The objective of this study was to investigate the influence of oxidation-induced structural modifications of myofibrillar protein on its binding ability with aroma compounds such as 2-methyl-butanal, methional, 2-pentanone, 2-heptanone, and nonanal. A method using solid-phase microextraction (SPME) combined with gas chromatography/mass spectrometry (GC/MS) was used to determine the corresponding binding ability. The binding with aroma compounds was found to be strongly affected by the oxidation levels of proteins, probably due to the varying modifications in protein structure and surface. Incubation with oxidants around or below 1 mM mainly caused the refolding of protein structure and accelerated the protein aggregation, which reduced the affinity of the aroma compounds, thus decreasing the binding ability. Nevertheless, treatment with oxidants over 2.5 mM would cause protein reaggregation and partial degradation, and thus, the subsequent modification of protein surface properties. The aggregated protein with wrinkled surfaces favored the hydrophobic interactions with aroma compounds, forming the protein-aroma compound complex, thus enhancing the resultant binding ability as evidenced by fluorescence quenching and SPME-GC/MS analysis.

•Citric acid deamidation significantly increased gluten solubility at neutral pH.•Secondary structures of DWG were changed during citric acid deamidation.•Digestibility of DWG decreased by pepsin while increased by pancreatin digestion.•DWG digests showed higher essential amino acids content while lower ORAC values.The effects of citric acid deamidation on the physiochemical properties of wheat gluten were investigated. In vitro digestion was carried out to determine changes of molecular weight distribution, amino acids composition and antioxidant efficacy of wheat gluten hydrolysates. Results indicated that citric acid deamidation significantly increased gluten solubility and surface hydrophobicity, at a neutral pH. Deamidation induced molecular weight distribution change of gluten with little proteolysis. Results from FTIR indicated that the α-helix and β-turn of deamidated gluten increased accompanied by a decrease of the β-sheet structure. After deamidation, in vitro pepsin digestibility of wheat gluten decreased, while in vitro pancreatin digestibility increased. The oxygen radical absorbance capacity (ORAC) activity of the in vitro digests decreased with increase of deamidation time. The high Lys and total essential AAs amounts in the final digests suggested that the nutritional values of wheat gluten after deamidation might be enhanced.