Abstract:

In this study, the rheological properties of exopolysaccharide (EPS) produced by Tibetan kefir were evaluated.
The results showed that the aqueous EPS solution was a typical non-Newtonian pseudoplastic fluid, and its flow behavior
was affected by concentration, pH, temperature, cation type and concentration. Specifically, the viscosity of EPS solution
increased with its increasing concentration and the shear thinning phenomenon was more obvious. The viscosity of
EPS solution at pH 10.0 or pH 4.0 was obviously lower than that at pH 7.0. The addition of Na+ significantly increased
the viscosity of EPS solution in a concentration-dependent fashion. However, the viscosity of EPS solution was greatly
decreased when Ca2+ was added. The viscosity of EPS solution little changed with good temperature resistance at 10–85 ℃.
The viscosity of skim milk was significantly increased by adding 10 mg/mL of the EPS.

Key words: Tibetan kefir, exopolysaccharide, rheological properties, steady-state analysis, dynamic oscillatory shear analysis