## 4 Conclusions  
Technological processing, harvest year, and natural variability influence the chemical composition of currant juices and commercial currant products. The greatest differences between BC and RC juices were in ascorbic acid content (1567 \(\pm\) 426 mg/kg in BC and 261 \(\pm\) 98 mg/kg in RC), citric acid content (34.6 \(\pm\) 6.4 g/kg in BC and 23.2 \(\pm\) 7.0 g/kg in RC), and the anthocyanin profile. Significant differences were observed for BC juices in the content of sucrose and anthocyanins (Dp-3-glu, Cy-3-glu, and Dp-3-rut) within the different processes (enzyme/non-enzyme juice) and the content of fructose and ascorbic acid within the harvest year (2020/2021). The fructose content of black and red currants was higher in 2021, while the ascorbic acid content was lower in that year than in 2020. For RC, there were differences in the fructose content within the harvest year. The chemical composition of commercial products is highly variable (especially for concentrates and nects), which is influenced not only by the choice of variety but also by the production process and recipe. Homogenates have a higher ash and mineral content than juices due to the peel content of the product. Concentrates and nects have a lower ascorbic acid content and a highly variable anthocyanin content than juices, which is probably due to the choice of raw material, the production process (increased temperature and pH, access to oxygen) and storage time. The data obtained could be useful in the compositional characterisation of authentic black and red currant varieties and selected commercial currant products for breeders, scientists, or specialised food industries.  
Figure 5: PCA biplot analysis of the selected commercial products (homogenates (BC/RC), concentrates, and nects, 19) and chemical compounds (17)—soluble solids (Rf), sucrose (Sach), glucose (Glc), fructose (Fru), ratio of Glc/Fru, malic acid (MA), citric acid (CA), D-isocitric acid (ICA), ratio of CA/ICA, titratable acidity (TA), formed number (FN), ash, phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), and ascorbic acid (AA).  
**Author Contributions:** Conceptualisation, T.P. and H.C.; methodology, T.P., A.T. and H.C.; software, T.P. and F.B.; validation, T.P., F.B. and H.C.; formal analysis, T.P., N.K.B., M.H., F.B. and A.T.; investigation, T.P., N.K.B. and M.H.; resources, T.P., M.H. and H.C.; data curation, T.P.; writing--original draft preparation, T.P.; writing--review and editing, N.K.B., F.B. and H.C.; visualisation, T.P.; supervision, T.P. and H.C.; project administration, T.P.; funding acquisition, T.P. and H.C. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the University of Chemistry and Technology, Prague, Czech Republic--grant No. A1_FPBT_2024_008.  
**Institutional Review Board Statement:** Not applicable.  
**Infrared Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy reasons.  
**Acknowledgments:** We would like to thank AB Enzymes GmbH (Darmstadt, Germany) for providing the enzyme preparation.  
**Conflicts of Interest:** The authors declare no conflicts of interest.