大豆分离蛋白与寡糖静电相互作用及复合物乳化性的分析

以大豆分离蛋白（soybean protein isolate，SPI）和寡糖（棉子糖和水苏糖）为原料制备复合溶液，通过调节pH值（3.0～10.0）研究SPI-寡糖形成复合体系的相行为、微观结构，确定形成可溶性静电复合物的条件及其对蛋白质溶解性、乳化性的影响。Zeta电位、激光共聚焦显微镜观测和浊度测定的结果显示，在酸性条件下，SPI与寡糖通过静电相互作用形成复合物，且等电点与SPI相比向酸性偏移；内源荧光光谱扫描发现SPI-寡糖复合物的荧光强度低于SPI，且静电相互作用越强荧光强度降低越明显。当pH?6.0时，SPI-寡糖较大程度形成可溶性静电复合物，此时复合物的功能性质较SPI有所改善，SPI-水苏糖和SPI-棉子糖的乳化性与SPI相比分别提高了50.66%和39.69%。

Electrostatic Interaction of Soybean Protein Isolate with Oligosaccharide and Emulsifying Capacity of Their Complexes

In this paper, soybean protein isolate (SPI) and oligosaccharides (raffinose and stachyose) were used to prepare a mixed aqueous solution. The phase behavior and microstructure of the composite system were studied at varying pH from 3.0 to 10.0 in order to determine the generation conditions of soluble electrostatic complex and its influence on the emulsifying properties of SPI. The results of zeta potential, confocal laser scanning microscope and turbidity measurement showed that SPI and oligosaccharides could form an electrostatic complex under acidic conditions. Moreover, the isoelectric point of the complex shifted toward acidity compared to SPI. The intrinsic fluorescence spectra illustrated that the fluorescence intensity of the complex was lower than that of SPI, and it showed a more significant decrease with stronger electrostatic interaction. This research also indicated that SPI and oligosaccharides could form soluble electrostatic complexes at pH 6.0, whose functional properties were improved compared to SPI. The emulsifying capacity of SPI-stachyose and SPI-raffinose complexes were increased by 50.66% and 39.69% compared to that of SPI.