Breakdown properties and sensory perception of whey proteins/polysaccharide mixed gels as a function of microstructure.

Whey protein isolate (WPI)/polysaccharide mixed gels used in the current study formed homogeneous and phase separated microstructures as visualized by confocal laser scanning microscopy (CLSM). The latter can be further classified into protein continuous, bicontinuous and coarse stranded microstructures. Quantitative descriptive analysis (QDA) was used to evaluate sensory properties of the gels. The gels were subjected to large deformations by uniaxial compression. The microstructure affects the gels breakdown properties as well as serum release which occurred during compression of the gels. Protein continuous and bicontinuous gels fractured through the protein network. They fractured along only a few crack planes, whereas in coarse stranded gels cracks were formed at many places which was accompanied by coarsening of the protein network. Serum release was strongly correlated with gels porosity. Highly porous gels, i.e., bicontinuous and coarse stranded ones, released higher amount of serum than the other gels. In addition, serum release affected large deformation and fracture properties of the gels. QDA panel tests showed that breakdown mechanisms and serum release were the major factors in sensory perception of the gels. Gels fracturing only along a few planes were perceived as firm and crumbly whereas gels showing multiple fracture events were perceived as spreadable. Gels releasing high amount of serum were perceived as watery. The study confirmed the essential role of microstructure in sensory perception of mixed gels