Interaction between fish gelatin and tremella polysaccharides from aqueous solutions to complex coacervates: Structure and rheological properties

In the food industry, there has been a debate about the interactions between fish gelatin and polysaccharide with the interaction mechanism in different solute and solvent systems still unclear. This article tries to explore in- teractions between fish gelatin (FG) and Tremella polysaccharides (AP) by the turbidity titration. Especially, the turbidity was greatly influenced by pH, polymer ratio, total polymer concentration, and ionic strength. Opti- mally, the most complex coacervates could be electrostatically formed at a mass ratio of 1:1 and pH 4.0, which was collected for subsequent characterization. In addition, there was a positive correlation between the turbidity and the total concentration, while the ionic strength was just reverse. Modern instruments including FTIR, XRD, DSC, SEM and rotational rheometer were adopted to characterize the complex coacervates formed at different pH. Results showed that the FG-AP complex coacervates showed porous network structure and had the strongest apparent viscosity with viscoelastic modulus at pH 3.5. These results suggested important implications in how we make a good alternative for fat in food dairy.