Effect of sodium chloride on the visual appearance, gelling properties and structural characteristics of gelatin-low acyl gellan gum

Sodium chloride (NaCl) was used to enhance the transparency in the composite system of gelatin and low acyl gellan gum (GL). At the same time, the gelling properties and structural characteristics of the composite system were evaluated in detail. The appearance of the composite system showed that NaCl significantly improved the transmittance of the composite solution and the colour of the gel. When the concentration of NaCl was 40 mmol/L, the transmittance of the solution at 450 nm increased from 78.5% to 81.8%, and the brightness of the gel also increased from 27.69 ± 0.21 to 30.85 ± 0.41 ( p<0.05 ). With the increase of NaCl concentration, the gel strength of the composite system was significantly higher than that of gelatin alone, and the melting point gradually increased, reaching the maximum of 50.31 °C at the concentration of 50 mmol/L. In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that NaCl promoted the formation of smaller spherical aggregates in the composite system, resulting in more ordered microstructures and nanostructures. These results provide an experimental basis for the further development of composite gel as a new material in the food industry. • NaCl was added to BG-GL to improve the quality of composite gel. • NaCl induced smaller, more uniform spherical aggregates in the composite gel. • The composite gel with NaCl exhibits high transparency. • The schematic depicted a potential mechanism for NaCl action on the BG-GL complex.