## 2 Materials and Methods
### Analytical Methods
#### 2.3.7. Bioactive Compounds and Antioxidant Activity  
The determination of vitamin C content was carried out through ultra-performance liquid chromatography (UPLC) with the use of the UPLC-PDA system (WATERS Acquity H-Class, Milford, MA, USA) [35]. Following the procedure, 10 mL of cooled extraction reagent containing 3% metaphosphoric acid and 8% acetic acid was added to around 0.3 g of dried material. Then, the solution was stirred with a vortex for 5 min, centrifuged for 2 min at 5 \({}^{\circ}\)C, filtered through 0.2 \(\upmu\)m GHP syringe filters (Acroddisc, Pall Corporation, Port Washington, NY, USA), and diluted twice with eluent (Milli-Q water with 0.1% formic acid). In the next step, separation on a Waters HSS T3 chromatographic column (100 mm \(\times\) 2.1 mm, 1.8 \(\upmu\)m; Waters, Ireland) for 5 min at 35 \({}^{\circ}\)C with a mobile phase flow rate of 0.25 mL/min was conducted. The quantitative content of ascorbic acid was accomplished by analysis of the spectrum at 245 nm and the usage of the calibration curve for the L(-) ascorbic acid standard. The analysis was performed twice for each sample. Total Polyphenol Content (TPC)  
The determination of TPC was made via the spectroscopic method, which used a color reaction of the analyte with the Folin-Ciocalteu (F-C) reagent [36]. In order to prepare the material for the analysis, the dried fruits were ground in an analytical mill (IKA A11 basic; IKA-Werke GmbH, Staufen, Germany). The extraction was conducted for 12 h at 20 \({}^{\circ}\)C on a shaker (Multi Reax, Heidolph Instruments, Schwabac, Germany) with the use of a mixture of 80% ethyl alcohol and 0.1 M hydrochloric acid (85:15, \(v/v\)). Then, the solutions underwent centrifugation in a laboratory centrifuge (MegaStar 600, VWR, Leuven, Belgium) for 2 min at 4350 rpm. For each sample, the extraction procedure was performed in duplicate. The extracts of 10 \(\mu\)L were diluted twice with distilled water and placed in a 96-well plate. The 5-fold-diluted Folin-Ciocalteu reagent of 40 \(\mu\)L was added to the solutions, followed by supersaturated calcium carbonate of 250 \(\mu\)L after 3 min. Then, the reactions were carried out for 1 h at room temperature, protected from light. Absorbance at a wavelength of 750 nm was measured for each sample against a reagent blank on a multiplate spectrophotometer (Multiskan Sky, Thermo Electron Co., Waltham, MA, USA). The quantitative content of polyphenols was assessed with reference to a calibration curve prepared for chlorogenic acid in the concentration range of 0 to 100 \(\mu\)g/mL. The analysis was performed in two repetitions. Total Flavonoid Content (TFC)  
The aluminum (III) chloride method was employed to assess the total flavonoid content [37]. Initially, 20 \(\mu\)L of the extract was combined with 80 \(\mu\)L of distilled water and mixed with 10 \(\mu\)L of 5% (\(w/v\)) NaNO\({}_{2}\) solution. After 5 min, 10 \(\mu\)L of 10% (\(w/v\)) AlCl\({}_{3}\) was added and mixed. Following an additional 6 min, 40 \(\mu\)L of 1 M NaOH solution was introduced and thoroughly mixed. After 20 min, the absorbance was recorded at 510 nm. The flavonoid concentration was determined using a calibration curve for quercetin within the range of 0-500 \(\mu\)g/mL. All measurements were performed in duplicate. Antioxidant Activity (DPPH Radical)  
The evaluation of antioxidant activity was carried out using a spectrophotometric method that quantified the ability of the sample to neutralize the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical [37]. The initial DPPH solution was prepared by dissolving 0.025 g of 2,2-diphenyl-1-picrylhydrazyl in 100 mL of 99% methanol. To allow the formation of radicals, the solution was stored at 4 \({}^{\circ}\)C in the dark for at least 24 h. Before the analysis, the working solution was prepared by diluting 9 mL of the stock solution with 80% ethanol to obtain an absorbance of 0.700 \(\pm\) 0.020 at 515 nm.