## 3 Results  
### Studies of the Influence of Technological Parameters on Fermentation Stems and Kinetic Modelling  
#### 3.1.1 Studies on the Effect of Lactic Acid Bacteria Strains  
Studies on the effect of lactic acid bacteria strains on changes in antioxidant activity (AA), total polyphenol content (TPC), and lactic acid efficiency (LA\({}_{\rm e}\)) are presented in Table 2.  
Based on the results obtained using GC-MS (Figure S1), it was found that the highest lactic acid yield was obtained after 9 days of fermentation in the presence of \(L\). _salivarius_ LY_0652 (FSE-2, LA\({}_{\rm e}\) = 63% \(\pm\) 1), \(L\). _brevis_ LY_1120 (FSE-3, LA\({}_{\rm e}\) = 69% \(\pm\) 1), \(L\). _rhamous_ MI-0272 (FSE-5, LA\({}_{\rm e}\) = 89% \(\pm\) 1), and \(L\). _plantarum_ MI-0102 (FSE-6, LA\({}_{\rm e}\) = 85% \(\pm\) 1). In the presence of \(L\). _reuteri_ MI_0168 and \(L\). _acidophilus_ MI-0078 strains, the highest LA yields of 80% \(\pm\) 1 (for FSE-1) and 77% \(\pm\) 1 (for FSE-4) were obtained after 10 days of running the process. For further studies on the effect of initial sugar content on the course of stem fermentation, strain \(L\). _rhamous_ MI-0272 and a fermentation time of 9 days were selected due to the highest yield of lactic acid formed during the process (89% \(\pm\) 1). These conditions also yielded the highest value of antioxidant activity (AA = 4.23 mmol Tx/L \(\pm\) 0.13) and the highest content of phenolic compounds (TPC = 2.82 mmol GA/L \(\pm\) 0.18) (Table 2). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Fermented Stems**} & **Fermentation** & \multirow{2}{*}{**AA**} & **TPC** & **LA\({}_{\rm e}\)** \\ \cline{3-4}  & **Time** & & & \\ \cline{2-4}
**Microorganism** & **Days** & **mmol Tx/L** & **mmol GA/L** & **\%** \\ \hline \multirow{4}{*}{\(L\). _reuteri_ MI\_0168} & 1 & 4.12 \(\pm\) 0.11 & 1.91 \(\pm\) 0.09 & 40 \(\pm\) 1 \\  & 5 & 4.20 \(\pm\) 0.17 & 2.53 \(\pm\) 0.16 & 53 \(\pm\) 1 \\  & 9 & 4.23 \(\pm\) 0.19 & 2.83 \(\pm\) 0.20 & 79 \(\pm\) 1 \\  & 10 & 4.23 \(\pm\) 0.18 & 2.83 \(\pm\) 0.13 & 80 \(\pm\) 1 \\ \hline \multirow{4}{*}{\(L\). _salivarius_ LY\_0652} & 1 & 4.10 \(\pm\) 0.19 & 1.90 \(\pm\) 0.12 & 42 \(\pm\) 1 \\  & 5 & 4.18 \(\pm\) 0.11 & 2.52 \(\pm\) 0.19 & 52 \(\pm\) 1 \\  & 9 & 4.21 \(\pm\) 0.09 & 2.81 \(\pm\) 0.13 & 63 \(\pm\) 1 \\  & 10 & 4.21 \(\pm\) 0.21 & 2.81 \(\pm\) 0.11 & 58 \(\pm\) 1 \\ \hline \multirow{4}{*}{\(L\). _brevis_ LY\_1120} & 1 & 3.99 \(\pm\) 0.09 & 1.89 \(\pm\) 0.09 & 41 \(\pm\) 1 \\  & 5 & 4.00 \(\pm\) 0.07 & 2.44 \(\pm\) 0.03 & 56 \(\pm\) 1 \\  & 9 & 4.19 \(\pm\) 0.11 & 2.65 \(\pm\) 0.01 & 69 \(\pm\) 1 \\ \hline \multirow{4}{*}{\(L\). _acidophilus_ MI-0078} & 1 & 4.11 \(\pm\) 0.19 & 1.89 \(\pm\) 0.11 & 41 \(\pm\) 1 \\  & 5 & 4.13 \(\pm\) 0.14 & 2.44 \(\pm\) 0.12 & 58 \(\pm\) 1 \\ \cline{1-1}  & 9 & 4.22 \(\pm\) 0.19 & 2.65 \(\pm\) 0.11 & 70 \(\pm\) 1 \\ \cline{1-1}  & 10 & 4.22 \(\pm\) 0.16 & 2.65 \(\pm\) 0.11 & 77 \(\pm\) 1 \\ \hline \multirow{4}{*}{\(L\). _rhamous_ MI-0272} & 1 & 4.11 \(\pm\) 0.10 & 1.92 \(\pm\) 0.09 & 50 \(\pm\) 1 \\  & 5 & 4.19 \(\pm\) 0.11 & 2.52 \(\pm\) 0.21 & 85 \(\pm\) 1 \\ \cline{1-1}  & 9 & 4.23 \(\pm\) 0.11 & 2.82 \(\pm\) 0.13 & 89 \(\pm\) 1 \\ \cline{1-1}  & 10 & 4.23 \(\pm\) 0.13 & 2.82 \(\pm\) 0.15 & 87 \(\pm\) 1 \\ \hline \multirow{4}{*}{\(L\). _plantarum_ MI-0102} & 1 & 3.99 \(\pm\) 0.22 & 1.91 \(\pm\) 0.13 & 47 \(\pm\) 1 \\ \cline{1-1}  & 5 & 4.12 \(\pm\) 0.19 & 2.51 \(\pm\) 0.13 & 69 \(\pm\) 1 \\ \cline{1-1}  & 9 & 4.20 \(\pm\) 0.17 & 2.81 \(\pm\) 0.20 & 85 \(\pm\) 1 \\ \cline{1-1}  & 10 & 4.20 \(\pm\) 0.17 & 2.81 \(\pm\) 0.21 & 85 \(\pm\) 1 \\ \hline \end{tabular} Mean \(\pm\) SD (n = 3), process parameters: initial sugar content 3.20% inoculum content 3.20%, plant material content 1.60%, fermentation time 10 days.  
\end{table} 
Table 2: Studies on the effect of the type of microorganism (_L. reuteri_ MI_0168, _L. salivarius_ LY_0652, _L. brevis_ LY_1120, _L. acidophilus_ MI-0078, _L. rhumosus_ MI-0272, and _L.