Temperature dependence of stability, steady and dynamic rheological properties of oil-in-water emulsions stabilized by gum tragacanth
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In this paper, the effects of four different temperatures (5, 25, 37 and 50 °C) on the physical stability and the dynamic and steady-state shear rheological properties of sunflower oil-in-water emulsions prepared with gum tragacanth were investigated. Emulsions showed excellent stability against various instability mechanisms after 150 days storage at 5 and 25 °C. The experimental data had the best fit with power law model (R2 > 0.99). The effect of temperature on power law parameters was determined. The increase of temperature from 5 to 50 °C resulted in 4 times decrease in the flow consistency index, whereas the flow behavior index slightly enhanced with temperature (0.49–0.58). For all samples loss modulus (G″) was higher than the storage modulus (G′) in the low frequency range and G′ increased faster than G″ with frequency enhancement. A modified Cox–Merz rule was valid to emulsion samples using shift factors.
KeywordsOil-in-water emulsions Physical stability Cox–Merz rule Storage modulus Loss modulus
This research is linked to the project with number of 1396/62421 from Student Research Committee, Shahid Beheshti University of Medical Sciences, Tehran, Iran. We thank the “Student Research Committee” for their financial support of this study.
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