Rheological and thermal studies on gelling characteristics of curdlan

Viscoelastic properties of curdlan gels and its aqueous suspensions of vari ous concentrations were investigated by creep tests and oscillatory dynamic experiments to analyze its gelling characteristics. Temperature dependence of viscoelasticity of the curdlan gel suggested that with increasing heati ng temperature, interactions between curdlan molecules, forming a three-dim ensional network, became stronger and the number of elastically active chai ns increased, which made the gel more elastic or solid-like. It also sugges ted that the transition temperature from thermo-reversible to irreversible gel was concentration-dependent. Increase in concentration lowered the irre versible-gel formation temperature from the generally reported 80 degrees C and decreased the amount of the thermo-reversible component in the gel. Re sults from both differential scanning calorimetry analyses and thermal scan ning rheological measurements of curdlan supported this, suggesting that in crease in concentration promoted hydrophobic interactions between the molec ules at a lower temperature than at 80 degrees C, which contributed to the thermo-irreversibility of the gel. (C) 1999 Elsevier Science Ltd. All right s reserved.