Effect of concentration on rheological properties of acid-hydrolyzed amylopectin solutions

Rheological properties are sensitive to variations in molecular structure and they are useful in developing structure–function relationships for systems of polysaccharides in solution. Intrinsic viscosities of acid-hydrolyzed Amioca starches in 90% DMSO/10% water were determined using a modified approach for polyelectrolytes. Double logarithmic plots of specific viscosity, ηsp, against coil overlap parameter, c[η], were made and trends in both the dilute and concentrated regimes were found to be similar to those seen with other polysaccharides. Dynamic frequency sweeps indicated that all acid-hydrolyzed starches in 90% DMSO/10% water exhibited dilute solution or liquid-like behavior with G″ higher than G′. A contradiction in classification of 6–12% starch dispersions was found with shear tests (concentrated) and small strain oscillatory tests (dilute).