The rheological properties were studied of the exopolysac-charides(EPS) produced by a Streptococcus thermophilus strain from Tibetan kefir grain. The results showed that the aqueous EPS solution was a typical non-Newtonian pseudoplastic fluid, and its flow behavior was affected by its concentration, shearing rate, heat treatment, pH and Ca2+. The EPS had good abilities of thickening, its viscosity was 85. 63 mPa·s when concentration was 8. 6 mg/mL. The aqueous EPS solution had pseudoplastic characteristics, its viscosity decreased by 69. 9% when shearing rate increased from 20 to 60 r/min. The EPS is unstable during heat treatment, its viscosity decreased by 74. 4% when temperature rose from 20 to 100 °C , when heated at 60 °C and 80 °C for 150 min individually, its viscosity was influenced to some degrees. The EPS solution at pH 2-6 was relatively stable, while its viscosity at pH 8 and pH 10 greatly increased. The viscosity of EPS decreased markedly with Ca2+ concentration increasing.%以一株西藏灵菇嗜热链球菌为研究对象,系统地研究质量浓度、剪切速率、热处理、pH及盐离子对其所产胞外多糖流变学特性的影响.结果表明,该胞外多糖溶液具有良好的增稠性,质量浓度为8.6 mg/mL时其黏度可达到85.63mPa·s;多糖溶液呈高度假塑性,剪切稀释现象明显；热稳定性差,当温度由20℃升至100℃时,其黏度下降了74.4％,分别于60,80℃热处理150 min,对多糖溶液黏度有不同程度的影响；多糖溶液黏度在酸性条件下相对稳定,但在中性和碱性条件下明显升高；并且随Ca2+浓度升高,多糖溶液黏度显著下降.
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