Natural deep eutectic solvent enhanced pulse-ultrasonication assisted extraction as a multi-stability protective and efficient green strategy to extract anthocyanin from blueberry pomace

A deep understanding upon the relation between anthocyanin extraction performance and physicochemical properties of natural deep eutectic solvents (NADESs) was obtained, and a high-efficiency NADES (Choline chloride-Oxalic acid (ChOa)) was selected and coupled with pulse-ultrasonication for anthocyanin extraction from blueberry pomace. Response surface methodology was adopted to analyzed the significant factors’ influence, interactive effects on extraction yield and optimize the extraction conditions. The theoretical optimal conditions with highest yield of total anthocyanins content (TAC) were 3.2 min of ultrasonic time, 325 W of ultrasonic power, 349.15 K of temperature, 60 mL/g of solvent to solid ratio, under which the experimental TAC value (24.27 ± 0.05 mg C3GE/g DW) was highly correlated with theoretical result (24.28 mg C3GE/g DW). Multi-stability protective effect of ChOa on anthocyanin over acidified ethanol was revealed by stability assays in high temperature, varying pH and light exposure conditions. FT-IR and DSC analysis further characterized the influence of ChOa over acidic ethanol on typical anthocyanins functional groups and thermal behavior of anthocyanin extracts. UPLC-Triple-TOF/MS analysis identified 10 anthocyanins that mainly consisted of delphinidin, petunidin, and malvidin compounds. Overall, this study provided a green, high-efficiency and multi-stability protective strategy for the recovery of anthocyanins from plant source by-products. • ChOa based P-UAE showed excellent efficiency in green extraction of anthocyanin. • ChOa showed multi-stability protective effect on extracted anthocyanin. • Relation between physicochemical indexes of NADESs and extraction was revealed. • ChOa influences the structure, thermal behavior and composition of anthocyanin. • Conditions of ChOa based P-UAE were optimized using RSM.