Abstract: This study investigated the effect of ultra-high pressure (UHP) treatment on gel characteristics and myofibrillar protein structure in hairtail surimi. Changes in the gel strength, whiteness, texture properties and microstructure and the content and molecular conformation myofibrillar protein were measured after UHP treatment at different pressures for different times or heat treatment. The results showed that UHP could induce the formation of a network structure in surimi gel, and improve texture parameters, gel strength and whiteness compared to the control group. Scanning electron microscopy showed that the gel network structure of surimi treated with 350 MPa for 8 min (350-8 group) was close to that of the heat-induced group. UHP treatment reduced the content of myofibrillar protein in the surimi gel, and led to the gradual disappearance of the two negative grooves in the circular dichroism (CD) spectrum of myofibrillar protein. Meanwhile, the relative content of α-helix structure decreased, but the random coil and β-sheet contents increased to varying degrees. The random coil content of myofibrillar protein in the 350-8 group was close to that in the heat-induced group. Conclusion: Appropriate UHP treatment (at 350 MPa for 8 min) significantly affected the gel characteristics and the secondary structure of myofibrillar protein from surimi, promoted the formation of gel network and improved the quality of surimi gel.

Key words: ultra-high pressure, hairtail surimi, gel properties, myofibrillar protein, circular dichroism