Effect of molecular weight of dextran on the phase behavior and microstructure of preheated soy protein/dextran mixtures

The effects of molecular weight of dextran on the phase behavior and microstructure of preheated soy protein (heat-induced soy protein aggregate)/dextran mixtures have not been reported before. Hereby mixed systems of heat-induced aggregates with different size and dextran with different molecular weight have been investigated at room temperature (25 °C) and pH 7.0. Phase diagrams were established by centrifugation, chemical assays and visual observation. The mixture of dextran with larger molecular weight and larger aggregate phase separated at lower biopolymer concentration. The microstructures of the phase separated mixtures were described using confocal laser scanning microscopy (CLSM), which revealed the association of protein aggregates. The image analysis of the CLSM images showed that the histograms of the gray values were different significantly. Observations of small deformation rheology (G′, G′′) of the mixed system at concentrations corresponding to those of CLSM measurements provided additional information of the microstructures.