# The Fermentation of Orange and Black Currant Juices by the
## 3 Results and Discussion
### Parameters of the Fermented Juices
The concentration of citric acid in the fermented currant juice ranged from 4.90 \(\pm\) 0.27 to 6.75 \(\pm\) 0.27 g/L. The concentration of this acid in the unfermented currant juice was 5.57 \(\pm\) 0.23 g/L. It can be concluded that there was a slight increase in the citric acid concentration for the samples fermented with glucose, regardless of the yeast used. The malic acid concentration of the fermented currant juice samples ranged from 0.28 \(\pm\) 0.01 to 0.31 \(\pm\) 0.01 g/L, while the succinic acid concentration ranged from 0.13 \(\pm\) 0.01 to 0.89 \(\pm\) 0.04 g/L. When we compare these results with the levels of acids in the juices before fermentation, it can be seen that the concentrations of both acids were increased (_p_ < 0.05) for all the fermented samples. [PERSON] et al. reported that the concentrations of citric, malic, and succinic acids after alcoholic fermentation of black currant juice carried by the yeasts _S.cerevisiae_ and _S. Dayanus_ were in the ranges 30.3-35.1 g/L (for citric acid); 2.6-2.8 g/L (for malic acid); and 0.5-0.9 g/L (for succinic acid) [19]. The ethanol, glycerol, and TPC concentration in the samples after fermentation are shown in Tables 4 and 5. The tables above show the results of the ethanol, glycerol, and total phenolic compounds (TPCs) concentrations of the fermented orange (Table 4) and black currant juices (Table 5). The ethanol concentration of the orange juices fermented without added glucose was 27.72 \(\pm\) 1.28 and 26.45 \(\pm\) 1.53 g/L for the OR \"0\" and OR + DAP samples, respectively. In contrast, the glycerol concentration in these samples was 2.42 \(\pm\) 0.13 and 2.56 \(\pm\) 0.12 g/L, respectively. These results demonstrate the lack of a positive effect of DAP on the alcohol formation efficiency during orange juice fermentation by the _S. cerevisiae_ var. _boulardii_ strain. Adding glucose to the orange juice undergoing fermentation resulted in a significant increase in the alcohol produced. For the OR + G sample fermented by the _S. cerevisiae_ var. _boulardii_ strain, the ethanol concentration was equal to 65.58 \(\pm\) 1.84 g/L. In contrast, for the same sort fermented by the _S. Dayanus_ yeast, the final ethanol concentration was equal to 71.23 \(\pm\) 1.62 g/L, meaning that the use of the _S. Dayanus_ strain increased the alcoholic fermentation yield of approximately 8.4%, compared to the use of the probiotic yeast strain. [PERSON] et al. [30], for glucose-enriched juices after the fermentation of orange juice by the \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Et OH** & **Glyc OH** & **TPC** \\ \cline{2-4}  & & **[g/L]** & **mg/100 mL** \\ \hline OR “0” & 27.72 \(\pm\) 1.28 & 2.42 \(\pm\) 0.13 & 49.81 \(\pm\) 0.61 \\ OR + DAP & 26.45 \(\pm\) 1.53 & 2.56 \(\pm\) 0.12 & 48.27 \(\pm\) 0.53 \\ OR + G & 65.58 \(\pm\) 1.84 & 5.58 \(\pm\) 0.22 & 47.81 \(\pm\) 0.56 \\ OR Sb + G & 71.23 \(\pm\) 1.62 & 4.83 \(\pm\) 0.23 & 43.36 \(\pm\) 0.42 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Ethanol, glycerol, and TPC content in the orange juice after fermentation. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Et OH** & **Glyc OH** & **TPC** \\ \cline{2-4}  & & **[g/L]** & **mg/100 mL** \\ \hline BC “0” & 19.67 \(\pm\) 1.02 & 2.28 \(\pm\) 0.12 & 84.10 \(\pm\) 0.38 \\ BC + DAP & 16.14 \(\pm\) 1.12 & 1.95 \(\pm\) 0.09 & 83.80 \(\pm\) 0.45 \\ BC + G & 66.05 \(\pm\) 2.36 & 4.93 \(\pm\) 0.28 & 83.10 \(\pm\) 0.36 \\ BC Sb + G & 72.87 \(\pm\) 2.42 & 4.68 \(\pm\) 0.21 & 81.20 \(\pm\) 0.41 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Ethanol, glycerol, and TPC content in the black currant juice after fermentation. S. cerevisiae_ UFLA CA1174 strain, recorded ethanol (58.13 g/L) and glycerol (5.35 g/L) concentrations similar to our results presented in Table 4. [PERSON] et al. [31] obtained final ethanol concentrations close to 6.5%, which is consistent with our results.