花青素与大豆分离蛋白非共价/共价作用对其界面功能性质的影响

Effects of Non-Covalent/Covalent Interactions between Anthocyanins and Soybean Protein Isolate on Its Interfacial Function

采用三维荧光光谱法研究不同质量浓度花青素与大豆分离蛋白间的复合程度,采用起泡特性及起泡稳定性测定、乳化特性及乳化稳定性测定、光学显微镜观察分析、巯基含量测定等方法,重点解析非共价结合/共价交联方式下蛋白质-花青素复合体系结构变化与功能性质间的关系。结果表明:在pH 7.4、2 h和pH 9.0、24 h处理条件下,随着花青素质量浓度的增大,复合物中蛋白特征峰荧光强度降低,蛋白质多肽链解折叠,共价结合能力强于非共价结合能力。复合液中蛋白的起泡特性及起泡稳定性、乳化特性及乳化稳定性均有提高,巯基含量下降,其中在pH 9.0、24 h条件下,6号样品表现尤为明显。样品5、6乳液体系中乳滴大小均一、分散均匀、乳液稳定。

The aim of this study was to compare the effects of different concentrations of anthocyanins on the functional properties of proteins through non-covalent/covalent interactions.The complexes of anthocyanins and soybean protein isolate(SPI)were studied by three-dimensional fluorescence spectroscopy.The relationship between the structural changes of protein-anthocyanin complexes and protein functional properties with non-covalent/covalent interactions was analyzed by determination of emulsifying properties and foaming properties,light microscope observation and measurement of sulfhydryl content.The results showed that the fluorescence intensities of the characteristic peaks of the proteins decreased,accompanied by the occurrence of unfolded polypeptide chains,with the increase of anthocyanin concentration after treatment at pH7.4for2h or at pH9.0for24h,and the covalent binding was stronger than the non-covalent one.The emulsifying properties and foaming properties of the complexes were improved as compared with SPI,and the content of sulfhydryl group was decreased,especially for sample6(treatment with2mg/mL anthocyanins at pH9.0for24h).The droplet sizes of emulsion systems5(with1mg/mL anthocyanins at pH9.0for24h)and6were homogeneous,and the emulsions were stable.