Compression of Acid Hydrolyzed Phytoglycogen Nanoparticles at High Packing Densities

Phytoglycogen is a natural polysaccharide produced in the form of compact, 44 nm diameter nanoparticles in the kernels of sweet corn. Its highly branched, dendrimeric structure leads to interesting and useful properties that make the particles ideal as unique additives in personal care, nutrition and biomedical formulations. The properties of phytoglycogen nanoparticles can be altered through chemical modifications such as acid hydrolysis, which not only reduces their diameter but also produces significant changes to the interactions between particles in highly concentrated dispersions. At sufficiently small concentrations (C < 30% w/w), the acid hydrolyzed particles exhibit typical soft sphere behaviour characterized by an increase in the zero-shear viscosity with concentration, reaching a value that exceeds that of water by a factor of ~10³ at C ~ 30% w/w. As the concentration is increased beyond 30% w/w (the concentration at which the particles begin to be compressed against one another), the dependence of zero-shear viscosity versus concentration data shows a pronounced kink, with increases beyond 30% w/w significantly more gradual. This result is consistent with a reduction in stiffness for acid hydrolyzed phytoglycogen nanoparticles.