Rheological Characteristics and Molecular Weight of Ammonium-Sulfate Fractions of Tara Gum

摘要

This study aimed at characterizing the rheological properties and molecular weight of tara gum fractionated with ammonium sulfate. Tara gum was separated into six fractions (F1-F6) at different concentrations of ammonium sulfate, ranging from 12.21 to28.67% (w/w). The yield of the tara gum fractions ranged between 4.98 and 17.47%, and their intrinsic viscosity ranged from 9.38 to 12.44 dL/g. The highest values of Huggins coefficient (k') and viscosity-molecular mass were observed in fraction F3. Theshear viscosity of the tara gum fractions was measured by a cone-plate viscometer, clearly showing shear thinning behavior. Size-exclusion chromatography results showed that the molecular weight ranged between 635.42 and 776.71 kg/mol, and the F3 fraction exhibited higher values of molecular weight.