## 3 Results and Discussion
### Determination of Quercetin and Gallic Acid  
The quercetin content was 0.465 \(\pm\) 0.058 mg/100 g fresh weight, while the gallic acid content was 88.25 \(\pm\) 0.478 mg/100 g fresh weight. The values for quercetin content from the literature are quite variable. Still, [PERSON] et al. (2020) obtained similar values [38], as in their case, the concentration of quercetin is 2.96 \(\pm\) 0.05 mg/100 g dry weight, while [PERSON] et al. (2005) obtained 0.63 \(\pm\) 0.01 mg/100 g fresh weight [27]. This can be explained by the result obtained by [PERSON] et al. that higher precipitation and lower temperature led to an increase in the quercetin and gallic acid content of blackberries [38]. For gallic acid, our results were relatively close to the values obtained by [PERSON] et al. (2010): 113.13 mg/100 g fresh weight [45]. Theoretical Study of the Effect of Acetonitrile-Water Concentration on Anthocyanin Extraction Based on Hansen Solubility Parameters  
Theoretical tools and models are often used to predict the solubility of bioactive molecules. These tools are phase solubility studies, quantitative structure-property relationships, calculation of Hansen solubility parameters by the group contribution method, the Flory-Huggins interaction parameter, the real solvent conductive screening model (COSMO-RS), and the COSMO segmental activity coefficient model. These models can be applied to the extraction process of anthocyanins to predict which solvent is most effective against which molecule. However, these models have varying degrees of complexity, and there is no literature available to evaluate which model would be preferable for this purpose. The Hansen solubility parameters are the most suitable for finding the most optimal organic solvent-water mixture ratio. Finding the most optimal ratio of organic solvent to water is important because it gives a higher dissolution rate. Using this mixture will shorten the analysis time, and the amount of anthocyanins extracted will be as high as possible, giving the closest value to the true antioxidant content. Due to the good solubility, the amount of solvent used can also be significantly reduced. The difference in solvent efficiency could be explained by the terms of [PERSON] and Hildebrand solubility parameters of the solvents and solutes, as summarized in Table 5. Cyanidin and cyanidin-3-O-glucose were chosen for solutes because they are the dominant anthocyanins in blackberry [46]. Both acetone and acetonitrile are polar solvents (Table 5), and their intermolecular hydrogen bond forming ability is low. Acetonitrile has the highest polar Hansen parameter among the used solvents and, therefore, is better able to extract more polar active compounds, some of which may have strong antioxidant activity, although, more precise correlations could be made only when the individual components in the extracts are known. In the case of aliphatic alcohols, strong hydrogen bonds are formed between the solvent molecules (polar protic solvents), making them suitable solvents, but in the case of alcohols, solubility decreases with increasing the carbon chain length, which explains why methanol is a better solvent than ethanol [49]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Solvents and Solutes**} & \multicolumn{2}{c}{**Hansen Parameters**} & \multicolumn{2}{c}{**Hildebrand Parameter**} \\  & **\(\mathbf{\tilde{z}_{D}}\) (Dispersive)** & \(\mathbf{\tilde{z}_{P}}\) (Polar) & \(\mathbf{\tilde{z}_{H}}\) (H-Bond) & \(\mathbf{\tilde{z}}\) \\  & **MPa\({}^{\mathbf{0.5}}\)** & **MPa\({}^{\mathbf{0.5}}\)** & **MPa\({}^{\mathbf{0.5}}\)** & **MPa\({}^{\mathbf{0.5}}\)** \\ \hline Acetone & 15.50 & 10.40 & 7.00 & 19.93 \\ Acetonitrile & 15.30 & 18.00 & 6.10 & 24.39 \\ Ethanol & 15.80 & 8.80 & 19.40 & 26.52 \\ Methanol & 15.10 & 12.30 & 22.30 & 29.60 \\ Water & 15.60 & 16.00 & 42.30 & 47.80 \\ Cyanidin & 27.15 & 18.01 & 27.06 & 42.35 \\ Cyanidin-3-O-glucose & 25.70 & 19.48 & 28.08 & 42.76 \\ \hline \hline \end{tabular}
\end{table}