西藏灵菇发酵乳胞外多糖的流变学特性

Rheological Properties of Exopolysaccharide Produced by Tibetan Kefir

以西藏灵菇发酵乳中分离纯化所得胞外多糖为研究对象,对其流变学特性进行了系统研究。结果表明,该胞外多糖的水溶液表现为典型的非牛顿假塑性流体特性,且其流动行为受胞外多糖的质量浓度、pH值、温度、离子种类和浓度的影响,具体表现为:胞外多糖溶液的黏度随胞外多糖质量浓度的升高而增加,质量浓度越高剪切稀释现象越明显;pH 4.0和pH 10.0时胞外多糖溶液黏度明显低于pH 7.0。Na^+可使胞外多糖溶液的黏度显著增大,且Na^+浓度越高,溶液黏度越大;Ca^(2+)可使胞外多糖溶液的黏度明显下降,但其下降幅度与Ca^(2+)浓度无关;温度在10~85℃范围内胞外多糖溶液的黏度变化很小,有很好的耐温性。加入10 mg/mL的该胞外多糖能够明显增加脱脂乳的黏度。

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 p H 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/m L of the EPS.