Micro-phase separation and rheological behavior of whey protein isolate/gellan gum mixed gels

Abstract

This study was based on the cold gelation process of whey protein isolate (WPI) induced by acid. By regulating the addition concentration of low-acyl gellan gum (LGG), WPI/LGG mixed gel systems with different micro-phase separation behaviors were prepared, and the regulatory mechanism of LGG concentration on the micro-phase separation of the gel was systematically explored. The experiments showed that the change in LGG concentration significantly affected the cold gelation characteristics and dynamic rheological behavior of the mixed gel. Further, this study innovatively introduced a fractional derivative model to quantitatively characterize the linear viscoelastic response of WPI/LGG mixed gels, successfully capturing the dynamic laws of the complex modulus, steady state shear viscosity, and creep response with the change in LGG concentration. The model prediction results were highly consistent with the experimental data (R² > 0.98), demonstrating the potential of the fractional derivative model in modeling and predicting the linear viscoelastic response of WPI/polysaccharide mixed gels. Secondly, by analyzing the constitutive parameters in the model - quasi-properties and fractional order, a phase space map was constructed that could correlate gel firmness with structural characteristics, revealing the quantitative mapping relationship between LGG concentration and the macroscopic properties of the gel. That is, based on the appropriate structural components and combined with the prediction of the mathematical model, the desired firmness texture effect can be achieved, thereby providing a reference for the application of LGG as a gel modifier in the food industry.