Advances in the extraction of polyphenols using natural deep eutectic solvents: a comprehensive review

The extraction of polyphenols, a class of bioactive compounds widely valued in various fields, has evolved significantly with the emergence of green solvents. Deep eutectic solvents, particularly natural deep eutectic solvents (NaDESs), offer a sustainable and effective solution for polyphenol extraction. This review explores recent advancements in NaDES-based extraction, focusing on its application to agricultural waste, aligning with circular bioeconomy principles. Studies have shown that NaDES significantly enhances polyphenol yield, especially when coupled with advanced techniques like ultrasound-assisted and microwave-assisted extraction. Compared to conventional methods, NaDES-based processes improve extraction efficiency while preserving bioactivity. Notably, polyphenol recovery from vegetables has been observed to be higher than from other sources, highlighting the potential of NaDES for industrial applications. Despite these benefits, challenges such as high solvent viscosity, recovery complexities, and large-scale feasibility remain critical hurdles. Addressing these issues through optimized NaDES formulations, water content adjustments, and process improvements is essential for successful industrial implementation. This review highlights the benefits of NaDES in polyphenol extraction and suggests solutions to improve its industrial feasibility.