Comparative heterogeneity, molecular weights and viscosities of xanthans of different pyruvate and acetate content
Özet
Introduction: The bacterial exopolysaccharide xanthan is a well-known hydrocolloid, with a high viscosity deriving from its large molecular weight and volume.
Materials and methods: Four different xanthans deriving from Xanthomanas campestris e two with
similar pyruvate and acetate contents and two with different contents e were characterized in dilute
aqueous buffered solution (pH 7.0, ionic strength 0.3 M) using sedimentation velocity and sedimentation
equilibrium in the analytical ultracentrifuge, supplemented by dynamic light scattering.
Results: This facilitated a comparison with regards heterogeneity (sedimentation coefficient distribution)
and molecular weight, despite their large size and low critical overlap concentration. The xanthans were
also compared with regard to reduced specific and intrinsic viscosity behaviour. The xanthans generally
show strong similarity in properties with the exception of the lowest pyruvate xanthan, a finding which
should be useful for future applications of these materials.