The effect of pH, salts and sugars on the rheological properties of cress seed (Lepidium sativum) gum

Effect of shear rate (15-600s(-1)), gum concentration (1-2%), pH (3-9), sucrose (10-40%), lactose (5-15%), NaCl (100-300mm) and CaCl2 (5-50mm) was evaluated on apparent viscosity ((a)), flow behaviour index (n), consistency coefficient (K) and yield stress ((0)) indices of cress seed gum (CSG) solutions. Different rheological models were used to fit the experimental data, although the Herschel-Bulkley model was found the best model. An increase in gum concentration led to an increase in (0), (a), and k and a decrease in n values. The addition of salts lowered the k value; however, the n value showed slight significant change. The presence of sugar resulted in the enhancement of n, k, (0) and (ap) values. The existence of yield stress and pseudoplastic behaviour of CSG, its stability against salts, wide range of pH and synergic effect of sugar make it a good thickener and stabiliser in food formulations.