## 3 Results and Discussion
### Individual Phenolic Compounds  
Table 5 displays the individual phenolic compounds identified in the four wines. First of all, it should be noted that the reference wine (RW) always presented the highest content of each phenolic compound with significant differences compared to the concentrations reached by any of the three sweet wines with different sugar levels.  
All of the sweet red wines, with different sugar levels, presented concentrations of some of the phenolic compounds analyzed that were in the order of 50% or even lower than the reference wine. In other words, in general, stopping the fermentation resulted in a greater difference in the level of simple phenolic compounds between the reference wine and the sweet wines than in the case of the anthocyanin compounds, where the differences were lower. For example, the concentrations of ruitin in SL25, SL50 and SL75, reached 54%, 48%, 46%, respectively, and quercetin-3-rhammoside was detected at between 55% and 46%. The contents of gallic acid in SL25, SL50 and SL75 reached 41%, 38%, 31%, respectively. The wine SL25 showed a 54% content for these compounds in relation to the RW wine, ranging from 39% for caffe acid to 82% for epicatechin. Contents in SL50 ranged from 38% to 79% (52% as average content), and SL75 ranged from 31% to 71% (46% as average content). No significant differences were found between SL50 and SL25 and SL75, but SL75 was significantly different from SL25. It is well known that anthocyanins are mainly extracted at the beginning of the alcoholic fermentation; therefore, their levels were more similar across the wines than the other phenolics, that have additional extraction at the end of the alcoholic fermentation.  
Catechin and epicatechin are compounds that provide astringency and color stability to wine. With respect to the RW, the sweet red wines reached epicatechin levels of 82% in SL25, 79% in SL50 and 71% in SL75; the only significant difference was between SL25 and SL75. In the case of catechin, similar results were registered, but with values around 20% lower than those for epicatechin, i.e., 57% in SL25, 56% in SL50 and 47% in SL75. Therefore, SL25 and SL50 wines were statistically similar with respect to these parameters, while the SL75 wine was considered statistically different from the rest of the wines, either sweet or the RW.  
For the rest of the individual phenolic compounds, there were no marked differences between the three types of sweet wines, with rather similar values.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Wine** & **Gallic Acid** & **Catechin** & **Caffeic Acid** & **Epicatechin** & **Rutin** & **Quercetin-3-Glucoside** & **Quercetin-3-Rhamoside** \\ \hline RW & 21.56 \(\pm\) 1.66 \({}^{\text{a}}\) & 34.4 \(\pm\) 2.13 \({}^{\text{a}}\) & 4.79 \(\pm\) 0.89 \({}^{\text{a}}\) & 14.54 \(\pm\) 2.03 \({}^{\text{a}}\) & 4.73 \(\pm\) 0.52 \({}^{\text{a}}\) & 9.52 \(\pm\) 1.15 \({}^{\text{a}}\) & 1.56 \(\pm\) 0.07 \({}^{\text{a}}\) \\ SL25 & 8.92 \(\pm\) 0.96 \({}^{\text{b}}\) & 19.73 \(\pm\) 1.12 \({}^{\text{b}}\) & 1.84 \(\pm\) 0.25 \({}^{\text{b}}\) & 11.87 \(\pm\) 0.91 \({}^{\text{b}}\) & 2.57 \(\pm\) 0.30 \({}^{\text{b}}\) & 5.27 \(\pm\) 0.72 \({}^{\text{b}}\) & 0.78 \(\pm\) 0.07 \({}^{\text{b}}\) \\ SL50 & 8.10 \(\pm\) 0.66 \({}^{\text{bc}}\) & 19.18 \(\pm\) 0.96 \({}^{\text{b}}\) & 1.87 \(\pm\) 0.16 \({}^{\text{b}}\) & 11.42 \(\pm\) 1.06 \({}^{\text{bc}}\) & 2.29 \(\pm\) 0.39 \({}^{\text{b}}\) & 4.59 \(\pm\) 0.32 \({}^{\text{b}}\) & 0.86 \(\pm\) 0.03 \({}^{\text{b}}\) \\ SL75 & 6.76 \(\pm\) 0.82 \({}^{\text{c}}\) & 16.34 \(\pm\) 1.31 \({}^{\text{c}}\) & 1.58 \(\pm\) 0.41 \({}^{\text{b}}\) & 10.37 \(\pm\) 1.52 \({}^{\text{c}}\) & 2.17 \(\pm\) 0.12 \({}^{\text{b}}\) & 4.46 \(\pm\) 0.51 \({}^{\text{b}}\) & 0.72 \(\pm\) 0.02 \({}^{\text{b}}\) \\ \hline \hline \end{tabular}
\end{table}
Table 5: Concentration of individual phenolic compounds in the wines in \(\text{m}\)\(\text{L}^{-1}\).