Green extraction of polyphenols from food and agricultural waste using NADES and non-thermal technologies: Mechanisms, optimization, and circular bioeconomy applications

The growing demand for natural polyphenols in functional foods, nutraceuticals, cosmetics, and sustainable materials has intensified global interest to extract them from food and agro-industrial waste streams. Conventional extraction of polyphenol compounds using organic solvents has been found unsustainable, ineffective or uneconomical due to the loss of bioactivity, high consumption of energy, use of toxic solvents, and poor selectivity. To overcome these limitations and to address sustainability aspect, the emerging area of green chemistry has undergone tremendous developments, with a wide range of strategies involving natural deep eutectic solvents (NADES) and non-thermal technologies. As a result, a significant number of NADES-based platforms with high yields of polyphenol compounds have been developed. Research on hybrid platforms composed of NADES and non-thermal technologies such as ultrasound, pulsed electric field, high pressure, and cold plasma (CP) has also made tremendous advances with the increasing volume of scientific activity and publications This review covers the recent developments and major breakthroughs in the synergistic use of NADES and non-thermal technologies, focusing on their fundamental molecular principles and efficiency to recover polyphenols from food and agro-industrial residues. We also highlight existing challenges and key hurdles in this field and provide insights into their rapidly growing potential for circular applications. Finally, a possible outlook is projected for the design of edible or highly effective NADES solvent systems using artificial intelligence and machine learning algorithms. The new NADES-enabled non-thermal platforms have opened exciting opportunities for the recovery of polyphenols with high efficiency and support the transition to waste valorization and circular bioeconomy.