## 3 Results and Discussion
### Preparation and Characterization of Sea Buckthorn Leaves Kombucha
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **Fermentation, Days** & \begin{tabular}{c} **Proanthocyanidins,** \\ **gce/L** \\ \end{tabular} & \
\begin{tabular}{c} **TPC, ggae/L** \\ \end{tabular} &
\begin{tabular}{c} **DPPH, \%** \\ \end{tabular} \\ \hline \multirow{8}{*}{L4-100} & 0 & 7.30 \(\pm\) 0.21 bc & 1.05 \(\pm\) 0.02 cd & 84.75 \(\pm\) 0.23 k \\  & 1 & 8.28 \(\pm\) 0.34 d & 0.89 \(\pm\) 0.01 a & 74.39 \(\pm\) 0.57 hi \\  & 3 & 7.74 \(\pm\) 0.35 cd & 1.03 \(\pm\) 0.03 bc & 80.29 \(\pm\) 0.13 jk \\  & 5 & 7.01 \(\pm\) 0.29 b & 1.09 \(\pm\) 0.02 de & 77.06\(\pm\) 0.29 ij \\  & 7 & 6.11 \(\pm\) 0.22 a & 1.19 \(\pm\) 0.02 f & 74.75 \(\pm\) 0.08 hi \\  & 10 & 5.76 \(\pm\) 0.28 a & 1.21 \(\pm\) 0.03 f & 72.83 \(\pm\) 0.20 g \\ \hline \multirow{8}{*}{L4-75} & 0 & 7.39 \(\pm\) 0.35 bc & 1.03 \(\pm\) 0.02 bc & 83.92 \(\pm\) 0.12 ik \\  & 1 & 7.66 \(\pm\) 0.27 c & 0.98 \(\pm\) 0.01 ab & 76.25 \(\pm\) 1.00 hi \\  & 3 & 8.99 \(\pm\) 0.38 e & 0.96 \(\pm\) 0.02 ab & 81.53 \(\pm\) 0.36 jk \\  & 5 & 7.47 \(\pm\) 0.31 bc & 1.03 \(\pm\) 0.01 bc & 79.87 \(\pm\) 0.36 j \\  & 7 & 7.62 \(\pm\) 0.35 c & 1.08 \(\pm\) 0.03 de & 77.02 \(\pm\) 0.07 i \\  & 10 & 6.46 \(\pm\) 0.17 ab & 1.11 \(\pm\) 0.01 e & 75.53 \(\pm\) 0.06 hi \\ \hline \multirow{8}{*}{L4-50} & 0 & 7.81 \(\pm\) 0.36 cd & 0.98 \(\pm\) 0.01 ab & 83.30 \(\pm\) 0.12 l \\  & 1 & 8.20 \(\pm\) 0.39 d & 0.99 \(\pm\) 0.01 ab & 77.26 \(\pm\) 3.25 hi \\ \cline{1-1}  & 3 & 8.52 \(\pm\) 0.25 de & 0.94 \(\pm\) 0.02 ab & 76.78 \(\pm\) 0.95 h \\ \cline{1-1}  & 5 & 7.53 \(\pm\) 0.28 bc & 1.02 \(\pm\) 0.04 bc & 72.09 \(\pm\) 0.91 g \\ \cline{1-1}  & 7 & 7.51 \(\pm\) 0.11 bc & 1.01 \(\pm\) 0.04 bc & 75.89 \(\pm\) 0.01 h \\ \cline{1-1}  & 10 & 6.38 \(\pm\) 0.20 ab & 1.12 \(\pm\) 0.03 e & 67.94 \(\pm\) 0.08 f \\ \hline \multirow{8}{*}{L4-25} & 0 & 7.75 \(\pm\) 0.21 cd & 1.01 \(\pm\) 0.01 bc & 82.63 \(\pm\) 0.35 l \\  & 1 & 6.81 \(\pm\) 0.28 b & 0.93 \(\pm\) 0.01 ab & 78.03 \(\pm\) 0.57 ij \\ \cline{1-1}  & 3 & 8.35 \(\pm\) 0.39 d & 0.92 \(\pm\) 0.01 ab & 60.57 \(\pm\) 0.57 e \\ \cline{1-1}  & 5 & 7.53 \(\pm\) 0.28 bc & 1.01 \(\pm\) 0.02 bc & 48.50 \(\pm\) 0.28 c \\ \cline{1-1}  & 7 & 7.06 \(\pm\) 0.31 b & 0.99 \(\pm\) 0.02 ab & 32.53 \(\pm\) 0.31 a \\ \cline{1-1}  & 10 & 6.38 \(\pm\) 0.17 ab & 1.05 \(\pm\) 0.02 cd & 31.88 \(\pm\) 0.13 a \\ \hline \multirow{8}{*}{G-100} & 0 & 7.19 \(\pm\) 0.31 b & 0.90 \(\pm\) 0.01 a & 86.97 \(\pm\) 0.03 m \\  & 1 & 7.88 \(\pm\) 0.29 cd & 0.99 \(\pm\) 0.02 ab & 78.15 \(\pm\) 1.14 i j \\ \cline{1-1}  & 3 & 8.36 \(\pm\) 0.36 d & 1.03 \(\pm\) 0.02 bc & 64.33 \(\pm\) 0.18 e \\ \cline{1-1}  & 5 & 7.06 \(\pm\) 0.29 b & 0.91 \(\pm\) 0.04 a & 55.77 \(\pm\) 0.26 d \\ \cline{1-1}  & 7 & 5.97 \(\pm\) 0.21 a & 0.91 \(\pm\) 0.04 a & 60.62 \(\pm\) 0.09 e \\ \cline{1-1}  & 10 & 6.13 \(\pm\) 0.27 a & 0.93 \(\pm\) 0.03 ab & 43.73 \(\pm\) 2.02 b \\ \hline \hline \end{tabular}  
* Data values are expressed as means with the standard deviation (\(n=3\)). Different lowercase letters a–m in the column show that values are significantly different (\(p<0.05\)).  
\end{table} 
Table 3: Proanthocyanidins, TPC concentrations, and antioxidant efficacy parameters in kombucha during fermentation. Biological active compounds such as phenolic compounds or proanthocyanidins are secondary metabolites found abundantly in plant-based products. They possess notable antioxidant properties that contribute positively to human health. Additionally, these compounds influence the aroma, flavor, and color characteristics of food products [45; 47]. They are essential in kombucha beverages due to their health-promoting characteristics. Hence, alternative substrates obtained from various plants may have the potential for biologically active compounds [48]. During the study, the proanthocyanidin content of the original tea samples ranged from 7.19 g\({}_{\text{CE}}\)/L to 7.81 g\({}_{\text{CE}}\)/L, depending on the ratio of sea buckthorn leaves to green tea (Table 3).