Complexation of sodium caseinate with gum tragacanth: Effect of various species and rheology of coacervates

Sara Ghorbani Gorji, Elham Ghorbani Gorji, Mohammad Amin Mohammadifar, Azizollaah Zargaraan

Research output: Contribution to journalJournal articleResearchpeer-review


We investigated complex coacervation of sodium caseinate/. Astragalus rahensis (A.r) as a function of pH with light scattering, spectrophotometry, and viscosity measurements. Interestingly, sodium caseinate/A.r displayed five structural transitions; pH 7.00 to pH ~5.40: no interaction occurred, pH ~5.40 to pH ~4.80: initiation of the formation of primary soluble complexes, pH ~4.80 to ~4.30: formation of interpolymer complexes, pH ~4.30 to ~4.02: optimum coacervation and pH ~4.02 to ~2.50: suppression of coacervation. In addition, rheological properties of sodium caseinate/A.r coacervates were studied at various pH values. A much higher storage modulus (G') than loss modulus (G″) for all sodium caseinate/A.r coacervates suggests the formation of highly interconnected gel-like network structures with mainly elastic behaviour. Moreover, sodium caseinate/A.r coacervates at all pH values exhibited a shear thinning behaviour across the entire shear rate range investigated. Effects of different species of gum tragacanth on the interactions with sodium caseinate have been scarcely studied. Our study showed that systems containing various species (A.r, soluble fraction of A.r and Astragalus gossypinus (A.g)) had different critical pH values and particle sizes during complex coacervation, which could be due to different ratio of soluble to insoluble fractions and uronic acid content of various species. © 2014 Elsevier B.V.
Original languageEnglish
JournalInternational Journal of Biological Macromolecules
Pages (from-to)503-511
Publication statusPublished - 2014
Externally publishedYes


  • Astragalus Plant
  • Caseins
  • Gels
  • Gum Arabic
  • Hydrogen-Ion Concentration
  • Particle Size
  • Phase Transition
  • Rheology
  • Uronic Acids
  • Viscosity
  • Gum tragacanth
  • Particle size
  • Protein–polysaccharide coacervate
  • Rheological property
  • Sodium caseinate
  • Biochemistry
  • Molecular Biology
  • Structural Biology
  • Medicine (all)
  • Protein-polysaccharide coacervate
  • casein
  • caseinate
  • gum tragacanth
  • unclassified drug
  • gel
  • gum arabic
  • uronic acid
  • article
  • coacervation
  • complex formation
  • elasticity
  • flow kinetics
  • light scattering
  • loss modulus
  • nonhuman
  • particle size
  • pH
  • shear rate
  • spectrophotometry
  • storage modulus
  • structure analysis
  • viscosity
  • Astragalus plant
  • chemistry
  • phase transition
  • elastic behavior
  • optimum coacervation
  • pH factor
  • Dicotyledones Angiospermae Spermatophyta Plantae (Angiosperms, Dicots, Plants, Spermatophytes, Vascular Plants) - Leguminosae [26260] Astragalus gossypinus species Astragalus rahensis species
  • gum tragacanth 9000-65-1
  • sodium caseinate
  • 10068, Biochemistry studies - Carbohydrates
  • 10511, Biophysics - Bioengineering
  • light scattering laboratory techniques, spectrum analysis techniques
  • spectrophotometry laboratory techniques, spectrum analysis techniques
  • viscosity measurement laboratory techniques
  • Biomaterials
  • Methods and Techniques


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