# 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
Figure 7: Boxplots of concentrations of (**a**) ethyl esters (ethyl octanoate and ethyl 2-phenylacetate), (**b**) Strecker aldehydes (phenylacetaldehyde, 2-methylbutanal, and 3-methylbutanal), (**c**) norisoprenoids (safranal and \(\beta\)-damascenone), (**d**) terpenic compounds (rose oxide, nerol oxide, and camphor), (**e**) sulfur compounds (methylthioacetate, 2-thiophenecarboxaldehyde, dimethyl disulfide, 2-methyl-3-thiolanone, and 3-(methylthio)-1-propanol) determined in Burgenland red wine bottled with Natural Cork 2, Micro A, Micro E and screw cap closures. The results expressed in equivalents of 3-octanol (internal standard). Different superscript lowercase letters in a row represent statistically significant differences between wines bottled with different closures at \(p<0.05\), using multiple \(t\)-tests and GraphPad prism. These compounds were selected due to their relevance to wine’s aroma and their role in oxidative and reductive processes, allowing for a comprehensive evaluation of how closure type influences wine composition. Two norisoprenoids, safranal, and \(\beta\)-damascenone, were detected in all the studied Burgenland red wines (Figure 7c). For this short storage time in the bottle, differences among the wines sealed with different closures are not so clear. Statistically significant differences were only observed for \(\beta\)-damascenone, with the wine sealed with Micro A showing a slightly higher concentration (1.213 \(\pm\) 0.099 \(\upmu\)g/L) compared to the wine sealed with screw cap (1.058 \(\pm\) 0.061 \(\upmu\)g/L), despite both compounds being present at low levels overall. For the terpene compounds, with the exception of camphor, the difference in the terpene profile between wines sealed with different closures is not particularly noticeable (Figure 7d). Despite this, the wines sealed with Natural Cork 2 exhibited a high variability among bottles (Figure 6a); in general, they exhibited the highest total content of terpene compounds (31.251 \(\pm\) 3.083 \(\upmu\)g/L), while the total terpene content of the wines sealed with the other closures ranged between ca. 20.972 and 27.931 \(\upmu\)g/L (Supplementary Material Table S4). As observed from the Douro assay, camphor was identified exclusively in the wine sealed with Natural Cork 2, reinforcing the claim that this compound was released into the wine via natural cork stoppers [12]. Although no significant differences were observed for rose oxide among the terpene oxide types, nerol oxide demonstrated a slight statistically significant difference between the wine bottled with Natural Cork 2 (5.395 \(\pm\) 0.637 \(\upmu\)g/L) and the wine bottled with Micro E (4.768 \(\pm\) 0.275 \(\upmu\)g/L), showcasing potential variations that may arise as a result of the closure type. Sulfur compounds represent another group of volatile molecules worth noting, as they are reduction-driven volatiles present in the sample. While some sulfur compounds contribute positively to the wine's aroma profile, others are associated with reductive aromas, often perceived as sensory defaults [17]. Five sulfur compounds were identified in this study: methylthioacetate, 2-thiophenecarboxaldehyde, dimethyl disulfide, 2-methyl-3-thiolanone, and 3-(methylthio)-1-propanol (also known as methionol), all of which exhibited slightly higher concentrations in wines sealed with a screw cap (Figure 7e). The greater concentrations of these sulfur compounds in wines sealed with screw caps may indicate a more pronounced reductive environment. The increased presence of methionol (8.697 \(\pm\) 0.957 \(\upmu\)g/L), for example, is often associated with off-flavors such as potato, soup, or cooked cabbage [70], which could be perceived as undesirable in wines with excessive reductive aromas.