## 3 Results and Discussion
### Content of TPC Using the Folin-Ciocalteu Reagent Method
#### 3.1.1 Extracts Obtained Using Shaking Solvent Extraction (SSE)
A statistical analysis showed that the content of total polyphenols in the tested extracts did not differ significantly between the shaking time variants used. Similarly, [PERSON] et al. [32] compared different extraction times and found that this parameter did not significantly affect the polyphenol content in the extracts. Based on the analysis of the obtained results, extracts shaken for 30 min were selected for further determinations, in which 55.1 mg GAE/1 g of DW of polyphenols was determined. [PERSON] et al. [46] also showed that the content of flavonoids in apple extracts is the highest after approximately 30 min of extraction (at room temperature). The choice of this time variant was particularly beneficial for most water-alcoholic extracts, and they contained the most phenolic compounds. Water-methanol extracts were characterised by the significantly highest polyphenol content among all extracts prepared using the solvent shaking extraction method (66.8 mg GAE/1 g of DW). However, water-ethanol extracts contained significantly more phenolic compounds (57.3 mg GAE/1 g of DW) than water extracts (35.8 mg GAE/1 g of DW). Other authors also confirmed in their research that mixtures of methanol or ethanol with water are a more efficient extractant than water or pure ethanol alone [47]. When examining the influence of apple leaf cultivar on the polyphenol content in extracts obtained using the classical method, different results were obtained than for extracts obtained using the UAE method, which means that in the case of extraction by shaking, the leaf cultivar had a significant impact on the content of phenolic compounds (\(p<0.05\)). Extracts prepared from the leaves of the Ligol cultivar were characterised by the significantly highest polyphenol content (61.8 mg GAE/1 g of DW). The two-factor analysis of variance of the polyphenol content in extracts shaken for 30 min showed that the water and methanol extracts from the Ligol leaf cultivar were characterised by the significantly highest content of total polyphenols among all extracts \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Type of Solvent** & **Apple Cultivar** & **Shaking Time [min]** & **TPC** \\ \hline \multirow{8}{*}{Ligol} & & 1 & 58.5 \(\pm\) 2.0 \\ \cline{2-4}  & & 30 & 67.4 \(\pm\) 1.8 \\ \cline{2-4}  & & 60 & 67.3 \(\pm\) 3.1 \\ \cline{2-4}  & & 90 & 65.8 \(\pm\) 1.9 \\ \cline{2-4}  & & 1 & 52.8 \(\pm\) 3.0 \\ \cline{2-4} Water-ethanol & & 30 & 59.0 \(\pm\) 2.0 \\ \cline{2-4} (60:40, \(v/v\)) & & 60 & 58.5 \(\pm\) 1.3 \\ \cline{2-4}  & & 90 & 58.4 \(\pm\) 1.2 \\ \cline{2-4}  & & 1 & 47.9 \(\pm\) 1.1 \\ \cline{2-4}  & & 30 & 55.4 \(\pm\) 2.0 \\ \cline{2-4}  & & 60 & 49.1 \(\pm\) 1.6 \\ \cline{2-4}  & & 90 & 47.9 \(\pm\) 3.3 \\ \hline \hline \end{tabular} Mean values for triplicates \(\pm\) SD. Abbreviations: TPC—Total phenolic content in extracts (mg GAE/1 g of DW); GAE: gallic acid equivalent; DW: dry weight.  
\end{table} 
Table 1: _Cont._prepared by this method and amounted to 80.9 mg GAE/1 g of DW. Water-methanol extracts from the leaves of the Gloster cultivar (66.7 mg GAE/1 g of DW) and water-ethanol extracts from the Ligol cultivar (67.4 mg GAE/1 g of DW) did not differ significantly from each other and contained significantly more total polyphenols than other extracts. Also, the water-alcoholic extracts from the leaves of the Gala cultivar did not differ significantly from each other, but the water-methanol extract from the leaves of this cultivar contained significantly more polyphenols (60.6 mg GAE/1 g of DW) than the water-ethanol extract made from the leaves of the cultivar Gloster (55.3 mg GAE/1 g of DW). Water extracts obtained using the classical extraction method were characterised by a significantly lower content of total polyphenols than water-alcoholic extracts.