Effect of hydroxyl radical oxidation system on structure of egg white protein

The objective of this study was to determine structural changes, including carbonyls, sulfhydryls, free amino, particle size distribution, secondary structure in egg white protein exposed to FeCl₃/Asc/H₂O₂ hydroxyl radical-generating systems.Protein carbonyl content in EWP increased ( p < 0.05) with increasing concentrations of H₂O₂, free SH, total SH groups and free amino decreased ( p < 0.05) in a similar fashion.EWP average particle size increased.When the H₂O₂ concentration was increased to 20 mmol/L, there was 2.01-fold increase in carbonyl group, 29.1% decrease in free amino acid, compared with control group.The average particle size reached 666 nm.The results showed that there were increases in α-helix and β-fold of relative content, decrease in β-turn of relative content with the increase of oxidizing agent ( H₂O₂< 5 mmol/L) .Higher level oxidation ( H₂O₂> 5 mmol/L) would induce fragmentation through direct breakage of peptide bonds, resulted in changes in the secondary structures.These oxidation-induced changed demonstrate high susceptibility of EWP to oxidative stress.