning the acids, the most common were detected in both groups. However, the most representative, like octanoic and decanoic acid, have been detected in higher  
Figure 4: Percentages of major families of volatile compounds extracted by HP-SPME and TD (combined) in samples of sparkling wine with bottle aging after second fermentation using cork stoppers and screw cap. Cork stoppers are Cork 1 and Cork 2 samples. Screw cap is CC1, CC2, CC3 and CC4). The terpene family is not taken into account because they were detected in very low percentages. amounts in sparkling wines closured using screw caps. These acids, depending on the concentration, can have a negative role in the development of wine sensory profiles [26; 67]. Among ethers compounds, oxirane, 2-(1,1-dimethylethyl)-3-methyl- was identified in both groups of closures but was more abundant in screw-cap closures (Table A1, Appendix A). Furthermore, 1-Methyl-1-silacyclopentan-1-ol was only detected in screw-cap closures. Alkanes and ketones were determined in both closures, with results from cork stoppers being slightly higher than for screw caps. Aziridinylethylamine and hydroxyurea were presented only in screw-cap closures in higher amounts. This first is related to a fishy flavor [70]. Corlumine, N-Methylcalycotomine, phenol and emulphor were detected in screw-cap closures, while 12-O-Acetylingol 8-tiglate, 2-Myristynoyl pantetheine, 6,7-Dimethoxy-1,4-dimethyl-1,3-quinoxalinedithione and long-folenaldehyde were identified in cork stoppers.