## 3 Results and Discussion
### Color Parameters and Coloring Strength of Anthocyanin Extracts  
The value of the lightness (L*) for extracts prepared with the water-ethanol solvent ranged from 29.1 to 31.3 (1:20) and from 11.3 to 18.0 (1:7). On the other hand, the L* value for extracts prepared using the water-citric acid was 28.5-30.9 (1:20) and 13.9-16.9 (1:7). The ratio of pomace to solvent had a significant effect (_p_ < 0.05) on this parameter measured in the anthocyanin extracts obtained (Figure 2). As can be seen in Figure 2a,b, changing the ratio from 1:20 to 1:7 made the extracts about two times darker, regardless of the solvent used. The extraction time had no statistical significance (_p_ > 0.05) on the L* parameter. Three temperature values were tested, and the darkest extracts were obtained at 35 \({}^{\circ}\)C and 45 \({}^{\circ}\)C. As might be expected, the L* of the extracts was inversely proportional to the anthocyanin. The higher the anthocyanin content, the lower the L* and the darker the color of the extracts. Pearson's correlation coefficient between the measured values was \(-\)0.988 and \(-\)0.994 for water-ethanol and water-citric acid extracts, respectively. The chroma (C*) parameter on the CIE L*a*b* scale determines color saturation, takes values from 0 (the center of the coordinate system), and increases along the radius of the circle. The ratio of pomace to solvent had a significant effect (_p_ < 0.05) on the C* parameter of the extracts (Figure 3a,b). Extracts obtained with a ratio of 1:20 had higher chroma values. The type of solvent used also had an impact. Water-ethanol solvent had higher C* values. The extracts with high C* values were recognized as clearer, brighter or more brilliant, while dull or dark pastel colors had extracts with a low C* value. The extraction time significantly (_p_ < 0.05) influenced the color saturation of the extracts. In the case of the water-ethanol solvent, samples had the most saturated color after 15 min, while the water-citric acid samples reached the highest saturation after 60 min of extraction. The highest values of C* were achieved by extracts obtained at a process temperature of 25 \({}^{\circ}\)C and 35 \({}^{\circ}\)C. Correlation analysis showed a strong relationship between anthocyanin content and color saturation (\(-\)0.991 and \(-\)0.995 for water-ethanol and water-citric acid extracts, respectively). The higher the anthocyanin concentration, the duller/more pastel the color of the extracts. The parameter h\({}^{\circ}\) defines the hue of the color. It is defined by degrees of the angle starting from the positive side of the a*-axis and proceeding counterclockwise on a circle, and forming the following ranges: from 0\({}^{\circ}\) red, through 90\({}^{\circ}\) yellow, 180\({}^{\circ}\) green, 270\({}^{\circ}\) blue to 360\({}^{\circ}\) red. The hue h\({}^{\circ}\) of the water-ethanol extracts ranged from 37.1 to 38.7 (1:20) and from 23.9 to 30.4 (1:7). However, the h\({}^{\circ}\) value of water-citric acid extracts was 37.9-39.4 (1:20) and 26.9-28.7 (1:7). Therefore, all extracts were in the hue zone of the red color. The structure of anthocyanins strongly depends on the pH of the matrix, and all extracts had a pH in the range of 1.5-2.6, where anthocyanins are present in the form of red flavylium cations. In addition, the value of the parameter h\({}^{\circ}\) was affected (\(p<0.05\)) by the ratio of pomace to solvent (Figure 4a,b). Extracts obtained with a ratio of 1:7 had a more intense red hue due to the higher anthocyanin content. Statistical tests showed that if the extraction time and temperature increased, the hue value was also higher (\(p<0.05\)). For this color parameter, [PERSON]'s correlation test also showed a very strong relationship with the anthocyanin content of the extracts (\(-0.997\) and \(-0.993\) for water-ethanol and water-citric acid extracts, respectively). Figure 3: Chroma (C*) (**a,b**) of the extracts.