Analysis of Apparent Viscosity of Aqueous Macromolecule Solutions Containing Sucrose

Abstract

The apparent viscosity (η^a_H) of aqueous macromolecule solutions with and without sucrose was measured. In addition, the apparent reduced viscosity (η^a_red), the intrinsic viscosity ([η]), the dependence of apparent specific viscosity (η^a_sp) on water activity (A_w), and the activation energy of apparent viscosity (E_a) 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 η^a_sp and E_a on A_w, as well as the difference in η^a _red 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.