Rheological properties and structure of myofibrillar protein extracted from Oratosquilla oratoria muscle as affected by ultra-high pressure

Oratosquilla oratoria rich in myofibrillar protein is often shelled, but traditional methods of shelling have certain limitations. In order to better apply the ultra-high pressure (UHP) technology for shelling, the effects of UHP on rheological properties and structure of myofibrillar protein (MP) from O. oratoria treated with a pressure of 300-400 MPa were determined by rheometer and circular dichroism spectrometer. The results showed that in the frequency ramp tests using rheometer, the complex viscosity and G' of MP decreased by 59.08% and 73.70%, respectively, when the pressure reached 400 MPa with holding time of 8 min. As frequency increased, the MP exhibited shear thinning; meanwhile, its storage modulus (G') increased, and solid characteristics became more prominent. In the temperature ramp tests, the MP denatured and its fluidity increased with the increase of temperature. Moreover, the MP from O. oratoria treated with UHP was degraded, and the ionic bond and hydrogen bond were destroyed, while the hydrophobic interaction and disulfide bond increased; the structure of alpha-helix and beta-sheet in the MP converted to beta-turn with the increase of pressure and holding time. These findings can provide references for the application of UHP in food processing.