# Evaluation of Probiotic _Saccharomyces boulardii_ Yeast as a Distillery Strain
## 3 Results and Discussion
### HPLC Analysis of Fermented Media
#### 3.2.2 Results of HPLC Analysis of Rye Mash After Fermentation  
All strains utilised maltotriose from 10 \({}^{\circ}\)Blg rye mash to a similar extent. In the case of maltose, the highest residual amount was recorded for SB yeast (0.74 g/L), while the highest utilisation of this sugar was observed for ER yeast, with 0.26 g/L remaining. Similarly, the highest amount of residual sugar was recorded for the probiotic strain for glucose. The results for the other two yeasts were significantly lower. The opposite results were observed for xylose, where for mash fermented with _S. boulardii_ the lowest concentration (0.31 g/L) of this sugar was assayed. Significantly higher xylose concentrations were observed for both ER and TD reference strains. The results for arabinose concentrations in mashes fermented by strains SB and ER were not statistically different but were higher than those obtained for TD yeast (0.05 g/L).  
The citric acid concentration varied between 0.89 and 0.97 g/L. The control strain used resulted in statistically similar succinic acid content, close to 0.91 g/L. In comparison, the same acid in the medium fermented by probiotic yeast was only 0.74 g/L, significantly different from the other two.  
The highest amount of ethanol was noted for the ER yeast, at 38.51 g/L, while for SB and TD, this value was similar and close to 37.4 g/L. Compared to the results obtained after fermentations of 10 \({}^{\circ}\)Blg molasses, higher ethanol concentrations were observed for all yeasts. The difference in ethanol production when comparing the 10 \({}^{\circ}\)Blg molasses and the 10 \({}^{\circ}\)Blg rye wort medium was for strain SB, with 7.45 g/L; strain ER, with 7.13 g/L; and strain TD, with 5.57 g/L (Tables 2 and 4).  
Maltose and maltotriose are sugars formed during the hydrolysis of starch of rye mash. The highest amount of maltotriose remaining in the 17.5 \({}^{\circ}\)Blg rye mash (Table 5) was recorded after fermentation with TD yeast and was 0.85 g/L. At the same time, in the other two cases (ER and SB), this result was close to 0.75 g/L, and no statistically significant difference was observed between these two strains.  
The highest amount of maltose remaining in the mash was recorded for SB yeast, at 0.58 g/L, while the lowest amount was observed for the sample using TD yeast, at 0.39 g/L.  
In the case of xylose in the 17.5 \({}^{\circ}\)Blg rye mash, as for the 10 \({}^{\circ}\)Blg mash from the same raw material, the lowest amount of this compound was observed after fermentation by the SB strain. The results of residual arabin concentrations oscillated around 0.21 g/L and were not statistically different for the strains tested.  
Comparing the amount of ethanol produced, it is apparent that the highest amount was produced by SB yeast (66.37 g/L). The least amount of ethanol (63.12 g/L) was produced during the fermentation of this mash by ER yeast, which at the same time showed the highest amount of glycerol produced (8.89 g/L). The difference in the ethanol produced between the 17.5 \({}^{\circ}\)Blg rye mash and the 17.5 \({}^{\circ}\)Blg molasses worst was, in favour of the rye mash, for the probiotic yeast, at 20.32 g/L, while for reference strains, it was 9.71 g/L for ER and 5.4 g/L for TD. As in the case of comparing the fermentation effects of a 10 \({}^{\circ}\)Blg rye mash to a 10 \({}^{\circ}\)Blg molasses wort, the most significant increase in ethanol production in the rye mash was observed for the SB yeast.  
Similarly to the 17.5 \({}^{\circ}\)Blg molasses medium, SB yeast recorded the lowest glycerol content in both rye mashes: 4.92 g/L for the 10 \({}^{\circ}\)Blg rye mash and 8.23 g/L for the 17.5 \({}^{\circ}\)Blg rye mash.