Impact of polysaccharide molecular characteristics on viscosity enhancement and depletion flocculation

The molecular characteristics (molar mass, hydrodynamic radius, and electrical potential) of gum arabic, corn fiber gum, and beet pectin dissolved in aqueous solutions were measured using size-exclusion chromatography and electrophoresis. Corn fiber gum and beet pectin had extended molecular structures that entrained large quantities of water, whereas gum arabic had a more compact structure. The effectiveness of the polysaccharides at increasing solution viscosity and promoting depletion flocculation decreased in the following manner: beet pectin > corn fiber gum > gum arabic. Mathematical models were used to relate differences in the molar mass and hydrodynamic radius of the polysaccharides to their ability to thicken solutions and promote depletion flocculation. There was good qualitative agreement between the models and experiments, but relatively poor quantitative agreement. The information obtained in this study may be useful for selecting appropriate natural emulsifiers to utilize in emulsion-based products.