Structural properties and emulsification of myofibrillar proteins from hairtail (Trichiurus haumela) at different salt ions

The structural properties and emulsification of myofibrillar proteins (MPs) are susceptibly affected by salt ions. The effect of different salt ions on the structural properties and emulsification of MPs from hairtail (Trichiurus haumela) remains unclear. Hairtail MPs were analyzed under different ion treatments of Na+, K+, Ca2+ and Mg2+. MPs at K+ and Na+ treatment showed a similar trend on salt effect due to the unfolding of proteins under salt ions. However, the excessive electrostatic effect of divalent ions could enhance protein aggregation, especially at Ca2+ and Mg2+. The β-sheet of MPs at different salt ions interconverted with α-helix and random coil at ionic strengths from 0.1 mol/L to 1.0 mol/L. The surface hydrophobicity and active sulfhydryl content of MPs increased with the improvement of ionic strengths at 0–0.8 mol/L. Under Ca2+ and Mg2+ treatments, the turbidity of MPs was low compared to that under the treatment of Na+ and K+. Additionally, the emulsification of hairtail MPs treated with different ions was improved at an ionic strength of 0.6 mol/L. This study can contribute to using salts in constructing fish protein-based emulsions for manufacturing emulsified surimi products and promoting the development and utilization of hairtail proteins.