title: The effect of pH and salt on the stability and physicochemical properties of oil-in-water emulsions prepared with gum tragacanth.
abstract: The effect of pH (2.5, 4.0 and 5.4) and salt concentration (0.0, 0.5 and 1.0wt%) 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 tanδ and b-value.
authors.affiliation: Department of Food Science and Technology, National Nutrition and Food Technology, Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti, University of Medical Sciences, Tehran, Iran. Electronic address: khadije.abdolmaleki@gmail.com.
authors.forename: Khadije
authors.initials: K
authors.lastname: Abdolmaleki
authors.affiliation: Department of Food Science and Technology, National Nutrition and Food Technology, Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti, University of Medical Sciences, Tehran, Iran. Electronic address: mohamdif@ut.ac.ir.
authors.forename: Mohammad Amin
authors.initials: MA
authors.lastname: Mohammadifar
authors.affiliation: Department of Food Science and Technology, Faculty of Public Health, Kermanshah University of Medical Sciences, Kermanshah, Iran. Electronic address: R.mohammadi@sbmu.ac.ir.
authors.forename: Reza
authors.initials: R
authors.lastname: Mohammadi
authors.affiliation: Food Industry Research Group, Faculty of Food Industry and Agriculture, Standard Research Institute, Karaj, Iran. Electronic address: fadavi@standard.ac.ir.
authors.forename: Ghasem
authors.initials: G
authors.lastname: Fadavi
authors.affiliation: Research Center for Molecular Identification of Food Hazards, Shahid Sadoughi University of Medical Sciences, Yazd, Iran. Electronic address: neda_mabodi@yahoo.com.
authors.forename: Neda Mollakhalili
authors.initials: NM
authors.lastname: Meybodi
mesh_terms: D055598:Chemical Phenomena; D004655:Emulsions; D006863:Hydrogen-Ion Concentration; D009821:Oils / Q000737:chemistry*; D010316:Particle Size; D012212:Rheology; D012492:Salts / Q000737:chemistry*; D014144:Tragacanth / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D004655:Emulsions; D009821:Oils; D012492:Salts; D014867:Water; D014144:Tragacanth
keywords: Emulsion stability; Gum tragacanth; Interfacial tension; Particle size; Rheological properties; Zeta potential