Effect of temperature, ion type and ionic strength on dynamic viscoelastic, steady-state and dilute-solution properties of Descurainia sophia seed gum

In this study, dilute solution, steady state and dynamic rheological properties of Descurainia sophia seed gum (DSSG) were investigated. With increasing the solution temperature, the intrinsic viscosity and coil dimension of DSSG decreased. The intrinsic viscosity of DSSG was essentially constant over a very extensive range of ion concentrations. Activation energy and chain flexibility of DSSG were found to be 1.1 x 10(7) (J/kg) and 1353 (1/K), respectively. DSSG can be introduced as good encapsulator in food and pharmaceutical systems due to low degree of chain flexibility. Steady shear measurements showed shear thinning behavior at all tested temperatures, regardless of ion type and ionic strength. Addition of NaCl and increasing temperature caused a decrease in consistency coefficient and an increase in the flow behavior index. On the other hand, at high CaCl2 concentration, the consistency coefficient of DSSG increased. The values of tan delta in all tested conditions were lower than one, but more than 0.1, revealing weak gel-like behavior. The frequency sweep results revealed that DSSG solution had weak gel behavior at different ions types and ionic strengths: as dynamic moduli increased with increasing frequency and G' was always superior to G ''. The data obtained in the present study and the results thereof can be useful when considering the impact of salts, and/or processing parameter such as temperature on food systems. (C) 2017 Elsevier Ltd. All rights reserved.