微波对大豆分离蛋白结构及其膜性能的影响

目的探究微波和离子型表面活性剂处理对大豆分离蛋白结构及其膜性能的影响。方法应用微波以及离子型表面活性剂十二烷基硫酸钠(SDS)对大豆分离蛋白成膜液进行处理,并采用倾倒法成膜。结果微波处理可以使大豆分离蛋白(SPI)紧凑有序的结构在一定程度上舒展,暴露出更多的活性基团,同时,也可以使隐藏于大豆蛋白内部的疏水基团暴露,促进大豆分离蛋白侧链之间形成氢键,与SDS形成疏水键,并产生静电结合,形成空间网络结构。同时,甘油与SPI之间形成的氢键可以使这种结构更加稳定。与对照组相比,经过微波处理的大豆分离蛋白膜具有更高的机械强度以及更好的表面疏水性。当微波功率为400 W时,膜的抗张强度较对照组提高了61.91%,断裂伸长率提高了453.75%,同时,膜也呈现出较好的表面疏水性。结论微波以及离子型表面活性剂处理可以使大豆分离蛋白膜具有更高的力学性能和表面疏水性。

Effects of Microwave on the Structure of Soy Protein Isolate and Its Film-forming Properties

This study aimed to explore the effects of microwave and anionic surfactant sodium dodecyl sulfate (SDS) modification on the structure of soy protein isolate and its film-forming properties. Microwave and SDS were used to treat soy protein isolate (SPI) film-forming solution and films were prepared by casting method. The results demonstrated that microwave treatment led to partial unfolding in the structure of SPI, exposing more reactive groups and the hydrophobic groups hidden inside SPI. This change promoted formation of hydrogen bonds among the side chains of SPI as well as hydrophobic bonds and electrostatic bonds between SPI and SDS, forming cross-linked spatial network structure. Meanwhile, hydrogen bonds formed between glycerol and SPI stabilized this network structure. SPI-based films treated by microwave exhibited higher mechanical properties and better surface hydrophobicity than the untreated ones. Film with microwave treatment at the power of 400 W displayed the highest tensile strength and elongation at break, which were increased by 61.91% and 453.75%, respectively. In addition, these films also showed relatively high surface hydrophobicity. Microwave and SDS modified SPI-based films showed improved mechanical properties and better surface hydrophobicity.