Consistency Change of Succinoglycan Aqueous Sodium Chloride Solution during Cooling Process

Abstract

The rheological properties of succinoglycan aqueous sodium chloride solution were investigated at the various temperatures ranging from 30 to 75 °C. The dynamic modulus of the sample solutions abruptly increased at around 65 °C during the cooling process. The critical temperature (T_c) at which the consistency changed sharply depended on the sodium chloride concentration, namely, T_c increased with the salt concentration. Succinoglycan takes a conformation of a semi-flexible single strand chain at above T_c. The spatial size of the polysaccharide at high temperature decreased with the salt concentration since the polysaccharide is a polyelectrolyte. The aqueous solution of the polysaccharide became a structured fluid after the cooling process. To make a quantitative characterization of the mechanical property of the structure fluid, the creep curve analysis was employed. The mechanical properties of the structured fluid can be quantitatively described by using 4- elements mechanical model. Moreover, the effect of the salt on the mechanical properties also emerged. Although the consistency of the sample at above T_c decreased with the salt concentration, it increased with the salt concentration after cooling below T_c. The result revealed that the consistency of the heat denatured succinoglycan aqueous solution was strongly affected with the salt concentration in the system.