Phase behavior and rheological properties of basil seed gum/whey protein isolate mixed dispersions and gels

Many food formulations comprise proteins and polysaccharides simultaneously, contributing in the functional properties in food systems. In this study, the effects of basil seed gum (BSG) addition to whey protein isolate (WPI) dispersions were investigated through phase behavior, steady shear flow, and small amplitude oscillatory shear tests (SAOS). The phase behavior of WPI-BSG mixed solutions was dependent on the initial concentration of biopolymers, while the effect of BSG was predominant. Herschel-Bulkley model characterized the flow behavior of ternary mixtures, very well. Furthermore, apparent viscosity, the extent of thixotropy and viscoelastic behavior enhanced with increase in BSG concentration, significantly (p < .05). Temperature sweep measurements showed a reduction in WPI gelling temperature by increase in BSG concentration. SEM results depending on BSG concentration revealed the protein continuous, bicontinuous, and polysaccharide continuous networks. Phase separation may be attributed to depletion flocculation and thermodynamic incompatibility of WPI and BSG molecules. The results confirmed the occurrence of phase separation and weak-gel formation through mixtures, but the rate of gelation was more than the phase separation. In consequence, these results may open up new horizons in developing novel food products and delivery systems as well as utilizing as emulsifying, thickening and gelling agents in food and pharmaceutical industry.