Viscoelastic behavior of aqueous tertiary systems of whey protein isolate and balangu-wild sage seed gums

Frequency sweep test (0.01-10 Hz) was used to study the effect of 1:1 mixtures of balangu-wild sage seed gums (BSG-WSSG) (0, 0.1, 0.5 and 1% w/w) on the viscoelastic behavior of whey protein isolate (WPI) (6% w/w). The rheological measurements were implemented at three different pHs (4.5, 5.8 and 6.7), constant ionic strength of 50 mM (NaCl) and at 20 °C. The results indicated high frequency dependency of dynamic moduli (G′, G″) with gum concentration, which was more evident at pH4.5 than two other pHs. Modeling of the mechanical spectra using power law equations (G′=a′ωb′, G″=a″ωb″) showed that for all samples, the liquid–like behavior was more dependent on the frequency than the solid–like one. At each three pHs, the complex viscosity decreased with frequency, indicating the shear–thinning behavior of the samples. At very low frequencies, the phase angle (δ) of the solutions was relatively low (δ < 45°), showing the dominant effect of the elastic component. The mixtures with high δ at very high frequencies indicated the dominant effect of the viscous component.

کلیدواژه ها:

Whey protein isolate ، Balangu seed gum ، Wild sage seed gum ، Viscoelasticity