## 3 Results and Discussion
### Ethanol, Organic Acids, and Residual Sugar Concentration  
The results of sugars (glucose, fructose, sorbitol), organic acids (malic acid, lactic acid, acetic acid), and ethanol in chokeberry juice during fermentation (30 \({}^{\circ}\)C for 48 h) and storage (4 \({}^{\circ}\)C for 4 weeks) are presented in Table 2.  
In general, organic acids pose another important component of food, as their presence and composition strongly affects the taste of food. Specifically, lactic acid is a natural  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Time** & **Malic Acid** & **Lactic Acid** & **Acetic Acid** & **Glucose** & **Fructose** & **Sorbitol** & **Ethanol** \\ \hline \multicolumn{8}{c}{**g/L**} & \multicolumn{8}{c}{**(\% v/v)**} \\ \hline
0 h & & 4.9 \(\pm\) 0.18 & nd & nd & 11.2 \(\pm\) 0.19 & 9.1 \(\pm\) 0.39 & 20.1 \(\pm\) 0.20 & nd \\ \hline \multirow{2}{*}{48 h} & UF & 4.6 \(\pm\) 0.19 \({}^{\text{a}}\) & nd & nd & 18.3 \(\pm\) 0.07 \({}^{\text{a}}\) & 13.4 \(\pm\) 0.06 \({}^{\text{a}}\) & 24.4 \(\pm\) 0.15 \({}^{\text{a}}\) & nd \\  & F & 4.1 \(\pm\) 0.35 \({}^{\text{b}}\) & 0.2 \(\pm\) 0.05 & nd & 16.1 \(\pm\) 0.15 \({}^{\text{b}}\) & 12.1 \(\pm\) 0.21 \({}^{\text{b}}\) & 24.3 \(\pm\) 0.18 \({}^{\text{a}}\) & nd \\ \hline \multirow{2}{*}{1 st week} & UF & 4.6 \(\pm\) 0.21 & nd & nd & 19.1 \(\pm\) 0.11 \({}^{\text{a}}\) & 16.9 \(\pm\) 0.09 \({}^{\text{a}}\) & 22.9 \(\pm\) 0.05 \({}^{\text{a}}\) & nd \\  & F & nd & 8.9 \(\pm\) 0.15 & nd & 15.6 \(\pm\) 0.19 \({}^{\text{b}}\) & 11.8 \(\pm\) 0.12 \({}^{\text{b}}\) & 22.6 \(\pm\) 0.35 \({}^{\text{a}}\) & nd \\ \hline \multirow{2}{*}{2 nd week} & UF & 4.6 \(\pm\) 0.12 & nd & nd & 19.9 \(\pm\) 0.23 \({}^{\text{a}}\) & 17.4 \(\pm\) 0.15 \({}^{\text{a}}\) & 21.2 \(\pm\) 0.41 \({}^{\text{a}}\) & nd \\  & F & nd & 9.1 \(\pm\) 0.21 & 0.1 \(\pm\) 0.02 & 13.8 \(\pm\) 0.21 \({}^{\text{b}}\) & 10.9 \(\pm\) 0.08 \({}^{\text{b}}\) & 21.1 \(\pm\) 0.19 \({}^{\text{a}}\) & nd \\ \hline \multirow{2}{*}{3 rd week} & UF & 4.5 \(\pm\) 0.27 & nd & nd & 22.4 \(\pm\) 0.31 \({}^{\text{a}}\) & 18.3 \(\pm\) 0.11 \({}^{\text{a}}\) & 21.5 \(\pm\) 0.15 \({}^{\text{a}}\) & nd \\  & F & nd & 9.3 \(\pm\) 0.39 & 0.1 \(\pm\) 0.04 & 14.0 \(\pm\) 0.18 \({}^{\text{b}}\) & 10.9 \(\pm\) 0.11 \({}^{\text{d}}\) & 21.3 \(\pm\) 0.24 \({}^{\text{a}}\) & nd \\ \hline \multirow{2}{*}{4 th week} & UF & 4.6 \(\pm\) 0.11 & nd & nd & 22.9 \(\pm\) 0.15 \({}^{\text{a}}\) & 20.0 \(\pm\) 0.04 \({}^{\text{a}}\) & 22.5 \(\pm\) 0.45 \({}^{\text{a}}\) & nd \\  & F & nd & 9.4 \(\pm\) 0.48 & 0.1 \(\pm\) 0.05 & 14.4 \(\pm\) 0.11 \({}^{\text{b}}  
preservative that besides enhancing the preservation time of foods can act as a flavoring substance, improving the profile of organoleptic characteristics of fermented foods. In addition, the produced lactic acid, especially at 4 weeks of fermentation at 4 \({}^{\circ}\)C, proves the existence of fermentation of the juice by the presence of the potentially probiotic strain SP5. Malic acid, which is considered as the main organic acid of chokeberry, was detected up to 48 h of fermentation and then no amount was detected. The main reason is that the probiotic strain metabolized malic to lactic acid (malolactic fermentation). Indeed, the levels of lactic acid significantly increased during fermentation at 4 \({}^{\circ}\)C and remained at high levels during the 4 weeks (>9.0 g/L). Acetic acid concentration was determined in traces after the second week of fermentation at 4 \({}^{\circ}\)C and remained at very low concentration during the rest period (0.1 g/L). Acetic acid probably was slightly produced by citric acid, as other researchers have reported in lactic acid fermentation of fruit juices [35]. Ethanol did not appear in significant levels as well. No significant content of ethanol was observed during any of the studied time periods. This outcome was mostly expected as lactic acid bacteria are known to metabolize sugar molecules to acids such as lactic and malic acid [7; 13].