Rheological and Microstructural Characteristics of Thermally Produced Flaxseed Gum–Whey Protein Isolate Mixed Solutions and Gels

Abstract

The rheological, thermal gelation, and microstructural properties of flaxseed gum–whey protein isolate (WPI) mixtures were studied using steady shear viscometry, small amplitude oscillatory rheometry, differential scanning calorimetry (DSC), and confocal laser scanning microscopy (CLSM). The concentration of flaxseed gum was varied from 0.1%–0.5% (w/w) while the concentration of WPI was maintained at 20% (w/w). The addition of flaxseed gum increased the viscosity of flaxseed gum–WPI solutions and the strength of the mixed gels. The degree of increase in gel strength was found to depend on the concentration of flaxseed gum. The gel strength of the flaxseed gum–WPI mixed gels increased with the increase of flaxseed gum at low gum concentrations (0.1%–0.3% w/w). The gel strength of these mixed gels decreased (but it was still higher than WPI only gel) at high flaxseed gum concentration (0.5% w/w) due to excessive phase separation caused by thermodynamic incompatibility. This phase separation was clearly visible in micrographs obtained from CLSM.