Binding of aroma compounds with myofibrillar proteins modified by a hydroxyl-radical-induced oxidative system

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.