Han Mei, Du Chao, Xu Zhi-Yuan, Qian He, Zhang Wei-Guo
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, JiangNan University, 1800# Lihu Road, Wuxi-214122, JiangSu Province, China; State Key Laboratory of Dairy Biotechnology, Technology Center Bright Dairy & Food Co., Ltd., Shanghai 200436, China.
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, JiangNan University, 1800# Lihu Road, Wuxi-214122, JiangSu Province, China.
Int J Biol Macromol. 2016 Jul;88:603-13. doi: 10.1016/j.ijbiomac.2016.04.035. Epub 2016 Apr 22.
The exopolysaccharide (EPS) produced by Sporidiobolus pararoseus JD-2 contained about 2.0% phosphorus and its zeta potential was -30mV at pH 6.0. This indicated that it was an anionic polymer. In steady shear measurements, there was a Newtonian plateau in low shear rates, but power-law behavior exhibited at high shear rates. So Williamson model was used to study the flow character of the EPS solutions. This phenomenon was according to its high molecular weight and entanglement networks. Considering the EPS was an anionic polymer, the influence of added salts on apparent viscosity of EPS were studied. Different NaCl concentrations had little effect on the viscosity of the EPS, but high concentrations of CaCl2 increased the viscosity of EPS significantly. EPS solutions showed inapparent thixotropic properties in stress growth and thixotropic loop experiment. According to the flow curve results and oscillatory shear results obtained, the rheological properties of EPS solutions were closer to that of entanglement network system, like carboxy methyl cellulose rather than weak gel structure such as xanthan gum. The EPS had the function to enhance immunological functions. Understanding the rheological characteristics of EPS was essential to exploit the functionality of this EPS in different food or medicine systems.
嗜玫色掷孢酵母JD-2产生的胞外多糖（EPS）含有约2.0%的磷，其在pH 6.0时的ζ电位为-30mV。这表明它是一种阴离子聚合物。在稳态剪切测量中，低剪切速率下存在牛顿平台，但在高剪切速率下表现出幂律行为。因此，采用威廉姆森模型研究EPS溶液的流动特性。这种现象归因于其高分子量和缠结网络。考虑到EPS是一种阴离子聚合物，研究了添加盐对EPS表观粘度的影响。不同浓度的NaCl对EPS的粘度影响不大，但高浓度的CaCl2显著增加了EPS的粘度。在应力增长和触变环实验中，EPS溶液表现出不明显的触变特性。根据得到的流动曲线结果和振荡剪切结果，EPS溶液的流变特性更接近缠结网络体系，如羧甲基纤维素，而不是像黄原胶那样的弱凝胶结构。EPS具有增强免疫功能的作用。了解EPS的流变特性对于在不同食品或医药体系中开发这种EPS的功能至关重要。
