Effects of lipoxygenase/linoleic acid on the structural characteristics and aggregation behavior of pork myofibrillar protein under low salt concentration

The present study sought to explore the effects of lipoxygenase/linoleic acid (LOX/LA) oxidation system treatment on protein oxidation, structural characteristics, aggregation behavior, rheological and morphological properties of pork myofibrillar protein (MP) at low salt condition (0.1 M NaCl). Incubation of MP with LOX/LA converted protein sulfhydryl groups to disulfide bonds and promoted carbonylation in a concentration-dependent manner. MP structure unfolded from α-helix to β-sheets with increase in LOX concentration (0–2500 U/mL), and buried hydrophobic residues were exposed as shown by the results from circular dichroism and fluorescence spectroscopy analysis. Particle size distribution and SDS-PAGE analysis showed that LOX/LA treatment promoted MP aggregation to form oligomers. These results were further validated using atomic force microscopy (AFM). Analysis of rheological properties indicated moderate LOX/LA (<1000 U/mL) system treatment significantly decreased storage and loss modulus of MP gel. These findings indicate that LOX can be used to improve the gelling properties of MP at low salt concentration.