Analysis of apparent viscosity of aqueous macromolecule solutions containing sucrose

Abstract

The apparent viscosity (ηaH) of aqueous macromolecule solutions with and without sucrose was measured. In addition, the apparent reduced viscosity (ηared), the intrinsic viscosity ([η]), the dependence of apparent specific viscosity (ηasp) on water activity (Aw), and the activation energy of apparent viscosity (Ea) were analyzed to compare the inter-macromolecular interactions among six aqueous macromolecule solutions at a fixed concentration. The macromolecule solutions tested were 2% polyethylene glycol (PEG35000, MW = 35 kDa), dextran (DexT40, MW = 40 kDa), apple pectin, citrus pectin, sodium alginate, and 0.5% xanthan. Based on the dependence of ηasp and Ea on A w, as well as the difference in ηared and its relationship with [η], the apparent viscosity behavior of the macromolecule solutions tested was classified into three groups. In Group A which consists of PEG35000 and DexT40, the macromolecules are diluted enough such that intermolecular interactions are very weak. In Group B which consists of pectins and alginate, the macromolecules are in contact with one another such that inter-macromolecular interactions become stronger and the addition of sucrose affects the macromolecular interactions. In Group C which consists of xanthan, macromolecular chains are physically entangled with partial aggregations such that inter-macromolecular interactions are very strong, but the addition of sucrose has almost no effect on the interaction.