Effect of Sodium Chloride Content on Gel Properties and Structure of Tilapia Fish Skin Gelatin

The effect of sodium chloride concentration (0, 0.5%, 1.0%, 1.5%, 2.0%, 3.0%, w/v) on the true stress, Young's modulus, enthalpy and structure of different tilapia fish skin gelatin gel concentrations (2%, 4%, 6.67%, w/v) was measured by uniaxial compression, differential scanning calorimetry (DSC) and Fourier transform infrared spectrometry (FT-IR).The results showed that the true stress and Young's modulus incresed which indicated gel strength and firmness increased with the increaseing of gelatin concentrations. After the addition of sodium chloride, the gel strength and firmness decreased, while sodium chloride content was reached to 3%, the gelatin gel strength and firmness achieved a least value.DSC analysis showed that heat flow decresed which indicated the cross-linking degree of the fish gelatin gel network systerm weakened. FT-IR analysis showed that amide I band moved to low wave numbers with the increaseing of sodium chloride concentrations, the formation of hydrogen bonds in gelatin gels was inhibited, the gel strength was decreased.The experimental results showed that the presence of sodium chloride destroyed the spatial structure of the gelatin samples and reduced the gelation properties of the fish gelatin gel.