# Wild _Saccharomyces_ Produced Differential Aromas of Fermented Sauvignon Blanc Must
## 4 Discussion  
The molecular identification of yeasts permitted a reduction in the number of strains for assessment of fermentation experiments. The main barcodes for fungi, ITS and LSU regions, generally show low variability in the genus _Saccharomyces_, hindering the distinction of _S. cerevisiae_ from other species. Among nine strains previously identified as _Saccharomyces_ by sequencing the LSU and/or ITS regions, only three strains were not identified as _S. cerevisiae_ according to multiplex PCR using the specific primers ScerF2 and SceR2. Due to differences in the physiological tests, genetic profiles, and source of isolation, we suggest that strains 06 CE, 11 CE, and 33 CE are hybrids of _S. cerevisiae_ and other _Saccharomyces_ species. In fact, natural environments and industrial fermentations could have led to spontaneous formation of interspecific hybrids between _S. cerevisiae_, _S. kudriavzeii_, _S. uvarum_, and _S. euhyanus_[14; 36; 37]. These strains could be different in copy number, ploidy variations, genome rearrangements, and polymorphism changes [38]. After strain identification, the Intron Splice Site primer EI-1 was used to detect polymorphisms between the commercial yeast (SC2048) and wild strains 33 CE, 11 CE, and 06 CE, suggesting that they should be different to _S. cerevisiae_. However, we cannot confirm with our results that they were interspecific hybrids. The chemical composition of grapes strongly influences the formation of aroma compounds by _Saccharomyces_ species. In many cases, the yeast releases an aromatic compound from a nonvolatile precursor molecule. The genetic profile of _S. cerevisiae_ is relevant in the formation of metabolites that confer specific aromas after fermentation and, consequently, in wine. Moreover, several other factors also affect the spectrum of aroma compounds formed. Because of this, we characterized the unfermented SB must (Table 1) before fermenting it with the selected strains. C6 alcohols (1-hexanol, 2-hexanol, (_E_)-3-hexen-1-ol, and (_Z_)-3-hexen-1-ol) were present in the must, as a product of enzyme activity on linoleic and linoleic acids extracted from the grapes during the crushing stage. 1-Hexanol is one of the main compounds associated with the aroma of Sauvignon Blanc wines from Victoria, Australia, and Marlborough, New Zealand [39; 40]. Among the strains assessed in this study, the most notable was the strain 06 CE, whose production of 1-hexanol was identified as a positive contributor. Its presence is associated with nuances of herbal and resinous aromas, as well as the sensory characteristic of cut grass wine; therefore, it has been identified as an important compound [41]. The 12M strain showed concentrations of 1-propanol that can significantly influence the sensory properties of the wine. In fact, the fruity aroma at total concentrations below 300 mg/L of higher alcohols could contribute positively to the aromatic profile of wines, increasing fruity and flowery notes and aroma complexity. However, at levels above 400 mg/L, there should appear a negative effect caused by the apparition of pungent and unpleasant notes [42; 43]. Meanwhile, strain 01 PP was the major producer of both \(\beta\)-damascenone and \(\alpha\)-ionone, showing the highest intensity for red berry aromas, followed by floral aromas. Their sensory detection thresholds are 50 ng/L and 90 ng/L in hydroalcoholic solution, respectively, indicating their potential importance to wine flavor [44]. Wines of monoculture have much higher OAVs of fruity, floral, and sweety profiles, where _S. cerevisiae_ strains are protagonists due to the production of higher amounts of ethyl octanoate, ethyl decanoate, \(\beta\)-damascenone, and phenylacetaldehyde. In comparison, chemical, fatty, and herbaceous aroma series are equal in monoculture wines [45]. The accumulation of compounds in must is related to the anabolism of grape precursors, which stimulate the production of volatile compounds by yeast.