Physical properties of food hydrogels on the viewpoint of water state

在食品技术领域，凝胶不仅是食品本身，而且是研究改变分散体系状态的最佳模型。聚合物悬浮液从溶胶状态到凝胶状态的转变不是由化学变化控制的，而是由物理现象引起的。因此，水的分子运动应该被认为是形成凝胶的驱动力，因为水在凝胶中占据了很大的体积。因此，尝试测定了多糖、淀粉和蛋白质悬浮液在凝胶化过程中的物理性质系数。主要研究结果如下：1）为了测量凝胶中水的介电弛豫，制作了一个用于液体样品的实验电极，发现当溶解有具有水的结构形成效应的低分子量化合物如糖时，介电弛豫向长时间一侧移动。溶剂后2)用傅里叶变换流变仪测定了琼脂凝胶在冷却过程中和淀粉在加热过程中溶胶-凝胶转变的机械凝胶点。3)为了防止具有脱水收缩的凝胶的滑动，施加法向力并获得精确的yacoelastic参数。4)虽然不可能测定蛋白质热诱导凝胶化的溶胶-凝胶转变点，但我们成功地获得了准确的数值。5)凝胶化过程中凝胶的力学性能与DSC、热扩散系数等热性能有很好的对应关系。6)这些化合物有助于使水结构防止脱水收缩，并且从凝胶中释放的水服从Pick扩散方程，但味道强度由凝胶的网络密度控制。

In the field of food technology, the gels are not only foods themselves but also best models for investigation of altering the state of disperse system. The transform of polymer suspension through sol to gel state is not governed by chemical change but introduced by physical phenomena. Therefore, the molecular motion of water should be considered as the driving force to form the gel, because water is occupied in gel at large volume. Hence, the coefficients of physical properties of suspensions with polysaccharides, starch and protein during gelation were tried to determine. The results obtained in the present study are as follows ;1) For the measurement of dielectric relaxation of water in the gels, an experimental electrode for liquid sample was made and it was found that the dielectric relaxation was shifted to longer time side when the low molecular weight compounds such as sugar, which has structure-making effects of water, were dissolved in. the solvent. 2) The mechanical gel point for sol-gel transition of agar gels during cooling and starch during heating were determined by Fourier transform Rheometry. 3) T o prevent a slippage of gels which possesses a syneresis, a normal force was applied and obtained the exact yiacoelastic parameters. 4) Although it was impossible to determine the sol-gel transition point of heatinduced gelation of proteins, but we successfully obtained the exact values. 5) The mechanical properties of gels during gelation show the good correspondence with thermal properties such as DSC and thermal diffusivity. 6) The compounds contributed to make a water structure prevent a syneresis and the water release from the gels was obeyed by Pick's diffusion equation but the taste intensity was controlled by the network density of gels.