## 4 Discussion
The variation in results could also result from the different storage time of currant fruits, during which the polyphenol content decreases [45; 46; 47]. The lower content of polyphenols in currant preparations may have been due to the fact that the composition of these products is not limited to currant fruits. They could be supplemented with ingredients enriching sensory values or other fruits with a lower or higher content of polyphenols in relation to currants. A different amount of polyphenols could also be caused by the sensitivity of these compounds to technological treatment [48]. In the found publications, the content of polyphenols for black, red and white currants was much lower than the results presented in the work. The polyphenol content for black currants was indicated by [PERSON] [49] and [PERSON] et al. [50] and was respectively 560 mg CGA/100 g DM and 888.5 mg CGA/100 g FM. These authors also reported a value for red currants of 501.6 mg CGA/100 g FM. [PERSON] et al. [51] were investigating six types of forest fruit in this study regarding the content of some bioactive compounds. The parameters were determined in a fresh state and after freezing at \(-18~{}^{\circ}\)C and \(-80~{}^{\circ}\)C, respectively. Total phenolic content ranged from 442 in white currants, 937.77 in red currants to 2.385 mg GAE/100g in black currants. In every case, the frozen fruits had a higher total polyphenol content than the fresh ones. [PERSON] et al. [52] assessed the total phenolic, flavonoid, and anthocyanin content and the antioxidant activity of five commonly consumed commercial berry jams (blueberry (_Vaccinium myrtillus_), blackberry (_Rubus fruticosus_) and black currant (_Ribes nigrun_) mixture, black currant (_Ribes nigrun_), cranberry (_Vaccinium mucroaron_) and raspberry (_Rubus ideas_)) collected from the market. It is understood that the process of making jam, which involves heat treatment, significantly reduces polyphenol content in fruits. The polyphenol content for black currants jam was around 473.9 1 GAE mg/100g FW [52]. Based on the results of our study and those of other authors, black currant fruit is one of the richer sources of polyphenols, and its antioxidant activity is higher than in many other fruits such as apples, pears and even some berries. According to [PERSON] et al. [53], black chokeberry fruit (1756 mg/100 g fresh weight), elderberry fruit (1359 mg/100 g fresh weight), lowbush blueberry fruit (836 mg/100 g fresh weight) and black currant fruit (758 mg/100 g fresh weight) had the highest content of polyphenolic compounds. Apples (136 mg/100 g fresh weight), plums (377 mg/100 g fresh weight) or pears (17 mg/100 g fresh weight) had a lower content of polyphenolic compounds compared to black currants. [PERSON] and [PERSON] et al. [54] showed that the fruits of apple, chokeberry and cranberry grown in Poland contained 9457.59, 7806.51 and 11,095.46 mg/100 g DM of polyphenolic compounds, respectively. [PERSON] et al. [25] found that sweet cherry fruits contained polyphenolic compounds in the range of 1744.62-4045.32 mg/100 g DM of chlorogenic acid. These authors also found that it depends not only on the variety but also on the country of origin. [PERSON] et al. [53] reported that the content of polyphenolic compounds in red currants, was 43 mg/100 g fresh weight. However, although red currants contain about 10 times less anthocyanins (10-20 mg/100 g) and 2-3 times less polyphenols (190-320 mg/100 g) than black currants, their superoxide radical scavenging capacity and in vitro xanthine oxidase inhibition activity are almost as high as in black currant extracts as was reported by [PERSON] et al. [45]. In our study we have found that red currants fruit had the highest antioxidant activity measured with ABTS and DPPH method. Probably other bioactive hydrophilicity and lipophilicity substances could give these results. The antioxidant content of currant fruits is influenced by the variety, storage or degree of ripeness of the fruit [7; 12; 55].