# Pairing Red Wine and Closure: New Achievements from Short-to-Medium Storage Time Assays
## 3 Results and Discussion
### Volatile Profile of Wines Sealed with Different Types of Closures
#### 3.4.2 Burgenland Red Wine  
For the short storage assay with Burgenland red wines, a set of 161 volatile compounds was putatively identified, comprising a wide range of chemical families, including acids (10), alcohols (28), aldehydes (10), aromatic hydrocarbons (3), esters (44), ethers (3), furan derivatives (13), ketones (9), lactones (3), naphthalene compounds (4), norisoprenoids (2), phenol derivatives (7), sulfur compounds (5), terpenic compounds (13), and others (7). Within this data set, 119 (ca. 74%) exhibited significant differences between at least two wines bottled with different closures. A clustering analysis of the volatile patterns in Burgenland wines bottled with different closures was performed, with the heatmap and dendrogram representation revealing five main clusters (Figure 6a), showing that wines sealed with a screw cap seem to be more distinctive than others. Mixing was observed in the branches associated with wines sealed with micro-agglomerated cork stoppers from two producers. For analytes that showed statistically significant differences between at least two wines bottled with different closures, the average magnitude of variation was less than 0.25-fold. In this case, for a short storage period, clustering (with a similar Euclidean distance of 100) using all domains of information (sensory analysis, physicochemical parameters, phenolic compounds, and volatile organic compounds) revealed two main clusters: one comprising wines sealed with Natural Cork 2, Micro A, and Micro E, and the other comprising wine sealed with a screw cap (Figure 6b). This graphical representation highlights that the volatile composition is particularly sensitive to changes induced by closures, because when more domains of information are combined, there is less distinction between wines sealed with different closures (Figure 6b). Figure 6: Dendrogram and heatmap representation of Burgenland red wines sealed with Natural Cork 2, Micro A, Micro E, and screw cap closures: (**a**) the 161 volatile compounds identified in Supplementary Material Table S4, organized by chemical families separated by dashed lines; and (**b**) the combined domains of information, including sensorial analysis, physicochemical parameters, phenolic compounds, and volatile organic compounds. Euclidean distances are included on the dendrogram \(Y\)-axis. A chromatic scale (from dark blue, minimum, to dark red, maximum) was used for each variable, normalized by autoscaling. A detailed analysis of the volatile composition (Supplementary Material Table S4) revealed distinct patterns in the ester profile across wines sealed with different closures, once again highlighting the influence of stoppers on the volatile profile. These compounds, which are known to contribute to the floral and fruity notes in wine [15], were more abundant in the wine bottled with Natural Cork 2. This is evident from the slightly higher levels of ethyl octanoate (826.627 \(\pm\) 121.210 \(\mu\)g/L) and ethyl hexanoate (374.064 \(\pm\) 81.606 \(\mu\)g/L) in this wine compared to the other wines. Additionally, among the ethyl esters (Figure 7a), ethyl 2-phenylacetate also exhibited a slightly higher concentration in the wine sealed with Natural Cork 2 (16.910 \(\pm\) 2.894 \(\mu\)g/L). These data confirm that natural cork stoppers may contribute to the preservation of ethyl esters in red wines; the results for Douro wine are also considered. Attention was also devoted to Strecker aldehydes, which, as referred above, are compounds potentially associated with oxidative phenomena [69], including phenylacetaldehyde, 2-methylbutanal, and 3-methylbutanal (Figure 7b). Due to the high variability observed, namely for wine sealed with Natural Cork 2, the results obtained for this short storage in-bottle do not show noticeable differences associated with the closure type.