Effect of the Hydrophobicity of Modified Konjac Glucomannan on the Characteristics of Surimi Gel

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.