Rheological properties of Triumfetta cordifolia gum solutions in the concentrated regime

• Published in: International journal of biological macromolecules 2024-11, Vol.279 (Pt 2), p.135335, Article 135335
• Main Authors: Fanwa, Michèle N., Hucher, Nicolas, Cheumani, Arnaud M.Y., Ndikontar, Maurice K., Malhiac, Catherine, Grisel, Michel
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Hydrogen-Ion Concentration; Plant Gums - chemistry; Rheology; Salt and pH effects; Solutions; Temperature; Triumfetta Cordifolia gum; Viscosity
• ISSN: 0141-8130; 1879-0003; 1879-0003
• DOI: 10.1016/j.ijbiomac.2024.135335

The polyelectrolyte gum from Triumfetta cordifolia stem bark has recently come to the fore for its remarkable potential as an emulsifier and stabilizer for aqueous formulations. This paper presents the rheological study of T. cordifolia gum aqueous solutions in the concentrated regime (C > C** = 0.14 % w/w). To this end, both flow and oscillation tests were performed on T. cordifolia gum solutions at two distinct concentrations belonging to the concentrated regime: at 0.2 % w/w (close to C**) and at 0.7 % w/w (far above C**). The effect of temperature, pH and added salts (NaCl, CaCl2 and AlCl3) on gum viscoelastic parameters were investigated, revealing associative interactions. Under specific conditions, several remarkable and complex phenomena were observed, such as over-structuring induced by temperature, anti-thixotropy, gelation, syneresis and salting-out induced by salt addition. The charged structure of T. cordifolia gum (weak polyelectrolyte), the high divalent metal content and the presence of associative groups in its network were demonstrated as the major factors responsible for these phenomena. These findings form the basis for the structure-property relationships of T. cordifolia gum and may open up to further investigations for this gum of great potential in many fields of applications. [Display omitted] •Concentrated solutions (C ᐳ C**) of the anionic T. cordifolia gum were studied.•In aqueous media, T. cordifolia gum forms pseudoplastic solutions with weak gel behavior.•T. cordifolia gum solutions exhibit both shear-and temperature-induced associations.•Gelation and syneresis occur on direct addition of the trivalent salt AlCl3.•Under dialysis, the addition of salts (NaCl, CaCl2 or AlCl3) causes salting-out.