To process high-quality surimi products, this study investigated the effect of adding polysaccharides with five different degrees of hydrophobicity (contact angles of oligofructose, inulin, potato starch, glutinous rice starch, and wheat fiber were 19.2°, 30.2°, 39.1°, 72.8°, and 101.9°, respectively) to surimi on its gelation properties. The results showed that with the increase in the hydrophobicity of polysaccharides, the strength, hardness, elasticity, chewability and water-holding capacity of surimi gel increased first and then decreased. When adding potato starch with a contact angle of 39.1°, the values of above indicators are the highest, which increased by 26%, 14%, 1.02%, 10%, and 8% compared to the blank group without added polysaccharides, respectively. The brightness (L*) and whiteness of surimi gel decreased with the increase in the hydrophobicity of polysaccharides. In addition, the denaturation temperature and enthalpy value of myosin in surimi first increased and then decreased. Likewise, the degree of transformation of protein secondary structure in surimi gel from α-helix to β-sheet, the intensity of chemical forces (ionic bonds, hydrophobic interactions, and disulfide bonds), and the density of the network structure all increased first and then decreased. Overall, when adding polysaccharides with a contact angle of around 40° most effectively improved the gelation properties of surimi.

Konjac glucomannan (KGM) with a contact angle 60.6° was used as raw material to prepare de-acetylated konjac glucomannan (DKGM) (contact angles of 42.7° and 53.5°) and carboxymethylated konjac glucomannan (CKGM) (contact angles of 68.5° and 72.7°). The effect of the hydrophobicity of modified KGM on the characteristics of silver carp surimi gel was studied. The results showed that the whiteness of the surimi gel added with KGM was 78.20, and the whiteness of the surimi gels added with DKGM and CKCM was 76.77–76.83 and 75.75–75.97, respectively. Compared with KGM, addition of DKGM with contact angles of 42.7° and 53.5° increased the gel strength of surimi by 50% and 73%, respectively; addition of CKGM with contact angles of 68.5° and 72.7° increased the gel strength of surimi by 60% and 43%, respectively. The changes of hardness, elasticity, cohesiveness, chewiness, resilience and water-holding capacity were consistent with the changing trend of gel strength. With the increase in DKGM’s hydrophobicity, the chemical interactions of the surimi gel added DKGM increased, the relative content of α-helix decreased, the relative content of β-sheet increased, the thermal stability of myosin increased, and the network structure became denser. The opposite results were observed with the addition of CKGM. The above results indicate that the modification method and hydrophobicity of KGM jointly affect the gel properties of surimi.