EGCG与大豆7S/11S蛋白互作对乳液稳定性的影响

Effect of EGCG and Soy 7S/11S Proteins Interaction on Emulsion Stability

以β-伴大豆球蛋白(7S)和大豆球蛋白(11S)为乳化剂,添加表没食子儿茶素没食子酸酯(EGCG)制备O/W型乳液。通过测定复合物三维荧光光谱、热稳定性、粒径分布、ζ-电位及乳液液滴尺寸、色差、液滴形态和界面蛋白吸附等特性,探究EGCG与7S/11S蛋白的相互作用对乳液稳定性的影响。结果表明:EGCG使7S/11S蛋白荧光强度下降,蛋白三级结构展开,热稳定性降低。EGCG引起7S/11S蛋白的交联,使其蛋白颗粒粒径增大,在一定程度上提高ζ-电位。11S蛋白对上述变化更为敏感,提示11S蛋白与EGCG的互作程度强于7S蛋白。添加EGCG提高了两者蛋白乳液的a^(*)、b^(*)值,并显著减小液滴尺寸。当EGCG质量分数为0.02%时,7S/11S蛋白乳液的d4,3最小,而11S蛋白乳液液滴仍以大聚集体形式存在。EGCG明显改善了7S蛋白乳液的储藏分层情况,而对11S蛋白乳液无明显影响。此外,EGCG对7S/11S蛋白乳液界面蛋白整体亚基分布行为没有影响。

In this study,the O/W emulsions have been generated by usingβ-conglycinin(7S)and glycinin(11S)as emulsifiers with adding Epigallocatechin gallate(EGCG).Three-dimensional fluorescence spectrum,thermal stability,particle size andζ-potential of soy protein-EGCG complex,droplet size,chromatic aberration,droplet morphology and interfacial protein adsorption of the emulsion were determined in order to investigate the effects of EGCG interaction with 7S/11S proteins on emulsion stability.The results showed that EGCG decreased the fluorescence intensity of 7S/11S protein,resulting in an unfolding in soy protein tertiary structure and reducing thermal stability.EGCG caused the cross-linking of 7S/11S protein,increasing the particle size of its protein particles,and enhancing itsζ-potential to a certain extent.11S protein was more sensitive to the above changes,suggesting that the interaction between 11S protein and EGCG was stronger than that of 7S protein.The addition of EGCG increased the a^(*) and b^(*) values of both protein emulsions,and significantly reduced the droplet size.When EGCG concentration was up to 0.02%,d4,3 of 7S/11S protein emulsion was the smallest,but 11S protein emulsion droplets still existed in the form of large aggregates.EGCG significantly improved the storage stratification of 7S protein emulsion,but had no significant effect on 11S protein emulsion.In addition,EGCG had no effect on the overall subunit distribution of 7S/11S protein emulsion interface proteins.