Application of Natural Deep Eutectic Solvents (NADES) for the Extraction of Floral Phenolics and Anthocyanin Degradation Kinetics

Natural deep eutectic solvents (NADES) are promising eco-friendly alternatives to traditional solvents for extracting phenolic compounds from plant materials. However, their effectiveness depends on both solvent composition and the botanical matrix. This study examined water, ethanol, and choline chloride–urea (CCU) and choline chloride–glycerol (CCG) systems containing 30% or 60% NADES for the extraction of anthocyanins, total phenolic content, total flavonoid content, and antioxidant capacity (DPPH and ABTS) from cornflower, safflower, and pomegranate flowers. Pomegranate flowers exhibited the highest levels of anthocyanins, total phenolics, and antioxidants, while safflower showed the highest total flavonoid content. Overall, the 60% NADES formulations delivered the best extraction results, whereas ethanol had the lowest overall efficiency. A combined heatmap analyzing all responses identified 60% CCU and 60% CCG as the most effective solvents across all tested materials. Anthocyanin stability in pomegranate flower extracts was further evaluated over 8 weeks at 4 and 20 °C. First-order kinetic analysis revealed that ethanol and 60% CCG maintained the highest anthocyanin stability, whereas 60% CCU exhibited the lowest stability, especially at 20 °C. These findings support the use of NADES as efficient solvents for floral bioactives, while indicating that the highest extraction yield does not necessarily correlate with the best storage stability.