Rheological properties of β-d-glucan from the fruiting bodies of Ganoderma lucidum

• New β-(1,3)-d-glucan from Ganoderma l.: high Mw, high purity.
• Unique steady shear flow behavior.
• Viscoelastic characteristics and weak gel structures.

Rheological properties of a β-(1,3)-d-glucan (GLP20) from the fruiting body of Ganoderma lucidum in water at different concentrations were studied with a strain controlled ARES Rheometer at 25 °C. The intrinsic viscosity was measured by Ubbelohde viscometer and estimated to be 1248.05 mL/g from the mean of both intercepts by plotting ηsp/c and lnηrel/c against concentration. Shear-thinning behavior occurred at lower concentrations and very low critical shear rates. The zero shear specific viscosity (ηsp,0) was plotted against the coil overlap parameter (c[η]) and the slopes of the lines in the dilute and semi-dilute regimes were found to be 1.23 and 4.19, respectively. The critical concentration (c∗) was determined to be about 0.79 g/L, which was much lower than that of general disordered polymers. This may be due to the stiff chain conformation of GLP20. The results from dynamic experiments revealed that GLP20 in pure water displayed liquid-like behavior at low concentrations (≤0.5%) and could form weak gels with the increase of concentration.

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