# Effects of Long-Term Bottle Storage on Red and Rose Wines Sealed with Different Types of Closures
## 4 Discussion  
For the first time, South Tyrolean wines (three red and one rose) stored for thirty months in bottles and sealed with different types of closures were studied in terms of changes in volatile and phenolic compounds and their content of free and total sulfites and dissolved oxygen. The concept of this work was not the absolute quantification of volatile compounds and phenols in these red and rose wines, but to investigate if storage with different closures could have an impact on the chemical composition of wines. For this purpose, an absolute quantification is not necessary; in fact, ANOVA and multivariate statistical models such as PCA are based on relative abundances (and their variance), and not on an absolute quantification. One-way ANOVA was considered the best approach for this study, as the \"blend\" closure was compared for each wine with a conventional closure analyzed after a prolonged storage of the wines in bottles. The closure type (blend _vs_ conventional) did not significantly affect (\(\alpha<0.01\)) free or total SO\({}_{2}\) or the dissolved oxygen content of any of the wines, with the exception of the free SO\({}_{2}\) content of Lagrein rose. This means that, in general terms, all the different types of corks examined mostly ensured good hermeticity during the first 30 months of storage in bottles. In particular, this is important for the winemaker, whose first concern is to maintain the levels of free (and total) sulfites present at bottling, in order to ensure the protection of the wine from oxidation and abnormal fermentations. In the case examined, it was not found that there was a systematic difference in the content of free sulfites in any of the wines according to the type of cork used. As the differences in free and total sulfite and dissolved oxygen content among the corks used were almost never significant, it is not straightforward to describe the mechanisms that can be predicted from the chemical data here--particularly the influence of oxygen transfer through the cork on various phenolic compounds, sulfur dioxide, and volatiles. After thirty months of storage, without taking into account the effect of the type of closure, many volatile compounds with a number of carbon atoms from 7 to 18, including long-chain ethyl esters, disappeared, while some esters appeared--probably due to the condensation of higher alcohols (e.g., isoamyl alcohol) with organic acids formed after fermentation. In addition, some higher alcohols and C7 and C8 aldehydes disappeared--probably due to oxidation. A significant difference in the volatile profiles was observed only in Lagrein red wine closed with the 'conventional' closure, which showed a higher content of 2, 3-butanediol and ethyl octanoate compared to the 'blend' cork after 30 months. Octanoic acid and diethyl succinate (fermentative volatile compounds) contributed to distinguishing the Merlot samples, which showed the highest dissolved oxygen content. Regarding the \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Merlot** & **Lagrein Red** & **Lagrein Rosé** & **St. Magdalener** \\ \hline ns & ns & * & * \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Triangle test. ns: not significant; * significant (\(\alpha<0.05\)). differences in phenolic content induced by the closure used, GRP and (\(-\))-epicatechin were the compounds that most consistently changed in the wines. In general, the cinnamic acids, flavanols, and phenolic acids were the most affected by the closure, while anthocyanins differentiated by the closure used only in the St. Magdalener wines. In our case, when the differences were indeed significant, conventional closure-closed wines generally showed higher relative abundances of epicatechin in three of the four wines and lower relative abundances of GRP (in all the three red wines) and other phenolic acids, such as syrginic and protocatechuric acids. Finally, anthocyanins and caffe acid were significantly higher in the St. Magdalener wines closed with conventional closures. [PERSON] et al.