Abstract：
In order to improve the emulsifying properties of soy protein around isoelectric point, soy protein isolate (SPI) and γ-polyglutamic acid (γ-PGA) complexes were prepared by electrostatic interaction. The formation of SPI-γ-PGA electrostatic complex and emulsifying properties were investigated by monitoring turbidity, zeta potential, intrinsic fluorophores, emulsion characterization, and microstructure observation. The results showed that the formation of SPI-γ-PGA electrostatic complex was identified through turbidimetric analysis and zeta-potential measurement. Intrinsic fluorescence spectrum indicated internal structure changes of electrostatic complexes. Furthermore, SPI-γ-PGA complex-stabilized emulsions showed better stability with small droplet sizes and slow growth as well as the uniform microstructure around the isoelectric point (pH 4.0-5.0) than SPI-formed emulsions. Under the different thermal treatments and ionic strengths, emulsions stabilized by SPI-γ-PGA-soluble complex resulted in improved emulsion stability to environmental stresses. This may be attributed to the increased steric repulsion and electrostatic repulsion by SPI-γ-PGA complexes at oil-water interfaces. The findings derived from this research would provide theoretical reference about SPI-γ-PGA electrostatic complex that can be applied in acid beverages and developed a novel plant-based sustainable stabilizer for emulsions. PRACTICAL APPLICATION: The electrostatic interaction between SPI and γ-PGA improved the emulsifying characteristics of soy protein around isoelectric point. The results derived from this research would expand applications of SPI-γ-PGA-soluble electrostatic complex that can be applied in acid beverages, as well as a novel plant-based sustainable stabilizer for emulsions.
摘要：
为了提高大豆蛋白在等电点附近的乳化性能,通过静电相互作用制备了大豆分离蛋白（SPI）和γ-聚谷氨酸（γ-PGA）复合物。通过监测浊度,研究了SPI-γ-PGA静电复合物的形成和乳化性能,zeta电位,固有荧光团，乳液表征,和微观结构观察。结果表明，通过比浊法分析和ζ电位测量，确定了SPI-γ-PGA静电复合物的形成。本征荧光光谱显示了静电配合物内部结构的变化。此外，与SPI形成的乳液相比，SPI-γ-PGA复合物稳定的乳液显示出更好的稳定性，液滴尺寸小，生长缓慢，等电点（pH4.0-5.0）附近的微观结构均匀。在不同的热处理和离子强度下，通过SPI-γ-PGA可溶性复合物稳定的乳液可改善乳液对环境压力的稳定性。这可能归因于SPI-γ-PGA复合物在油-水界面处的空间排斥和静电排斥增加。这项研究的发现将为SPI-γ-PGA静电复合物在酸性饮料中的应用提供理论参考，并开发了一种新型的基于植物的可持续乳液稳定剂。实际应用:SPI与γ-PGA之间的静电相互作用改善了大豆蛋白在等电点附近的乳化特性。这项研究的结果将扩大SPI-γ-PGA可溶性静电复合物的应用，可应用于酸性饮料，以及一种新型的基于植物的可持续乳液稳定剂。
