pH值对酪蛋白-葡聚糖共聚物胶束结构和性质的影响

酪蛋白胶束是天然的纳米输送系统，通过美拉德反应获得的酪蛋白-葡聚糖共聚物可解决酪蛋白胶束在等电点pH值范围内溶解性和乳化性低的问题。采用荧光光谱和动态激光光散射等手段研究经超滤分离的酪蛋白-葡聚糖共聚物的聚集行为及其与pH值的关系。结果表明：酪蛋白-葡聚糖共聚物在酪蛋白质量浓度大于0.4 mg/mL时开始自组装形成胶束，形成胶束的结构具有pH值依赖性。相比于其他pH值条件，等电点附近共聚物胶束的结构最为致密且稳定性良好，空间位阻效应是维持其稳定的主要原因。乳化性质则表明，等电点附近的酪蛋白共聚物胶束的乳化活性和乳化稳定性分别提高了2.17 倍和3.33 倍。因此，酪蛋白-葡聚糖共聚物胶束对环境pH值的响应性可为其在营养素纳米载体领域的应用提供更加多样化的选择。

Effect of pH on the Structure and Property of Casein-Dextran Conjugate Micelles

Casein micelle, as a natural nano-capsular vehicle for nutraceuticals, has the properties of low solubility andemulsifying ability at pH near the isoelectric point. Casein-dextran conjugates via Maillard reaction are expected toovercome these problems. In this work, the aggregation behavior and pH dependence of casein-dextran conjugates separatedthrough ultrafiltration were explored by using fluorescence spectroscopy and dynamic light scattering. The results showedthat casein-dextran conjugates began to self-assemble when the concentration of casein exceeded 0.4 mg/mL. The conjugatedmicelles had a compact structure or a relatively loose structure under different pH conditions. The structures of micelles atpH near the isoelectric point were the most compact, and presented a good stability due to the steric hindrance. Meanwhile,the emulsifying activity and emulsion stability of the conjugated micelles were increased by 2.17 and 3.33 times at pH nearthe isoelectric point, respectively. Therefore, the pH dependence of casein-dextran conjugate micelles might provide morechoices for their use in the field of nutraceutical nanocarriers.