Synergistic strongly coupled super-deamidation of wheat gluten by glucose-organic acid natural deep eutectic solvent and the efficaciousness of structure and functionality

The synergistic coupled improvement of functional properties by natural deep eutectic solvent (NADES) super-deamidated wheat gluten (WG) was investigated. Screening by eight NADESs, glucose-citric acid NADES (G-C, molar ratio at 2:1) super-deamidated WG (SDWG-N) exhibited the exceeding emulsification properties (22.37 m2/g) and foaming stability (85.61%), which were significantly higher than those of citric acid deamidated WG (CDWG). Degree of deamidation and protein recovery of SDWG-N (26 mg/mL) reached 95.47% and 96.77% respectively at 121 °C for 14 min at the condition that G-C was diluted to 18% (v/v). Supra-molecular structural properties of G-C NADES reflected that the charge inhomogeneity of G-C promoted the affinity of water to the amide groups via ionizing more H+ and formed hydrogen bonds with amino acid residues, thus achieving the strong coupling super-deamidation of WG. SDWG-N showed higher stability as function of pH 2–12 than CDWG. Fluorescence and FTIR spectra explored more unfolded and flexible with greater exposed hydrophobic groups and lower degree of aggregation of SDWG-N, which exhibited the synergistic coupled effect of super-deamidation by G-C on WG. It suggested that SDWG-N would be used as a strong stabilizer at water/oil and gas/water interface with further potential to cooperate with other macromolecules for food use.