## 4 Discussion
For example, the black rose, chokeberry, and blackcurrant liqueurs stored at a temperature of 30 \({}^{\circ}\)C showed a significant reduction in antioxidant activity from 20% to 50% [9]. In another study, the antioxidant capacity of cherry liqueurs analyzed by the ABTS method changed during 24 weeks of storage, probably due to sugar addition and storage temperature. The antioxidant activity before storage at 15 \({}^{\circ}\)C was 11.56 umol Trolox/mL (without sugar added) and 11.77 umol Trolox/mL (with sugar added), whereas, after storage, it decreased to 10.83 and 10.68 umol Trolox/mL, respectively. Moreover, at 30 \({}^{\circ}\)C it was 12.28 umol Trolox/mL (without sugar added) and 12.62 umol Trolox/mL (with sugar added), while after storage--9.90 and 7.85 umol Trolox/mL [11]. [PERSON] et al. suggest that during the storage of wine, oxidation of principal polyphenic compounds would presumably lead to changes in the levels of antioxidants as a consequence of changes in the redox equilibrium [49]. A large group of polyphenols plays an important role in the human diet. Epidemiological studies have shown associations between the consumption of polyphenol-rich beverages and the prevention of diseases viz. cancers, diabetes, and cardiovascular [50; 51]. A high polyphenols content is responsible for the strong antioxidant properties of fruit [13; 50]. Polyphenols may have anti-inflammatory and/or inflammatory response stabilizing activities, which is very important in health maintenance and disease risk reduction. It turns out that diets rich in fruits are inversely associated with inflammatory stress, and the prevalence of diabetes and Alzheimer's disease is lower with increased fruit consumption [52]. In our research, all analyzed palewkas were characterized by a high content of total polyphenols. The total polyphenol content in our study ranged from 3.877 \(\pm\) 0.022 mg GA\(\cdot\)g\({}^{-1}\) for ratiafa prepared in 1997 to 8.232 \(\pm\) 0.045 mg GA\(\cdot\)g\({}^{-1}\) for plum nalewka prepared in 2019. [PERSON] et al. stated that the black rose, chokeberry, sloe, and mahonia fruits liqueurs had high total polyphenol contents of 671, 329, 271, and 218 GAE in 100 mL of liqueur, respectively. On the contrary, liqueurs made from raspberries, strawberries, and cornelian cherry were characterized by significantly lower total polyphenol content: 63.4, 82.0, and 99.0 GAE in 100 mL, respectively [9]. [PERSON] and [PERSON] analyzed various fruits nalewka containing elderberry, cranberry, rowanberry, raspberry, cherry, as well as nuts. The evaluated nalewkas were purchased in the local market or were produced at home. Authors stated that all evaluated alcoholic beverages were characterized by the content of total polyphenols--which varied from 83 mg GA/L in the case of rowanberry nalewka to 3649 mg GA/L for elderberry nalewka. Interestingly, homemade nalewka from raspberry contained over three times more total polyphenols (1811 mg GA/L) as compared with nalewka purchased locally marked (534 mg GA/L). It could be related, among others, to the different content of ethanol because nalewka produced homemade was characterized by a higher alcohol concentration of 45% (\(v/v\)), whereas commercial--25% (\(v/v\)) [13]. In our study, similarly to the antioxidant activity, the highest total polyphenol content was observed for the youngest nalewkas: 2018 and 2019 for ratiafa and 2017-2019 for cherry and plum nalewkas. Regardless of the type of nalewkas, three groups can be distinguished: the group of the oldest nalewkas from 1997, the group from 2013-2017, and the last one from 2018 and 2019 characterized by the highest total polyphenol content. Many factors may contribute to the reduction in polyphenols during storage, such as storage time, temperature, and sugar content, as well as the type of fruit from which the nalewka was made [9; 13]. For example, [PERSON] et al. found no significant change in the total polyphenol content of cherry liqueurs due to storage conditions.