## 3 Results and Discussion
### Integrated Evaluation of Instrumental and Sensory Data Using PCA Analysis  
To better visualize the differences between samples (black vs. red vs. white cultivars and the 2020 vs. 2021 seasons) and the relationships between instrumental (volatile composition) and sensory characteristics, all acquired results were subjected to PCA. PCAwas performed using the averaged ratings (\(n=20\)) of all sensory characteristics and the averaged peak area (\(n=2\)) of identified chemical groups of volatile compounds. The results for the first two principal components (PCs) are shown in Figure 2. The first three PCs cumulatively explained more than 70% of the total dataset variability. Figure 2a demonstrates a distinct separation between samples, although seasonal variability (2020 vs. 2021) is less prominent. While individual cultivars cluster closely, they remain clearly differentiated. Principal component 2 (PC2) effectively distinguishes between the two years for all studied cultivars. The influence of season (2020 vs. 2021) on the aroma profile of currants is further illustrated in Supplementary Material Figure S1  
Figure 2: Projection of samples (current cultivars) (**a**) and of the variables (groups of volatile compounds and sensory properties) (**b**) on factor plane obtained with first two PCs. For sample labeling, see Section 2. (based on peak area). This figure also highlights the significantly higher total content of compounds, particularly terpenoids, in black currants. Limited research exists on the effect of season on aroma compounds in currants, and the impact of season on sensory properties, has not been extensively investigated. [PERSON] et al. [7] and [PERSON] et al. [15; 19] reported significant environmental effects, with temperature and radiation identified as key factors. Conversely, [PERSON] et al. [6; 26] observed consistent levels of selected compounds in black currants across two years. In this study, Kruskal-Wallis and ANOVA analyses revealed significant differences (\(p\leq 0.05\)), primarily in flavor and odor (see Table 1). Notably, the previously identified best cultivars ('Victoria', 'Rubigo', and 'Demon') did not exhibit significant differences in sensory properties, indicating their stability and resilience to varying climatic conditions. However, almost all cultivars showed significant differences in aroma composition, especially in alcohol content (see Table S3), confirming the substantial influence of environmental factors. Pinpointing specific effects remains challenging due to compound-specific variations. Climatic conditions for the harvest years (2020/2021) are summarized in Supplementary Material Figure S2 for reference. Although 2020 was generally warmer than 2021 in the Czech Republic, temperatures during the current ripening period (typically June to August) were comparable, with a maximum difference of approximately 3 \({}^{\circ}\)C.  
The effect of currant type (red/white/black) is evident (see Figure 2a), with two distinct clusters. All black currant cultivars are located in the left part of the plot, correlating negatively with PC1. The second cluster, correlating positively with PC1, includes red and white cultivars, indicating their similarity in composition and sensory properties. The red and white cultivar clusters partially overlap, but separation can be observed along PC2. Most red cultivars are located in the upper part, correlating positively with PC2, except for 'Rubigo', which was sensorially evaluated as the most acceptable and is, thus, clearly separated from other red cultivars. White cultivars are at the bottom, correlating with flavor, firmness, and overall acceptability. 'Jantar' is the only exception, being considered the least acceptable of the white cultivars. This suggests that white currants were sensorially preferred over red currants, likely due to their sweeter taste, better flavor, and texture, particularly their firmness/crispiness.