Deep eutectic solvent-based ultrasonic-assisted extraction of polyphenols from Macadamia integrifolia green peel: COSMO-RS screening, process optimization, and its application in chitosan/polyvinyl alcohol films

Deep eutectic solvents (DESs)-based ultrasonic-assisted extraction (UAE), as an efficient extraction method, was used to extract polyphenols from macadamia green peel (MGP). Based on a prediction results of a conductor-like screening model for realistic solvents, 20 DESs were preliminarily selected from 696 DESs for experimental validation, with choline chloride-1,2-butanediol (1,1, molar ratio) exhibiting the highest extraction efficiency. UAE conditions were optimized through response surface methodology experiments, and a total phenolic yield of 91.09 ± 1.15 mg GAE/g DW was obtained. Furthermore, the DES-based MGP phenolic extract was incorporated into chitosan/polyvinyl alcohol films as a plasticizer, resulting in significant changes in physical properties and an increase in antioxidant activity and ultraviolet-blocking properties. Molecular simulations revealed that hydrogen bonding and van der Waals interactions forces the DES-polyphenol interaction. These findings provide a comprehensive strategy for the efficient extraction and functional utilization of MGP polyphenols.