Wan Zhili, Yang Xiaoquan, Sagis Leonard M C
Research and Development Center of Food Proteins, Department of Food Science and Technology, South China University of Technology , Guangzhou 510640, People's Republic of China.
Laboratory of Physics and Physical Chemistry of Foods, Wageningen University , Bornse Weilanden 9, 6708WG Wageningen, The Netherlands.
Langmuir. 2016 Apr 19;32(15):3679-90. doi: 10.1021/acs.langmuir.6b00446. Epub 2016 Apr 11.
The surface and foaming properties of native soy glycinin (11S) and its heat-induced fibrillar aggregates, in the presence of natural surfactant steviol glycoside (STE), were investigated and compared at pH 7.0 to determine the impact of protein structure modification on protein-surfactant interfacial interactions. The adsorption at, and nonlinear dilatational rheological behavior of, the air-water interface were studied by combining drop shape analysis tensiometry, ellipsometry, and large-amplitude oscillatory dilatational rheology. Lissajous plots of surface pressure versus deformation were used to analyze the surface rheological response in terms of interfacial microstructure. The heat treatment generates a mixture of long fibrils and unconverted peptides. The presence of small peptides in 11S fibril samples resulted in a faster adsorption kinetics than that of native 11S. The addition of STE affected the adsorption of 11S significantly, whereas no apparent effect on the adsorption of the 11S fibril-peptide system was observed. The rheological response of interfaces stabilized by 11S-STE mixtures also differed significantly from the response for 11S fibril-peptide-STE mixtures. For 11S, the STE reduces the degree of strain hardening in extension and increases strain hardening in compression, suggesting the interfacial structure may change from a surface gel to a mixed phase of protein patches and STE domains. The foams generated from the mixtures displayed comparable foam stability to that of pure 11S. For 11S fibril-peptide mixtures STE only significantly affects the response in extension, where the degree of strain softening is decreased compared to the pure fibril-peptide system. The foam stability of the fibril-peptide system was significantly reduced by STE. These findings indicate that fibrillization of globular proteins could be a potential strategy to modify the complex surface and foaming behaviors of protein-surfactant mixtures.
在pH 7.0条件下，研究并比较了天然大豆球蛋白（11S）及其热诱导纤维状聚集体在天然表面活性剂甜菊糖苷（STE）存在时的表面和发泡特性，以确定蛋白质结构修饰对蛋白质 - 表面活性剂界面相互作用的影响。通过结合滴形分析张力测定法、椭偏仪和大振幅振荡拉伸流变学，研究了气 - 水界面的吸附以及非线性拉伸流变行为。利用表面压力与变形的李萨如图形，根据界面微观结构分析表面流变响应。热处理产生了长纤维和未转化肽的混合物。11S纤维样品中存在小肽导致吸附动力学比天然11S更快。STE的添加显著影响11S的吸附，而对11S纤维 - 肽体系的吸附未观察到明显影响。由11S - STE混合物稳定的界面的流变响应也与11S纤维 - 肽 - STE混合物的响应显著不同。对于11S，STE降低了拉伸时的应变硬化程度，增加了压缩时的应变硬化程度，表明界面结构可能从表面凝胶转变为蛋白质斑块和STE域的混合相。混合物产生的泡沫显示出与纯11S相当的泡沫稳定性。对于11S纤维 - 肽混合物，STE仅显著影响拉伸响应，与纯纤维 - 肽体系相比，应变软化程度降低。STE显著降低了纤维 - 肽体系的泡沫稳定性。这些发现表明，球状蛋白质的纤维化可能是改变蛋白质 - 表面活性剂混合物复杂表面和发泡行为的一种潜在策略。
