The effect of pH and salt on the stability and physicochemicalproperties of oil-in-water emulsions prepared with gum tragacanth

Khadije Abdolmaleki, Mohammad Amin Mohammadifar, Reza Mohammadi, Ghasem Fadavi, Neda Mollakhalili Meybodi

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The effect of pH (2.5, 4.0 and 5.4) and salt concentration (0.0, 0.5 and 1.0 wt%) on the physical stability of oil-in-water emulsions stabilized with gum tragacanth were investigated during 150 days of storage. Mean droplet diameter, zeta-potential, interfacial tension and steady-shear and dynamic rheological properties were determined to achieve more information about the likely stability mechanisms. The results showed that increasing salt concentration did not have a significant effect on emulsion stability. Emulsions were highly unstable at pH 2.5, with their emulsion-stability index declining almost three times more than that of other emulsions during the storage time. Based on the size distribution data, a direct correlation was not observed between droplet size distribution and emulsion stability. Rheological analysis revealed that pH 2.5 had the lowest apparent viscosity, storage modulus, energy of cohesion (EC) and a-value, and the highest tan δ and b-value.
Original languageEnglish
JournalCarbohydrate Polymers
Pages (from-to)342–348
Publication statusPublished - 2016
Externally publishedYes


  • Gum tragacanth
  • Emulsion stability
  • Rheological properties
  • Particle size
  • Interfacial tension
  • Zeta potential

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