Erwinia (E) gum

an extracellular polysaccharide

is composed of fucose

galatose

glucose andglucuronic acid. Its viscosity behavior was investigated by a low-shear-rate multiball viscometer and arotational viscometer. Its weight-average molecular weight Mw and intrinsic viscosity [η] in 0.2 mol/L NaClaqueous solution were measured by light scattering method at 35℃ and viscometry at 25℃ and found to be1.06×106 g/mol and 1050 mL/g

respectively

and its aggregates in aqueous solution were proved by gel permeation chromatography (GPC).These results indicated that E gum in water has exceedingly high viscosity and exhibiys Binham fluid behavior

owing to its aggregation.The viscosity of E gum decreased with increasing temperature

and the turning point appeared at 38℃ for dilute solution and 80℃ for concentrated solution suggesting that the affregates of E gum in water started to disaggregate under these temperatures.In addition

the aggregates can be disrupted by adding either acid or base.The experimental results indicated that the E gum is a good thickening agent

and its fluid behavior is similar to xanthan.