## 4 Discussion
pastorianus_ lie in the number (51 vs. 22) and the relative amounts of esters and phenols identified. These findings reflect the aromatic profile of the commercial strain, which likely lost the ability to produce a broad array of VCs due to a complex brewing domestication process. During this process, the fermentative capacity of the strain was prioritized over the production of complex aromatic profiles [35]. Esters were found in a higher proportion in the two yeast species analyzed in our study. These compounds are produced during the fermentation process and are usually characteristic of young beers [10]. Moreover, other compounds were identified, such as higher alcohols and phenols, of which the production is influenced by several factors, such as word composition, fermentation parameters, and beer maturation state [34]. The presence of these compounds, together with volatile-esters, is responsible for contributing to the final beer flavor [1; 8]. One of the most distinctive VCs produced by wild yeast is 4-VG [8]. The aroma and flavor descriptors used for this phenolic compound (identified in all _S. eubayanus_ stains) are wide-ranging, and include stable, barnyard, horsey, leather, smoky, spicy, clove, medicinal, and others ([PERSON] et al. 2017; [PERSON]. 2018), contributing significantly to the organoleptic profile. The role of phenols in the aromatic profile of the beer is questionable; in individual beer styles, such as Bavarian wheat beers and Belgian white beers ([PERSON] M. 2018), the phenolic flavors are desired and contribute to the style of the beer. However, the same VCs are perceived as undesirable in other fermented beverages and are commonly referred to as \"phenolic off-flavors\" (POF). Similar studies using other _S. eubayanus_ strains [36], indicated that this species produces higher levels of esters, phenols, and higher alcohols in fermentations at low temperatures (15 \({}^{\circ}\)C), compared to _Sp._W34/70. Indeed, our results followed the same trend, as we detected an additional set of VCs previously uncharacterized in lager beers. In this context, considering the great and novel diversity of VCs produced, the _S. eubayanus_ strains considered in our study show an innovative potential for alternative beer production. The volatile fraction of beer includes over 800 different compounds, but only several dozen of these are considered flavor active [37]. In this context, we selected compounds that could be relevant to discriminate the set of _S. eubayanus_ strains considered in our study and performed a PCA. When analyzing the distribution of the isolates, according to their aromatic profile, we observed a random distribution of the _S. eubayanus_ strains. There are no strains grouped by fermentation capacity or geographic isolation zone. By dividing the PCA into four quadrants (Q1-Q4), it is remarkable that strains with similar fermentative profiles are distributed in opposite quadrants. Given this, the quantity and variety of the VCs produced by _S. eubayanus_ isolates seem to be strain-specific traits, and reflect the great genetic diversity present in this species, as reported previously [19; 22]. In this context, the genetic diversity and the different VCs identified in _S. eubayanus_ resemble those described for _S. cerevisiae_, rather than _S. pastorianus_, likely determined by the genetic diversity of the species. _S. eubayanus_ is not the sole species to produce large amounts of volatile esters. For example, _S. cerevisiae_ strain Safale S-04 (Belgium) produces a wide range of these compounds, such as: ethyl acetate, isoamyl acetate, phenethyl acetate, ethyl decanoate, ethyl hexanoate, and ethyl octanoate [38; 39], responsible for giving the fermented word a fruity profile and in some cases a mixture with solvent aromas [7]. These profiles are attractive in the worldwide beer market, and the development of lager beers with fruity aromatic profiles fermented at low temperatures could likely be of interest in the global beer industry.