Influence of soybean polysaccharide on the physical stability and rheological properties of whey protein isolate emulsion

To increase the elasticity, viscosity of the food system and form high rheological properties food system, the effect of different concentrations of soybean polysaccharide ( SSPS) on whey protein isolates ( WPI) coated emulsion 's stability and rheological properties was investigated. The particle size, Zeta-potential, stability index, rheological properties and microstructure of the emulsion were analyzed by electrostatic mixing of different concentrations of SSPS and 2% WPI emulsion ( oil phase 20%) .In order to deeply explore the effect of WPI emulsion's rheological properties, combined shear rheology and micro-rheological technology were applied.The results showed that with the increase of SSPS concentration, the particle size of WPI emulsion reached the peak value ( 3350 ± 0.35) nm with 0.25% SSPS, and then decreased with the increase of SSPS concentration.The absolute value of Zeta-potential decreased, indicating that electrostatic interaction between SSPS and WPI emulsion and SSPS electrostatic adsorption improved the stability of WPI emulsion.Shear rheology results showed that when the concentration of SSPS was 0.5%, the viscosity reached the maximum value and the viscosity value was more than 10 times that of the WPI emulsion at the shear rate of 95.8 s-1. Micro-rheological results showed that the MSD curve of 0.5% SSPS-WPIemulsion appeared in the platform area, indicating that the elasticity index ( EI) and the macroscopic viscosity index ( MVI) significantly increased and reached the maximum. Microstructure results showed that 0.5% SSPS-WPI emulsion formed a homogeneous emulsion aggregate.This study could help to understand the interaction between SSPS and protein emulsions and provide theoretical guidance for food ( mayonnaise, sauces, chocolate and butter, etc.) production with low fat and high rheological properties.