Effect of ionic strength on the structural properties and emulsion characteristics of myofibrillar proteins from hairtail (Trichiurus haumela).

Myofibrillar proteins (MPs) are susceptibly affected by ionic strength. The effect of ionic strength on the structure and emulsifying properties of MPs from hairtail (Trichiurus haumela) is still unclear. Therefore, the effect of ionic strength on the structural properties and emulsification of myofibrillar proteins from hairtail was analyzed. The increase in ionic strength led to the increase in endogenous fluorescence intensity of MPs. The α-helix content in MPs first increased and then decreased from ionic strength of 0 to 1.0 mol/L and β-sheet content exhibited the oppositive trend, indicating that α-helix in MP transformed into β-sheet. The surface hydrophobic groups of MPs increased; however, the contact angle decreased with the increase in ionic strength of 0-0.8 mol/L and a slight rebound at 1.0 mol/L. Sulfhydryl content and electrophoretic analysis further exhibited the change of MP structure at ionic strengths of 0-1.0 mol/L. Besides, the droplet size of MP emulsions was small and evenly distributed at 0.6 mol/L. Additionally, the creaming index of MP emulsions had better stability prepared at 0.6 mol/L than the other ionic strength conditions. The apparent viscosity of MP emulsions increased with the increase in ionic strength of 0-0.8 mol/L and decreased slightly at 1.0 mol/L. The rheological behavior of MP emulsions exhibited gel-like behavior without the effect of temperatures at 20-80 °C. These results can broaden the potential application of MPs from hairtail on the emulsion-type seafood products and delivery system in the food industry.