Bindal Aditya, Narsimhan Ganesan, Hem Stanley L, Kulshreshtha Alok
Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA.
Pharm Dev Technol. 2007;12(2):159-67. doi: 10.1080/10837450701212545.
Steam sterilization of xanthan gum solutions at 121 degrees C caused a decrease in the helix conformation as well as the molecular weight distribution with a corresponding increase in the coil structure. The effect was directly related to the exposure time and inversely to the xanthan gum concentration, thus suggesting a two-step mechanism of disentanglement followed by degradation with the first step being predominant at higher concentrations. Mark-Houwink exponent of 0.9002 for the intrinsic viscosity of xanthan gum compared favorably with reported values in the literature. The model for intrinsic viscosity of a free draining coil yielded an expansion coefficient of 1.2 (independent of molecular weight) and a root mean square radius of unperturbed chain in the range of 189.5-368 nm. The root mean square unperturbed chain length increased with molecular weight without reaching an asymptotic value, thus indicating that the xanthan molecule behaved as a stiff chain.
在121摄氏度下对黄原胶溶液进行蒸汽灭菌会导致螺旋构象减少以及分子量分布变化，同时线圈结构相应增加。这种影响与暴露时间直接相关，与黄原胶浓度成反比，因此表明存在两步解缠机制，随后是降解，第一步在较高浓度下占主导。黄原胶特性粘度的Mark-Houwink指数为0.9002，与文献报道值相符。自由排水线圈特性粘度模型得出膨胀系数为1.2（与分子量无关），未受干扰链的均方根半径在189.5 - 368纳米范围内。未受干扰链的均方根长度随分子量增加但未达到渐近值，因此表明黄原胶分子表现为刚性链。
