## 2 Materials and Methods
### Antioxidant Activity  
DPPH radical scavenging activities of nalewkas were measured using a previously described technique [6; 43]. Briefly, an aliquot of 150 \(\mu\)L of nalewka was mixed with 2850 \(\mu\)L of DPPH radical solution in 96% (\(v/v\)) ethanol. After 10 min of incubation in the dark at room temperature, measurement of absorbance at 517 nm against 96% (\(v/v\)) ethanol was performed using Hitachi UV-Vis Spectrophotometer U-5100 (Hitachi High-Tech Science Corporation, Tokyo, Japan). Three independent samples of each examined nalewkas were prepared. The results are presented in mg Trolox:g\({}^{-1}\) of nalewka. Additionally, the antioxidant activity was expressed as a percentage of inhibition (%). The potential of scavenging ABTS radical by fruit nalewkas was measured using the method previously applied by [PERSON] et al. [43; 44]. Shortly, a 7 mM solution of ABTS (2,2\({}^{\prime}\)-azino-bis(3-ethylbenzothazoline-6-sulfonic acid)) in a 2.45 mM aqueous solution of potassium persulfate was used as a stock solution. After dissolving the components, the solution was incubated for 24 h in the dark at room temperature, then diluted with 50% (\(v/v\)) methanol to obtain a working solution of absorbance of 1.00 \(\pm\) 0.02 at 734 nm. Next, 2.5 mL of working ABTS solution and 0.025 mL of a studied nalewka were introduced into the spectrophotometric cuvette. After 6 min of incubation at room temperature, absorbance was measured. Each extract was evaluated in triplicate. The results are presented in mg Trolox:g\({}^{-1}\) of nalewka. The ferric ion reducing potential was measured with FRAP (ferric reducing antioxidant power) method as in previous studies [44]. The working solution was prepared by mixing 1 volume of 10 mM TPTZ (dissolved in 40 mM HCl), 1 volume of 20 mM FeCl\({}_{3}\), and 10 volumes of acetate buffer (pH 3.6). An aliquot of 2320 \(\mu\)L of the working solution was mixed with 80 \(\mu\)L of nalewka. The absorbance was measured after 15 min at 593 nm. The results are expressed as mg FeSO\({}_{4}\):g\({}^{-1}\) of nalewka  
In order to evaluate the reducing ability of cupric ions, the CUPRAC method with volume modification was applied according to the methodology described by [PERSON] et al. [45]. Shortly, 500 \(\mu\)L of 0.01 M aqueous CuCl\({}_{2}\) solution, 500 \(\mu\)L of 7.5 mM neocuproine solution in 96% ethanol, 500 \(\mu\)L of 1 M acetate buffer (pH 7), 300 \(\mu\)L of distilled water and 250 \(\mu\)L of the extract were thoroughly mixed. After 30 min of incubation at room temperature, the absorbance was measured at 450 nm. The results are presented in mg Trolox:g\({}^{-1}\) of nalewka. Total polyphenol content was determined using the Folin-Ciocalteu (F-C) method [6]. Shortly, 0.15 mL of the studied sample, 0.15 mL of tenfold diluted Folin-Ciocalteu reagent, 1.35 mL of 0.01 M sodium carbonate aqueous solution, and 1.35 mL of water were added and mixed. The spectrophotometric measurement was carried out at 765 nm. The time of incubation was 15 min. The results were expressed as gallic acid equivalents (GA) in mg GA:g\({}^{-1}\) of nalewka. Three independent measurements were made. Total anthocyanins content (TAC) was estimated using the modified method proposed by [PERSON] et al. [46]. The absorbance of fruit nalewka diluted in buffers at 1.0 pH (hydrochloric acid-potassium chloride) and 4.5 pH (acetic acid-sodium acetate) was measured at 510 as well as 700 nm. Results were expressed as cyjanidin-3-glucoside equivalents (mg Cy-3-Glu:mL\({}^{-1}\) of nalewka). Three independent measurements were made. Total tannin content (TTC) was carried out using a methodology described by [PERSON] et al. [42]. Briefly, two samples of each nalewka containing 200 \(\mu\)L of 10-fold diluted nalewka, 300 \(\mu\)L of concentrated HCl, and 100 \(\mu\)L of distilled water were prepared. The first sample was incubated at 100 \({}^{\circ}\)C for 30 min, while the second sample, to which 50 \(\mu\)L of 96%(\(v/v\)) ethanol was added, was left at room temperature.