Polymer-scientific analysis of correlation between the microscopic structure and macroscopic physical properties of foods.

研究了用CaCl2和不加CaCl2制备的热诱导牛血清白蛋白和β-乳球蛋白凝胶中聚集体的分形结构。根据凝胶单轴压缩实验测定的凝胶弹性随浓度的变化关系，利用Shih等人的理论计算了凝胶中聚集体的分维D_f。根据Shih等人的理论，证实了含有CaCl2的凝胶和不含CaCl2的凝胶分别表现出弱键和强键行为。得到强键凝胶的D_f约为2，弱键凝胶的D_f约为2.7。此外，对于含CaCl2(弱连接型)的β-乳球蛋白凝胶，通过对凝胶共聚焦扫描激光显微镜所得凝胶图像的分析，还计算了凝胶的分维，其值与凝胶弹性测量值接近。这些结果表明，聚集体凝胶的弹性行为反映了Ag-…的分形结构。用静态光散射法(SLS)测定了加盐的稀牛血清白蛋白体系中凝聚体的分维D_f。加入氯化钠后，体系呈现出明显的分形结构。D_f值随打浆时间和离子强度的增加而增大。Df值大于传统的簇-簇聚集模型的预测值(Df=1.8或2.1)，这可能是由于聚集过程中团聚体的“重组”所致。另一方面，添加CaCl2的体系没有观察到分形结构。研究了一种典型的离子食品多糖-卡拉胶的介电性质，特别是与其分散体系的溶胶-凝胶转变相关的介电性质。分析了与聚电解质结合的反离子在1 MHz附近的介电弛豫。对于kappa-carrageenan溶液的无序态，介电增量EPsil和驰豫时间tau与聚合物浓度C的关系分别概括为EPSILOnesilon^&lt；oc&gt；C^0和tau^&lt；oc&gt；C^&lt；-1&gt；与聚电解质溶液理论导出的半稀溶液的标度关系一致。对于有序(螺旋态)的kappa-carrageenan分散体系，其介电参数DELTAepsilon和tau的值大于半稀溶液标度方程的预测值。实测值和预测值之间的偏差可以理解为凝胶中螺旋构象缔合的结果。较少

The fractal structure of aggregates in heat-induced BSA and beta-lactoglobulin gels prepared with and without CaCl_2 was examined. From the concentration dependence of the gel elasticity determined from a uniaxial compression test of the gel, the fractal dimensions D_f of the aggregates in the gels were evaluated, using the theory of Shih et al.. It was confirmed that the gels with and without CaCl_2 showed weak-and strong-link behavior in the theory of Shih et al., respectively. The obtained values of D_f were about 2 for strong-link gels and about 2.7 for weal-link gels. In addition, as for the beta-lactoglobulin gels containing CaCl_2 (weak-link type), from the analysis of the gel image obtained with confocal scanning laser microscopy of the gels, the fractal dimensions were also evaluated, the value being close to that evaluated from the gel elasticity measurements. These results indicate that the elastic behavior of the aggregate gels is a reflection of fractal structure of the ag … More gregates in the gels.The fractal dimension D_f of aggregates in dilute BSA system with salt addition was evaluated by static light scattering (SLS). The fractal structure was observed for the system with NaCl addition. The values of D_f increased with increasing beating time and ionic strength. The values of D_f were larger than those (D_f=1.8 or 2.1) predicted by the conventional cluster-cluster aggregation model, probably due to "restructuring" of aggregates during aggregation process. On the other hand, the fractal structure was not observed for the system with CaCl_2 addition.The dielectric properties of a typical ionic food polysaccharide, kappa-carrageenan, were investigated with special relevance to the sol-gel transition of its dispersed system. The dielectric relaxation around 1 MHz due to counterions bound to the polyelectrolyte was analyzed. For the disordered (coil) state of kappa-carrageenan solutions, dependence of the dielectric increment, EPSILONepsilon and that of the relaxation time, tau, on the polymer concentration, C, were summarized as EPSILONepsilon^<oc> C^0 and tau^<oc> C^<-1>, respectively, in good agreement with the scaling relations for the semi-dilute solutions derived from the polyelectrolyte solution theories. For the ordered (helix) state of kappa-carrageenan dispersed systems, the values of the dielectric parameters, DELTAepsilon and tau, were larger than the predicted values using the scaling equations for the semi-dilute solutions. The deviation between the measured and predicted values can be understood as a result of the association of the helical conformers in gels. Less