Panouillé Maud, Benyahia Lazhar, Durand Dominique, Nicolai Taco
Polymères, Colloïdes, Interfaces, UMR CNRS, Université du Maine, 72085 Le Mans cedex 9, France.
J Colloid Interface Sci. 2005 Jul 15;287(2):468-75. doi: 10.1016/j.jcis.2005.02.007.
Small micellar casein particles, so-called submicelles, were obtained by removing colloidal calcium phosphate from native casein by adding sodium polyphosphate. Aqueous submicelle suspensions were characterized using light scattering and rheology as a function of concentration and temperature. The casein submicelles behave like soft spheres that jam at a critical concentration (C(c)) of about 100 g L(-1). The viscosity does not diverge at C(c), but increases sharply, similarly to that of multiarm star polymers. C(c) increases weakly with increasing temperature, which leads to a strong decrease of the viscosity close to and above C(c). Concentrated submicelle suspensions show strong shear-thinning above a critical shear rate and the shear stress becomes independent of the shear rate. The critical shear rates at different temperatures and concentrations are inversely proportional to the zero-shear viscosity. At much higher shear rates, the shear stress fluctuates strongly in time indicating inhomogeneous flow. The frequency dependence of casein submicelle suspensions is characterized by elastic behavior at high frequencies (concentrations) and viscous behavior at low frequencies (concentrations).
通过添加多聚磷酸钠从天然酪蛋白中去除胶体磷酸钙，可得到所谓的亚胶粒这种小的胶束状酪蛋白颗粒。使用光散射和流变学方法对亚胶粒水悬浮液进行表征，研究其浓度和温度的函数关系。酪蛋白亚胶粒表现得像软球，在约100 g L⁻¹的临界浓度（C(c)）下会发生堵塞。在C(c)时粘度不会发散，但会急剧增加，类似于多臂星形聚合物的情况。C(c)随温度升高而微弱增加，这导致在接近和高于C(c)时粘度大幅下降。浓亚胶粒悬浮液在临界剪切速率以上表现出强烈的剪切变稀，且剪切应力与剪切速率无关。不同温度和浓度下的临界剪切速率与零剪切粘度成反比。在高得多的剪切速率下，剪切应力随时间强烈波动，表明流动不均匀。酪蛋白亚胶粒悬浮液的频率依赖性表现为在高频（高浓度）下具有弹性行为，在低频（低浓度）下具有粘性行为。
