Rheological properties of a polysaccharide isolated from Adansonia digitata leaves

• The molecular mass of Adansonia digitata polysaccharide was determined as 4.01 × 106 g/mol.
• The polysaccharide macromolecules exhibited random coil conformation in aqueous solution.
• The intrinsic viscosity was 3.27 dL/g.
• The polysaccharide contained uronic acid groups which were confirmed by FTIR.

The rheological properties of Adansonia digitata leaf polysaccharide were studied in dilute and semi-dilute solutions. The intrinsic viscosity of the polysaccharide obtained by Fedors equation and the combined Huggins and Kraemer extrapolations was ∼3.27 dL/g. The polysaccharide contained random coil macromolecules with mass average molecular mass of 4.01 × 106 g/mol. The polysaccharide in semi-dilute concentrations exhibited strong shear thinning property, and viscoelastic behaviour was observed with solutions within (3–5% (w/w)) consistent with the formation of entangled random coil macromolecules in solution. The polysaccharide solutions were sensitive to temperature and the minimum energy to initiate flow in 4.0% polysaccharide solution calculated from Arrhenius plot of zero shear viscosity as a function of temperature was 48.6 kJ/mol. The FTIR spectral studies of the polysaccharide confirmed the presence of uronic acid groups.

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