Enhanced deep eutectic solvent extraction of phenolic compounds from hawthorn seeds with ultrasonic and resin in-situ adsorption assistance: Process optimization, component analysis, and extraction mechanism

s Extraction of bioactive substances from food processing waste is currently an important research topic. Ultrasonic and hyper-cross-linked resin in-situ adsorption method were proposed to synergistically assist in the extraction of phenolic antioxidants from hawthorn seeds using deep eutectic solvents (DESs). DES composed of choline chloride and oxalic acid outperforms other DESs in terms of extraction efficiency. The adsorption of non-polar resin XDA-1 increases the yield of polyphenols and flavonoids by 45.16 % and 3.61 times, respectively. The extraction kinetic curves conform to pseudo-second-order rate model. The extraction yield and rate using DES is markedly superior to that using conventional solvents. The components analyzed using UPLC-MS indicate that the phenolic compounds in extract are mainly ellagic acid, vanillin, hesperetin-7-O-β-D-glucopyranoside, and hesperidin, etc. The primary forces facilitating extraction are hydrogen bonding and van der Waals interactions found by the conductor-like screening model for real solvents calculation.