Time-dependent (thixotropic) rheological behavior of sage seed gum in the presence of some salts and sugars

In this study, the time-dependent (thixotropic) rheological behavior of sage seed gum (SSG) dispersions in the presence of NaCl and CaCl2 salts (0, 10, 50 and 100 mM), and glucose and sucrose sugars (0%, 2%, 4% and 6%) at different shear rates (10-50 s-1) was investigated. SSG dispersions exhibited a thixotropic behavior at all the conditions examined. The data obtained from rheological measurements were fitted well to the second-order structural kinetic (SOSK) model for salt solutions (R2 = 0.918-0.987, RMSE = 0.003-0.017) and Weltman model for sugar solutions (R2 = 0.921-0.993, RMSE = 0.003-0.020). The structural breakdown rate (k) and the structural breakdown extent (0/) values obtained for SSG in CaCl2 solutions were greater and lower than those of NaCl, respectively. Among the salt solutions, the SSG dispersions containing 10 mM NaCl have the greatest initial shear stress (A) and time coefficient of thixotropic breakdown (B) values. The chain stiffness (S) value in the presence of Ca2+ (8×10-4 ̶ 12×10-4 M0.5.Pa.s) was greater than that of Na+ (6×10-4 ̶ 8×10-4 M0.5.Pa.s). For sugar solutions of SSG, the greatest value of k was obtained for sucrose and the 0/ parameter diminished with increasing shear rate. Sugar concentration had a direct and indirect relationships with A and B parameters, respectively. The results of current study revealed that the thixotropic behaviour of SSG solutions is remarkably influenced by the salts and the sugars, so this issue can be considered in food product processing.