## 3 Results and Discussion
### Color Parameters and Coloring Strength of Anthocyanin Extracts
Blue bars—material/solvent ratio 1:20, red bars—material/solvent ratio 1:7; (**a**) extracts obtained with water–ethanol (50/50 \(v/v\)) solvent; (**b**) extracts obtained with water–citric acid solvent. The values with different letters within the same color are significantly different (\(p<0.05\)). Figure 2: Lightness (L*) (**a,b**) of the extracts. Blue bars—material/solvent ratio 1:20, red bars—material/solvent ratio 1:7; (**a**) extracts obtained with water–ethanol (50/50 \(v/v\)) solvent; (**b**) extracts obtained with water–citric acid solvent. The values with different letters within the same color are significantly different (\(p<0.05\)). Studies by other researchers have shown that UAE parameters and solvent characteristics have a strong influence on the color of pomace extracts. [PERSON] et al. [20] reported that as pH increased, the values of C* and h\({}^{\circ}\) also increased. Acidified water extracts at low pH (1.5-2.0) had lower purity and darker color. The extraction process at 30 \({}^{\circ}\)C was better than that at 50 \({}^{\circ}\)C in terms of the coloring properties of the extracts, as higher values of a* were found to result in higher chroma values [14]. This is in line with the results of our research. In another study, the longer exposure time of pomace to ultrasound during extraction led to higher L* values of the extracts [21]. All samples obtained from UAE had a chroma between 35.9 and 42.7, meaning that the grape pomace extracts had 2-3 times better color saturation than our blackcurrant extracts. However, completely different extraction parameters and materials have been used. It should be noted that the varieties of a given plant influence the profile of anthocyanins in the fruit, which consequently translates into the composition of these substances in the extracts and their coloring properties. This was demonstrated by [PERSON] et al. [35] on the example of extracts obtained from different grape cultivars. E1% coloring strength is one of the main characteristics of colorants used in food. Food manufacturers are interested not only in the color parameters of the extract or concentrate but also in the level of coloring power of the product. E1% determines the use of the right amount of coloring to achieve the desired color properties. The amount of pomace in the extraction solution significantly (\(p<0.05\)) influenced the coloring strength of the extracts. E1% values were 2-3 times higher for a material-to-solvent ratio of 1:7 than for 1:20 (Figure 5). The type of solvent also significantly (\(p<0.05\)) affected the coloring strength. Extracts obtained with water-citric acid solvent had higher and more uniform absorbance at \(\lambda=520\) nm. However, the highest absorbance was measured in two water-ethanol extracts obtained after 15 and 30 min of extraction at 35 \({}^{\circ}\)C. These were the extracts with the highest anthocyanin content determined. In general, the highest E1% values were obtained at 35 \({}^{\circ}\)C in our experiment, but as the extraction time increased, the values decreased, suggesting that the extraction process should not be extended to 60 min. This phenomenon was most evident in the water-ethanol extracts. The industry uses natural colorings when they have strong coloring power. Rather, our extracts should be considered strong dyes, especially since the E1% parameter was measured before the targeted concentration and purification processes. Figure 4: Hue (h\({}^{\circ}\)) (**a,b**) of the extracts. Blue bars—material/solvent ratio 1:20, red bars—material/solvent ratio 1:7; (**a**) extracts obtained with water–ethanol (50/50 \(v/v\)) solvent; (**b**) extracts obtained with water–citric acid solvent. The values with different letters within the same color are significantly different (\(p<0.05\)).