# Characterization of the Aroma Profile of Commercial Prosecco Sparkling Wines
## Results and Discussion
### Sorting Task Analysis  
Wines were submitted to sorting task analysis in order to assess the existence of sensory groups based on their odor similarities. This approach has already been used to establish the existence of odor profiles associated with different variables, including grape variety, grape origin and yeast strain [10,13,43,48]. In this study, we were interested in verifying the existence of sensory groups attributable to the three different PDO appellations. The data obtained from the sorting task were entered into individual matrices for each judge, these matrices were aggregated in a single matrix and submitted to hierarchical cluster analysis (HCA). The results, shown in Figure 2, showed that the replicate wines were projected in the same cluster (sample no. 11), very close to each other, meaning that the panel was reproducible. The results showed that the Prosecco wines were divided into two groups of sensory similarity. The first group, (A), consisted of 11 wines, the second group, (B),  
Figure 1: Concentration of the sum of VSC and ethyl octanoate in wines from Asolo, Treviso and Valdobbiadene. of all other wines. The sensory groups were formed so that only part of the clustering could be attributed to the different PDOs. In fact, group A was almost entirely formed by Valdobbiane PDO and group B was formed by a mix of the three denominations with the exception of sample no. 1 which was derived, instead, from the DOC Treviso. These observations indicated that despite a strong segmentation according to different PDOs, a specific olfactory space did not exist for each of the two clusters. The volatile compounds characterizing the sensory clusters were then identified by means of Mann-Whitney test. Twenty-two volatile compounds showed significant differences (\(\alpha=0.1\)) across the two clusters (Table 5). Significant compounds were mostly terpenoids (8), VSC (4), esters acetate and ethyl esters (4), C\({}_{6}\)-alcohols (2), and one each of norisoprenoid, sesquiterpenoid, fatty acid and benzenoid. Cluster A was richer in esters such as isoamyl acetate, phenyl ethyl acetate and ethyl butanoate, that contributed to the fruity parameter, with acetates in cluster A showing about twice the content of cluster B. Cluster A was also richer in benzaldehyde and octanoic acid, with only octanoic acid largely exceeding the olfactory threshold and able to actively contribute to the aroma of the wines. Cluster B was richer in VSC, dimethyl sulfide, diethyl sulfide, dimethyl disulfide, and diethyl disulfide, all of which are characterized by the unpleasant aroma notes of onion, garlic, and sulfur. Moreover, cluster B showed a higher level of cyclic terpenoids such as cis-linaloid oxide, terpinene-1-ol, 1,4-cineole, p-cymene, and p-menthane-1,8-diols, and in the norisoprenoids, vitispirane; these compounds are characterized by odors of turpentine, resin, and camphor, which could have a negative impact--even if present at concentrations below the olfactory threshold--on the olfactory quality of cluster B wines. An average higher concentration of TDN was observed in cluster B, contributing to an aging aroma. A pleasant aroma that characterized cluster B was geraniol with its floral notes. Figure 2: Agglomerative hierarchical clustering of the sorting task scores; the numbers indicate Prosecco wine samples, the letters A and B indicate clusters. The dashed line indicates the significance threshold.