## 3 Results and Discussion
### Screening of NADES for Phytochemical Recovery Across Diverse Plant Matrices
This method produced 3.545 mg/mL of total carotenoids, which includes 3.341 mg/mL of \(\beta\)-carotene and 0.049 mg/mL of lutein, surpassing acetone in terms of efficiency [28]. Additionally, the menthol-eucalypt and lauric acid-octanoic acid HDESs obtained by [PERSON] et al. [29] demonstrated significantly higher total carotenoid content in ultrasound-assisted extraction compared to conventional solvents such as hexane, acetonitrile, methanol, and ethanol. According to the examples given above, hydrophobic deep eutectic solvents (HDESs) exhibit high affinity to non-polar carotenoids (such as \(\beta\)-carotene and lutein) because of their hydrophobic characteristics and components like fatty acids or terpenoids. Moreover, HDESs serve as a protective matrix, stabilizing carotenoids against oxidative degradation during extraction and storage. Additionally, they can switch between hydrophobic and hydrophilic states, simplifying carotenoid recovery and solvent reuse while minimizing energy and resource consumption [27; 28; 29]. The next group of bioactive compounds, anthocyanins, was also tested in this study. The selection of solvents significantly influenced anthocyanin recovery (expressed as mg of cyanidin-3-glucoside/g d.m.) from chokeberry pomace and red onion, as shown in Figure 3. The mixture of ethanol and hydrochloric acid demonstrated exceptional efficacy, yielding the highest anthocyanin content in both matrices: 0.212 mg/g for chokeberry pomace and 0.012 mg/g for red onion. For chokeberry pomace, NADES4 was identified as the second most effective solvent (0.104 mg/g), surpassing conventional solvents such as water (0.049 mg/g) and ethanol (0.050 mg/g). In contrast, NADES5 (0.032 mg/g) and NADES1 (0.034 mg/g) showed the lowest extraction capacities. In red onion, the most effective solvents were water (0.009 mg/g) and EtOH-HCl (0.012 mg/g). Most NADES formulations, such as NADES2 (0.005 mg/g) and NADES3 (0.004 mg/g), demonstrated limited effectiveness. Ethanol used alone (0.004 mg/g) also showed poor results, underscoring the essential role of HCl in improving anthocyanin extraction. As noted in a different study, solvent acidification is essential for maintaining the structural integrity of anthocyanins, as the flavylium cation--responsible for their bright red color--only exists in acidic environments (pH < 3), which ensures both color intensity and stability [4]. Similar to other compound groups, the use of green solvents, particularly NADESs, enhances the extraction efficiency of anthocyanins, as well as their stability, bioavailability, and antioxidant activity. According to the review conducted by [PERSON] et al. [30], the eutectic mixture of choline chloride and oxalic acid is identified as the most effective solvent for extracting anthocyanins. The authors also suggest that organic acid-based eutectic solvents outperform other solvents in extracting polar anthocyanins. In this study, one of the NADES tested comprised citric acid and choline chloride, yielding results similar  
Figure 3: The influence of the solvent selection on the anthocyanin content (mg of cyanidin-3-glucoside/g d.m.) in (**a**) chokeberry pomace and (**b**) red onion. Error bars represent the standard deviation (SD) of three independent measurements. The values with the same lowercase letters (a–c) do not differ significantly (\(\alpha=0.05\)). to ethanol, although still lower than those of acidified ethanol and NADES based on choline chloride combined with glycerol or urea. [PERSON] et al. [31] also utilized a choline chloride-glycerol NADES to extract anthocyanins from borage (_Echium amoenum_) flowers. The results showed that this mixture was much more effective than conventional solvents like water, methanol, or ethanol. It achieved the highest levels of total anthocyanin, total phenolic, total flavonoid content, and antioxidant activity. Intriguingly, [PERSON] and [PERSON] [32] found that using choline chloride-urea NADES to extract blackberry anthocyanins did not result in detectable anthocyanins in the final extract.