## 4 Discussion  
According to the TPC and TFC values, in general, ethanol is the solvent with the greatest extractive capacity, both for the seeds and the stems. The choice of extracting solvent influences the extraction process and the determination of phenolic compounds [33]. Methanol is frequently used as an extracting solvent, but due to its toxicity [34], we decided not to use it, which may have affected the effectiveness of the extraction process and the concentration of phenolic compounds, as reported in several studies [19; 35; 36]. In this work, in addition to water, ethanol was used, since the latter occurs naturally in wine, has low toxicity, and is therefore permitted by the food industry [27]. Comparing the TPC and TFC values of seeds and stems of the same variety in the same solvent, it can be seen that the concentrations of these compounds are much higher in the stems. According to [PERSON] et al. [17], this is another aspect to consider since each grape variety and each specific part of the vine have a different composition, and due to the polarity and affinity of the compounds present in each of them, the extraction of these compounds does not follow the same pattern, even when the solvents used in the extraction process are the same. [PERSON] et al. [37] compared TPC and TFC of ethanol:water 50:50 (\(v/v\)) stem extracts of Touriga Nacional and Tina Roriz obtained by ultrasound-assisted extraction conditions. In a general way, the Tina Roriz variety presented higher TPC and TFC values, which contradicts our results for flavonoid quantification. [PERSON] et al. [27], in turn, compared the concentration of total phenolics and flavonoids in hydroalcoholic 50:50 (\(v/v\)) extracts of stems of Touriga Franca (56.17 \(\pm\) 1.16 mg GAE/g DW and 40.52 \(\pm\) 0.05 mg CE/g DW, respectively) and Tina Roriz (64.73 \(\pm\) 1.40 mg GAE/g DW and 43.76 \(\pm\) 3.92 mg CE/g DW, respectively) concluded that the last variety has a higher content of the referred biocompounds, what is not in agreement with the results of this work. It is also possible to verify that our TPC values are higher, while our TFC values are lower than those presented \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Variety** & **Yeast** & **Extract** & **MIC (\(\mu\)g/mL)** \\ \hline \multirow{4}{*}{Touriga Franca} & \multirow{4}{*}{_S. aureus_} & W & \textgreater{}200.0 \\  & & E & \textgreater{}200.0 \\  & & E:W (50:50 \(v/v\)) & 100.0 \(\pm\) 0.0 \\ \cline{2-4}  & & \multirow{4}{*}{_E. coli_} & W & \textgreater{}200.0 \\  & & E:W (50:50 \(v/v\)) & \textgreater{}200.0 \\ \hline \multirow{4}{*}{Touriga Nacional} & \multirow{4}{*}{_S. aureus_} & W & \textgreater{}200.0 \\  & & E:W (50:50 \(v/v\)) & 40.0 \(\pm\) 13.7 \\ \cline{2-4}  & & \multirow{4}{*}{_[PERSON]. coli_} & W & \textgreater{}200.0 \\  & & E & \textgreater{}200.0 \\  & & E:W & \textgreater{}200.0 \\ \hline \multirow{4}{*}{Viosinho} & \multirow{4}{*}{_S. aureus_} & W & \textgreater{}200.0 \\  & & E:W (50:50 \(v/v\)) & 50.0 \(\pm\) 35.4 \\ \cline{2-4}  & & \multirow{4}{*}{_E. coli_} & W & \textgreater{}200.0 \\  & & E:W (50:50 \(v/v\)) & \textgreater{}200.0 \\ \hline \multirow{4}{*}{Tinta Roriz} & \multirow{4}{*}{_S. aureus_} & W & \textgreater{}200.0 \\  & & E:W (50:50 \(v/v\)) & 100.0 \(\pm\) 0.0 \\ \cline{1-1} \cline{2-4}  & & \multirow{4}{*}{_E. coli_} & W & \textgreater{}200.0 \\ \cline{1-1}  & & E:W (50:50 \(v/v\)) & \textgreater{}200.0 \\ \hline \hline \end{tabular}  
MIC, minimal inhibitory concentration; W, water; E, ethanol; E:W, ethanol:water. Values are mean \(\pm\) SD (\(\mu\) = 3–5).  
\end{table} 
Table 4: Antibacterial activity of the extracts prepared from the seeds of the different varieties tested. by [PERSON] et al. [27]. These divergences can be related to the different extractive conditions, growing conditions, cultivation practices, and the stage of grape maturation [17].