Improving the gelation and digestive properties of myofibrillar protein in Litopenaeus vannamei by ultra-high pressure

The objective of this study was to investigate the effects of ultra-high pressure (UHP) on the physicochemical properties, gelling properties, and in vitro digestion characteristics of myofibrillar protein (MP) in Litopenaeus vannamei. The pressures were set at 0, 150, 300, 450, and 600 MPa, respectively. The α-helix structure gradually unfolded and transformed into β-sheet structure as the pressure increased from 0 to 600 MPa. Compared with the control group, the content of α-helix structure of the 600 MPa-treated MP samples decreased by 51.31%, and the content of β-sheet structure increased by a 1.34-fold. In addition, the UHP treatment enhanced the rheological properties of MP. The elastic modulus (G′) and viscous modulus (G″) of the 600 MPa-treated MP samples increased by 4.77-fold and 3.78-fold, respectively, compared with the control group (at frequencies up to 10 Hz). The gel properties of the MP also increased significantly after UHP treatment, e.g., the WHC of MP gel increased by 45.49% and the gel strength increased by a 5.99-fold when the pressure reached 600 Mpa, compared with the control group. The results of in vitro simulated digestion showed that UHP treatment led to the formation of more easily digestible MP gels. Compared with the control group, the 600 MPa-treated MP gel samples showed a 1.89-fold increase in digestibility and a 66.86% decrease in digestible particle size.