丁酰化淀粉在ZnCl2溶液中解构过程的流变学特性

Rheological Properties of Butyrylated High Amylose Corn Starch During Deconstruction in Zinc Chloride Solution

为改善丁酰化直链淀粉(BS)机械加工性能,拟对比酰化和未酰化淀粉在ZnCl_(2)溶剂中的微观解构形态,并通过旋转流变仪考察BS浓度、温度和ZnCl_(2)浓度对BS-ZnCl_(2)稀溶液的剪切流变特性和幂律模型的影响。结果表明,BS完全解构的最低ZnCl_(2)溶液浓度为30.7%,低于高直链玉米淀粉HACS的最低ZnCl_(2)溶液浓度(41.9%),且BS完全崩解,而HACS仍保留少量淀粉颗粒;所有样品的黏度-剪切速率曲线符合剪切稀化的假塑性流体特点,根据Power Law模型能够将BS-ZnCl_(2)水溶液分为稀化和黏稠状态,且流体的链相互作用和结构特性存在明显的溶质溶剂浓度依赖性,并得出流变特征指数n的多元一次线性拟合公式,根据各自变量系数绝对值可知影响流体表观黏度的强弱顺序为BS浓度>ZnCl_(2)浓度>温度,将任意因子参数代入公式即可预测其特征指数n。说明ZnCl_(2)溶液能够作为改善酰化淀粉生物活性和功能价值的均相介质。

In order to improve the machinability of butyrylated amylose(BS),the microscopic deconstructed morphologies of acylated and unacylated starches in zinc chloride were compared,and the effects of BS concentration,temperature and ZnCl_(2)concentration on shear rheological properties and power law model of BS-ZnCl_(2)dilute solution were investigated by rotating rheometer.The results show that the minimum ZnCl_(2)concentration for complete deconstruction of BS is 30.7%,which was lower than the minimum ZnCl_(2)concentration(41.9%)for high amylose corn starch(HACS),and BS is completely disintegrated,while HACS still retains a small amount of starch granules.The viscosity-shear curve of all samples conforms to the characteristics of shear-thinning pseudoplastic fluids.According to the power Law model,the BS-ZnCl_(2)aqueous solution can be divided into thinning and viscous states,and the chain interaction and structural properties of the fluid have obvious solute solvent concentration dependencies,and the multivariate linear fitting formula of the rheological characteristic index n is obtained.According to the absolute value of each variable coefficient,it can be seen that the order of affecting the apparent viscosity of the fluid was BS concentration>ZnCl_(2)concentration>temperature.Bring any factor parameter into the formula,characteristic index n can be predicted.It shows that ZnCl_(2)solution can be used as a homogeneous medium to improve the biological activity and functional value of acylated starch.