Effects of 2,2′-Azobis(2-methylpropionamidine) Dihydrochloride Stress on the Gel Properties of Duck Myofibrillar Protein Isolate

The aim of this study was to investigate the biochemical properties and gel-forming capacity of duck myofibrillar proteins under the effects of 2,2′-azobis(2-methylpropionamidine) dihydrochloride (AAPH)-mediated oxidation. Duck myofibrillar proteins were extracted and treated with different concentrations of AAPH solutions (0, 1, 3, 5, 10 mmol/L) and then analysed for carbonyl content, dynamic rheology, protein profiles and gel-forming properties (colour, water holding capacity, gel strength and microstructure). The results showed that with increasing AAPH concentration, the carbonyl content of the proteins exhibited an increasing trend (p < 0.05); SDS-PAGE pattern changes indicated that moderate oxidation (3 mmol/L AAPH) induced myosin aggregation via covalent bonds including disulfide, enhanced protein–protein interactions, and thus affected the gel strength of the DMPs’ heat-induced gels. However, high oxidation (5 and 10 mmol/L AAPH) led to the partial degradation of the myosin heavy chain (MHC) isoforms, as evidenced by lower storage modulus and irregular microstructures, which significantly reduced gelation ability. These results suggest that the internal relationship between alkylperoxyl radical-induced oxidation should be taken into account in the processing of duck meat, as mild protein oxidation is conducive to improving gel quality.