钙离子对酪蛋白胶束结构影响的光谱学研究

综合运用动态光散射光谱、荧光光谱和高效液相-紫外光谱法检测钙离子对酪蛋白胶束结构的影响。外源添加的钙离子的浓度从0增加至12 mmol·L-1的过程中，酪蛋白胶束的外源ANS荧光强度和浊度一直增大，但是其体积平均直径和胶束的多分散指数是一直下降。同时，当外源添加的钙螯合剂(柠檬酸根)离子的浓度从0 增加至12 mmol·L-1的过程中，酪蛋白胶束的外源ANS荧光强度和浊度一直减小，但是酪蛋白胶束的体积平均直径、胶束的多分散指数和胶束的稳定性是增大的。因此，在对酪蛋白胶束的结构影响方面，钙离子和柠檬酸根离起到了相反的作用。研究证实，外源钙离子可以有效地调节酪蛋白胶束的结构，进而改善其功能特性。

Spectroscopic Investigation of the Influence of Calcium Ion on the Structures of Casein Micelles

The effects of calcium ion on the structural properties of casein micelles in the course of heat treatment were synthetically examined by non-structure-invasive spectrometry. The hydrophobicity, reflected by extrinsic fluorescence (ANS fluorescence), was positively correlated with the concentration of the calcium ion, within the range of 0 to 12 mmol·L-1. Meanwhile, the turbidity and stability of casein micelles also increased with the growth of calcium concentrations. However, opposite results were observed for hydrodynamic diameter and polydispersity index. Compared with the calcium ion, the calcium-chelator (citrate) has an opposite effect on the structural characteristics of casein micelles. Within the calcium concentrations range of 0 to 12 mmol·L-1, the hydrophobicity, stability and turbidity were negatively correlated with the concentration of the calcium ion, nevertheless, opposite results were observed for hydrodynamic diameter and polydispersity index. All the results indicate that the calcium ion could be used to modify the structures of casein micelles during heat heatment.