Impact of salt content and hydrogen peroxide-induced oxidative stress on protein oxidation, conformational/morphological changes, and micro-rheological properties of porcine myofibrillar proteins.

Salting and rehydration of myofibrils can be interfered with free radical diffusion process. This study investigated the effects of salt content (0, 1, 3 and 5%) and H2O2/ascorbate-based hydroxyl radical (OH)-generating system (1, 10, 20 mM H2O2) on the oxidation, conformation, aggregation, and thermal stability of porcine myofibrillar proteins (MPs). Results showed that 5% of salt inhibited carbonylation of MPs with intensive sulfhydryl loss and tryptophan quenching. Fourier transform infrared (FTIR), laser light scattering, and scanning electron microscopy (SEM) suggested that 20 mM H2O2 transformed more α-helix into β-sheet of MPs, favoring larger aggregates being selectively exposed towards solvent during salt-induced fiber swelling. Oxidized MPs brined with ≤1% salt underwent partial unfolding with higher flexibility, while up to 5% of salt greatly hampered their hydration potential and weakened inter-fibrillar hydrogen bond with an improved protein solubility. Micro-rheology revealed that 1% of salt and 10 mM H2O2 rendered a denser structure of heat-set MPs gels.