Effects of salt ions on rheological properties of SPI-GG hybrid system

The rheological characteristic of soy protein isolate (SPI), is one of the most important properties in its application in food industry. The effects of different concentrations of guar gum (GG, polysaccharide) and sodium chloride (salt ion) on the rheological properties of SPI were studied in this research. Steady-state shear, strain sweep and frequency sweep tests (static and dynamic rheological tests) were performed, and the following phenomenon and conclusions were drawn: (1) The viscosity of the hybrid system increases with the GG addition. This trend could also be seen with the appropriate adding of salt ion; (2) As the applied frequency increases, the storage modulus G′ and the loss modulus G″ of the hybrid system increase at a similar rate. And the frequency sweep parameters of the hybrid system rise significantly with the increase of both GG and ionic concentration; The frequency dependence of the system varies significantly with the addition of salt ion; (3) With the concentration of the salt ion increase, the storage module G′ of the hybrid system decrease indicating that salt ion destroyed the network structure of hybrid dispersion to a certain extent.