# Evaluation of Probiotic _Saccharomyces boulardii_ Yeast as a Distillery Strain
## 3 Results and Discussion
### HPLC Analysis of Fermented Media
#### 3.2.4 Results of GC Analysis of Molasses Worts and Rye Mashes After Fermentation
Analysing the effect of extract content on the concentration of higher alcohols and carbonyl compounds, it can be concluded that only in the case of acetal diethyl acetaldehyde did this parameter have a similar effect during the fermentation of molasses words by all yeast strains tested. Indeed, acetal concentration was higher in words with an initial extract of 17% (\(w/w\)). Regarding the other compounds, only in the case of some yeast strains did their concentrations differ depending on the extract content. This was the case with SB yeast, as the concentrations of compounds such as 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-phenylethanol, isobutyric aldehyde, and diacetyl were lower in words with an initial extract content of 10% (\(w/w\)) compared to their concentrations in words with a higher extract of 17% (\(w/w\)). As the extract increased, the concentration of substrates used in yeast metabolic processes during ethanol fermentation, including sugars and amino acids, increased. This may have resulted in increased production of volatile compounds, but this is an individual yeast strain characteristic. The response to a higher extract is a higher ethanol concentration, and this may translate into an increase in ethyl esters, which was confirmed in words fermented by SB and TD yeasts. [PERSON] et al. [42], investigating the effect of sugar concentration on the composition of mango wine, showed that fermentation of a substrate with a higher sugar content increased the concentration of isoamyl acetate, reasoning that this may have been influenced by the higher concentration of isoamyl alcohol. In our study, no such relationship was found for both isoamyl acetate and 2-methylbutyl acetate and 2-phenylethyl acetate since in words (17% \(w/w\)) with higher concentrations of higher alcohols--the precursors of these esters--their concentrations were lower compared to the composition of words with a lower extraction (10% \(w/w\)). In contrast to the results from the fermentation of molasses words, the analysis of variance of the results obtained after fermentation of rye mash (Table 8) showed a significant effect of the extract on the concentration of higher alcohols, including those most critical in terms of quantity, i.e., isobutyl alcohol, isoamyl alcohol, amyl alcohol, amyl alcohol, and 2-phenylethanol. Indeed, higher concentrations of the above alcohols were determined in the higher-extract mash for all three tested yeast strains. Rye grains are rich in amino acids--precursors for the synthesis of higher alcohols in the pathway proposed by [PERSON] [43] in which the deamination of amino acids and decarboxylation of the resulting \(\alpha\)-keto acids produce the corresponding aldehydes, which in turn are reduced to the appropriate alcohols. Compared to molasses worts, the proportion of amyl alcohols in the total sum of higher alcohols was lower, ranging from 45.40 to 52.24% and decreasing in favour of 2-phenylethanol, whose proportion was higher, ranging from 33.29 to 44.27%. A consequence of the higher concentrations of the above-mentioned higher alcohols in the mash with a higher initial extract of 17% (\(w/w\)) was also the higher concentrations of the acetate esters of these alcohols, i.e., 3-methylbutyl acetate, 2-methylbutyl acetate, and 2-phenylethylly acetate, as well as the propionic acid ester of isoamyl alcohol, compared to the mash with a lower initial extract of 10% (\(w/w\)). Fermentation of the more extractable rye mash also yielded higher ethanol concentrations, resulting in a significant effect of the extract on the increase in the major ethyl esters, i.e., ethyl acetate and ethyl formate, as well as the minor esters, i.e., ethyl propionate, ethyl butyrate, ethyl isovalerate, ethyl valerate, and ethyl hexanoate. The statistical analysis also demonstrated the yeast strain's effect on certain esters' concentrations. The mash fermented by SB yeast had higher concentrations of most of the esters determined.