A green integrated process for the valorisation of Chinese quince phenolics: Ultrasound-assisted natural deep eutectic solvent extraction and macroporous resin purification followed by UPLC–TQ–MS/MS-based quality control

This study first established a green, integrated process coupling ultrasound-assisted natural deep eutectic solvent (UA-NADES) extraction with macroporous resin purification to obtain Chinese quince total phenolics (CQ-TP). L-proline/glycerol (molar ratio 2:5; Pro-Gly) was identified as the optimal extraction solvent among eleven synthesised NADESs and four common solvents. The optimised UA-NADES extraction process (35% water in Pro-Gly, 40 °C, 300 W, 36 min, liquid-to-solid ratio 30 mL/g) yielded 59.14 ± 0.65 mg/g CQ-TP, markedly higher than the yields from conventional methods. NKA-9 resin showed superior adsorption and desorption performance for CQ-TP, with adsorption behavior consistent with the Langmuir isotherm and a pseudo-second-order kinetic model. Column purification achieved a CQ-TP purity of 72.54 ± 0.81%. Finally, nine main phenolic constituents in the purified CQ-TP extract were quantified by UPLC–TQ–MS/MS to enable batch-to-batch consistency monitoring. This work will significantly contribute to the valorization of Chinese quince phenolics and the development of natural antioxidants.