Dynamic viscoelasticity of curvielan

a novel gel-forming exopolysaccharide produced by soil bacterium Alcaligenes sp.Q9415 was studied.Over the angular frequency (ω) range 0.01～100rad·s-1

the storage modulus ( G′) of 1.4% (W/W) curvielan gels was much higher than its loss modulus (G″) and less dependent on frequency which showed that curvielan had fine elasticity.0.5% was close to the threshold concentration needed for gelation.Curvielan was dispersible in cold water to form weak gel which could become much strong viscoelastic gel at about 90℃ for 10min.Continuous heating at high temperature and freezing-thawing treatment damaged the network of curvielan gel.Similar results were observed for curvielan gels prepared under pH3 and 10.Addition of 1%～18% NaCl

6% KCl

CaCl2

MgCl2

Zncl2and 20% sucrose decreased the G' of 1% curvielan gel at low frequency and increased G″ over the frequency range 0.01～100rad·s-1 which indicated that the formation of elastic network was hindered.However

addition of 6% AlCl3 of FeCl3 made total loss of viscoelasticity of the 1% urvielan system.