Green extraction of polyphenols from Berberis vulgaris using NADES: process optimization and extract characterization

Berberis vulgaris is a valuable source of bioactive polyphenols known for their antioxidant and antimicrobial properties. In this study, a green extraction method using the choline chloride: lactic acid: water (ChCl:LA:H₂O) natural deep eutectic solvent (NADES) was developed to recover polyphenolic compounds from Berberis fruits. Using a Box-Behnken design, the optimal extraction conditions were determined to be 65 °C, a 5% water content, and a 0.055 liquid-to-solid ratio. These conditions resulted in a total phenolic content of 98.51 mg GAE/g and a DPPH radical scavenging activity of 89.91%. The temperature of 60 °C is selected as the final extraction temperature for future studies to ensure thermal stability and minimize degradation. Throughout at 4 °C the extract remained stable, maintaining high TPC and DPPH over time. Furthermore, the extract reduced browning in fresh-cut apples, maintaining the visual appearance for seven days. Moreover, the extract exhibited strong antibacterial activity against Gram-positive and Gram-negative bacteria. Therefore, this study demonstrates that NADES-based solvents, a green approach, provide an efficient, sustainable, and thermally stable method for the extraction of bioactive compounds from Berberis fruits, appropriate for food preservation and biodegradable active packaging applications.