基于动态流变学的明胶/变性淀粉共混体系 溶胶-凝胶相互转变动力学解析. (Chinese)

To explore the mechanism of the sol-gel transition of gelatin (GL)/modified starch (MS) blends in glucose syrup (GS) cosolute system, the evolving trend of viscoelastic modulus (G’ and G”) and the transition kinetics were investigated by dynamic rheology. Based on the first and second order derivatives of G’ versus t curves, there existed four characteristic temperatures for sol-gel (T ig , T g , T cg and T mg ) and gel-sol (T is , T cs , T s and T ms ) transition either separately, correspondingly dividing the phase transition process into five stages. During the phase transition process, the existing state of gelatin molecules was determined by these characteristic temperatures. With the increase of GS concentration (0%–60%, m/m), the initial sol-gel phase transition temperature (T ig ) and gel point temperature (T g ) were increased, and the gel strength of GL/MS blend was decreased significantly. However, there was a downward trend in the sol point temperature (T s ). The activation energy (E a ) value of the phase transition process in the high temperature zone were decreased firstly and then increased with the increase of GS concentration, while the Ea value in the low temperature zone was not changed significantly. These results could provide a theoretical basis for the process optimization and quality control of GL/MS blend gel products. [ABSTRACT FROM AUTHOR]

为探究葡萄糖浆共溶质对明胶/变性淀粉共混体系溶胶-凝胶相转变机制，采用动态流变仪研究共混体系弹 性模量（G’）、损耗模量（G”）演变趋势及动力学行为。对相转变G’-t曲线求一阶及二阶导数，发现分别有4 个特 征温度存在于溶胶-凝胶（Tig、Tg、Tcg及Tmg）及凝胶-溶胶（Tis、Tcs、Ts及Tms）转变过程，将对应相转变过程分为 5 个阶段，各特征温度主要影响明胶高分子的存在状态。随葡萄糖浆质量分数（0%～60%）增加，溶胶-凝胶相转 变起始温度（Tig）及凝胶点温度（Tg）呈升高趋势，同时明胶/变性淀粉共混凝胶强度明显降低，凝胶-溶胶相转变 溶胶点温度（Ts）呈下降趋势，相转变过程高温区活化能（Ea）呈先降低后增加趋势，低温区Ea则无明显变化。本 研究结果可为明胶/变性淀粉共混凝胶产品工艺优化及质量控制提供理论参考。 [ABSTRACT FROM AUTHOR]

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