Effect of curdlan on improving the property deterioration of fish gelatin gels induced by high temperature: An exploration of gel properties, structure and interaction mechanism

High temperatures (>90 degrees C), which are commonly employed in the traditional processing of fish gelatin-based meat products, would cause the degradation of fish gelatin (FG) and finally result in a quality decline of the gels. Curdlan (CD) was used to improve the quality and thermostability of fish gelatin gels. Results showed that CD and FG could form a composite gel with compact 3D network structure. The addition of 1.5 wt% CD significantly increased the hardness (58.42 %), gumminess (30.58 %), chewiness (34.02 %), and water holding capacity (26.65 %) of 3.0 wt% FG gels. In addition, the composite gel exhibited a good thermostability even it was exposed at 100 C-degrees for 1 h. Moreover, CD modified the amino acid microenvironment of FG molecules by increasing the surface hydrophobicity and attenuating endogenous fluorescence, which promoted the aggregation of FG molecules and led to an increase in their particle size. The microstructure, Fourier transform infrared spectroscopy, X-Ray diffraction, and differential scanning calorimetry analysis results revealed that CD could significantly increase the formation of hydrogen bonds within gels and change the secondary structure of FG protein at high temperatures. This could make the helicoidal structure more stable and ordered, establish a more uniform and dense 3D network structure, and improve the thermostability. This study might provide reference for improving the quality and stability of fish gelatin-based products under high-temperature processing.