## 4 Discussion  
### Basic Chemical Composition  
It is worthy to note that there is no literature data concerning the basic chemical composition of currant leaves harvested in various time periods. Currently, researchers are more focused on the concentration of bioactives and antioxidant activity in blackcurrant leaves [19; 20]. However, our study was focused on three types of currant leaf harvested in different months during the two-year period. It was found that the leaves of the redcurrant had the highest content of dry matter out of the examined currants. The exception was the May harvests in both years, when the blackcurrant leaves had a dry matter content the same as or higher than the redcurrant leaves. It was also found that the dry matter content in all varieties of currant leaf increased at subsequent harvest times. Although there is no available data in the literature on the dry matter content in currant leaves there are studies carried out on other plants, which confirmed our findings. [PERSON] et al. [21] have indicated an increase in the dry matter content in plant leaves during their life cycle. A similar tendency was also observed by [PERSON] et al. [22] in plant leaves growing in Northeast India. In our study, the highest protein content was found in whitecurrant leaves. Only in the second and third harvest from 2019 was a similar amount of protein detected in the dry matter of the leaves of other currant species. Once again, no literature information was found on the protein content of currant leaves, however, in blackcurrant fruit, protein concentration was 1.4 g/100 g of fresh matter (7.77 g/100 g DM) [1]. Our results indicated that leaves of various types of currant have significantly higher content of fat than in the fruit (0.77 g/100 g dm) as reported earlier by [PERSON] [1]. [PERSON] [9] has shown that fat in blackcurrant leaves is rich in fatty acids such as \(\alpha\)-linolenic, cis/7,10,13-hexadecatrienoic, stearidine and \(\gamma\)-linolenic, as well as phosphatidylcholine and phosphatidylglycerol. It is also known that blackcurrant seeds are rich in unsaturated fatty acids in the range of 14% to 23% per dry matter [23]. The ash content in all studied currants increased during the shrub's growing period in both 2018 and 2019 (Table 1). Many researchers have reported that the leaves of currant shrubs are a rich source of calcium, potassium and magnesium, but their content depends on the various factors including the time of harvesting of the leaves [7; 24; 25]. In addition, [PERSON] et al. [7] have reported that currant leaves in mid June had the highest content of calcium, magnesium, iron, manganese, aluminum, chromium and boron. A similar relationship between the harvest time and the content of nitrogen, magnesium, calcium, manganese and copper was demonstrated by [PERSON] and [PERSON] [26] in blueberry leaves. According to [PERSON] et al. [27] and [PERSON] et al. [25], meteorological conditions and the intensity of soil fertilization affect the content of minerals in the plant. However, they can affect their amount in various ways, depending on the minerals. It is noteworthy to indicate that currant shrubs from which the research material was collected were not fertilized. Therefore, a significantly higher amount of ash in the dry matter of the currant leaves collected in 2019 could result from weather conditions. Based on information found in the Bulletin of the State Hydrological and Meteorological Service in Poland [28], the year 2019 was warmer and drier than the previous year [29].