## 3 Results and Discussion  
### Chemical Composition of Black and Red Currant Juices  
The effect of different processes (enzymatic (E) and without enzymatic (WE) juice pressing) and harvest year (2020 and 2021) on the chemical composition of the currant juices was studied on a laboratory scale, using berries of black and red currant. The analysis was based on 20 selected quality parameters (e.g., sugars, organic acids, mineral substances, and anthocyanin content). Of the four groups of currant juices, the average juice yield was highest for RC with enzyme addition (79%), followed by RC without enzyme addition (76%) and BC with/without enzyme addition (approximately 70%). No effect (\(p\) > 0.05) was observed for the yield with/without enzyme addition. The juice yields for the individual currant samples are shown in Table 1. For varieties from the same farmers, yields were similar over the two years. Only the Red Hube variety had a 3% higher yield in 2021. According to the literature sources, yields for black currant juice with enzyme addition range from 66 to 79% and from 58 to 72% without enzyme addition, and those for red currant juice with enzyme addition and ultrasound effect range from 86 to 88%. The reason for the low yield of juice could be attributed to the high pectin content of the berries [4,8,10]. The chemical compositions (f.w.) of BC and RC juices are presented in Table 3. It should be noted that the values for sorbitol are not shown in Table 3 and Table 5 as it was not detected in all samples. The statistical difference (\(p<0.01\)) between black current (BC) samples with enzyme addition (E) and without enzyme addition (WE) is only in sucrose content (at 0.2-1.8 g/kg E vs. \(<\)0.1 g/kg WE). The cut-off values for BC E/WE were for the FN (\(p=0.061\)) and magnesium content (\(p=0.053\)). The effect of the harvest year (2020-2021) of BC was observed (\(p<0.05\)) for fructose and ascorbic acid content. The average ascorbic acid content was higher in 2020 (1756 mg/kg) than in 2021 (1377 mg/kg). In contrast, the average fructose content was lower in 2020 (45.6 g/kg) than in 2021 (53.1 g/kg). The cut-off values for BC 2020/2021 were for glucose (\(p=0.056\)). The same varieties (Titania, Ojebyn, Red Hube) had a higher sugar content in 2021 than in 2020. The Red Hube variant even had almost double the glucose and fructose content (Glc: 29.6 g/kg versus 55.5 g/kg and Fru: 35.0 g/kg versus 66.8 g/kg). This may be due to climatic conditions or a higher maturity at harvest. There were no significant differences (\(p>0.05\)) in the chemical composition of RC juices depending on harvest year or different processes (E/WE). The cut-off values for RC 2020/2021 were for fructose (\(p=0.058\)). In contrast, minimal differences (\(p>0.9\)) were observed in malic acid, D-isocitric acid, phosphorus, magnesium, and calcium content. The greatest differences (\(p<0.001\)) between black and red currant were in the content of ascorbic acid (1567 \(\pm\) 436 mg/kg in BC and 261 \(\pm\) 101 mg/kg in RC), titratable acidity (37.9 \(\pm\) 4.2 g/kg in BC and 25.5 \(\pm\) 3.8 g/kg in RC), soluble solids (16.1 \(\pm\) 1.8\({}^{\circ}\)Brix in BC and 12.3 \(\pm\) 2.3\({}^{\circ}\)Brix in RC), and citric acid (34.6 \(\pm\) 6.4 g/kg in BC and 23.2 \(\pm\) 7.0 g/kg in RC) and in the anthocyanin profile (Tables 3 and 4 and Figure 4). The Code of Practice (CoP) reference guidelines are commonly used in European countries to verify the quality of black currant juices. The Association of the Fruits and Vegetable juice and Nectar Industry of the European Union (AIJN), an organisation dedicated to standardising quality rules and assessing the authenticity of fruit juices, established the Code of Practice [28]. However, some of our results (see Table 3), such as titratable acidity values, fall outside this range, as do phosphorus, formed number, and citric acid for WE samples and ash for E samples. Similar TA results were obtained by the authors [PERSON] and [PERSON] [10] during the evaluation of black and red currant.