## 2 Results
### Polyphenol Content and Antioxidant Activity of Apple Wines  
The content of total polyphenols and antioxidant activity was determined in wines aged in the presence of wood chips and in oak barrels (Table 2).  
The results demonstrated a notable degree of variability. The ageing of apple wines in the presence of oak wood chips was found to result in the greatest increase in polyphenol content (Table 2), with the greatest variation observed in the case of lightly toasted chips. The analysis revealed that wines aged with oak chips exhibited a higher concentration of polyphenols than those aged with maple, apple and cherry chips, with the difference reaching 40%, 41% and 54%, respectively. Notably, wines aged with lightly toasted cherry chips exhibited the lowest total polyphenol content. In the case of oak and maple chips, a decrease in the polyphenol content was observed with an increasing degree of toasting, although the differences were statistically significant only for wines with oak chips. The polyphenol content of wines aged in the presence of apple and cherry chips was not found to be dependent on the degree of chips toasting. It was observed that the ageing of wines in oak barrels significantly (over fourfold) increased the content of total polyphenols, in comparison to wines aged in the presence of oak chips.  
The highest antioxidant activity was observed in wines aged with oak wood chips (Table 2). In the case of other wood species, the antioxidant potential of the wines was more uniform, and the observed differences were not statistically significant. Wines aged in the presence of heavy-toasted wood chips exhibited lower antioxidant activity than wines aged with medium-toasted wood chips, although the observed differences were statistically significant only in the case of oak chips. Apple wines aged in oak barrels exhibited an antiradical potential that was over four times higher than wines aged in the presence of oak chips (Table 2). The antioxidant activity of the wines was found to be closely correlated with the total polyphenol content, with a correlation coefficient of 0.99.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{4}{c}{**Toasting Level**} \\ \cline{2-5}
**Parameters** & **Lightly Toasted** & **Medium-Toasted** & **Heavily Toasted** & **Barrel** \\ \cline{2-5}  & & **1 Month** & & **1 Year** \\ \hline Total polyphenol content (TPC) & & & & \\ \(\left[\text{mg of }(+)\text{-catechin}/100\text{ mL}\right]\) & & & & \\ Oak & \(152.72\pm 4.17\)\({}^{\text{a}}\) & \(142.87\pm 11.48\)\({}^{\text{b}}\) & \(124.08\pm 2.99\)\({}^{\text{c}}\) & \(640.15\pm 24.45\)\({}^{\text{g}}\) \\ Maple & \(110.89\pm 5.32\)\({}^{\text{d,f}}\) & \(107.48\pm 2.34\)\({}^{\text{d,f}}\) & \(106.73\pm 3.92\)\({}^{\text{d,e}}\) & — \\ Apple & \(108.24\pm 1.99\)\({}^{\text{d,f}}\) & \(108.94\pm 2.74\)\({}^{\text{d,f}}\) & \(111.88\pm 0.50\)\({}^{\text{d}}\) & — \\ Cherry & \(98.71\pm 0.10\)\({}^{\text{e}}\) & \(105.72\pm 1.75\)\({}^{\text{d,e}}\) & \(102.65\pm 0.71\)\({}^{\text{e,f}}\) & — \\ \hline \hline \multicolumn{5}{c}{Antioxidant activity [mg of \(\text{Trolox}/100\text{ mL}\)]} & \(52.07\pm 0.60\)\({}^{\text{a}}\) & \(45.52\pm 0.41\)\({}^{\text{b}}\) & \(219.87\pm 3.19\)\({}^{\text{c}}\) \\ Oak & \(42.53\pm 0.98\)\({}^{\text{b}}\) & \(43.64\pm 1.24\)\({}^{\text{b}}\) & \(42.34\pm 0.79\)\({}^{\text{b}}\) & — \\ Apple & \(42.30\pm 0.17\)\({}^{\text{b}}\) & \(43.02\pm 0.17\)\({}^{\text{b}}\) & \(42.84\pm 1.35\)\({}^{\text{b}}\) & — \\ Cherry & \(41.73\pm 1.27\)\({}^{\text{b}}\) & \(44.37\pm 0.81\)\({}^{\text{b}}\) & \(43.35\pm 2.96\)\({}^{\text{b}}\) & — \\ \hline \hline \end{tabular}  
* The same letters within the analysed parameter indicate no statistical significance for \(p<0.05\).  
\end{table}
Table 2: The content of polyphenols in wines and their antioxidant activity, which have been aged in the presence of wood.