Effects of Gel Properties and Water Migration during Ultra-High Pressure Coupled Heat Treatment on Bighead Carp Surimi

In order to elucidate the mechanism of the changes in gel properties of bighead carp surimi during ultra-high pressure coupled heat treatment, this paper investigated the changes in gel properties, protein structure and water migration of bighead carp surimi during ultra-high pressure coupled heat treatments (300 MPa/5 min, 40 ℃/30 min, 90 ℃/20 min), and carried out clustered heat maps and Pearson correlation analyses. The results showed that ultra-high pressure coupled heat treatment significantly improved the gel properties of bighead carp surimi (P<0.05). The gel strength, texture and whiteness of bighead carp surimi gel showed an increasing trend with ultra-high pressure, ultra-high pressure combined with one-stage heat treatment, and ultra-high pressure combined with two-stage heat treatment. The gel strength and whiteness of the ultra-high pressure coupled heat treatment (300PSH) surimi gels increased by 477.75% and 43.38%, respectively, compared to the atmospheric pressure treated samples (0.1P). The proportion of β-folded structure in the proteins of bighead carp surimi gels increased significantly (P<0.05) during the different treatments, and myosin heavy chain cross-linked aggregation. Meanwhile, the content of active sulfhydryl groups and surface hydrophobicity of surimi gel were significantly reduced (P<0.05), and the proteins formed a denser and more ordered network structure through disulfide bonds and hydrophobic interaction, leading to the migration of immobile water to bound water, which ultimately resulted in significant improvements in the gel strength, texture properties, whiteness and water holding capacity of surimi gel. This study can provide theoretical basis for application of ultra-high pressure coupled heat treatment technology and development of bighead surimi products.