大豆分离蛋白影响面团特性的作用机制研究

本文研究了大豆分离蛋白对面团特性的影响规律及其对小麦蛋白的作用机制。结果表明,随着大豆分离蛋白(SPI)添加量的增加,湿面筋含量呈下降趋势,面筋指数呈上升趋势。SPI-小麦面团的吸水率、形成时间、稳定时间和粉质指数逐渐增加,而弱化度逐渐减小。拉伸能量和延伸度逐渐降低,拉伸阻力和拉伸比值逐渐增大。糊化最高黏度、回升值依次降低。总质子信号幅度、T2(1)质子信号幅度、T2(2)质子信号幅度逐渐增大。巯基含量呈上升趋势,二硫键含量呈下降趋势。综合考虑,SPI在面制品中的添加量应低于7%。通过非还原和还原条件下的电泳图,可以看出SPI与小麦蛋白之间确实发生了交联,且SPI与小麦蛋白之间除形成二硫键外,还形成其它共价键。本研究为利用大豆分离蛋白改善面制食品的营养及加工品质,扩大大豆分离蛋白在面制食品加工中的应用范围提供理论基础。

Study on The Mechanism Underlying The Impact of Soy Protein Isolate on Dough Properties

The effects of soy protein isolate (SPI) on dough properties and the mechanism underlying the impact of SPI on wheat protein were investigated in this study. The results showed that as the amount of SPI added gradually increased, the wet gluten content and the gluten index displayed downward and upward trends, respectively. The water absorption rate, development time, stability time, and farinograph quality number of SPI-dough gradually increased, whereas the degree of softness gradually decreased. The tensile energy and extensibility of mixed dough gradually decreased, whereas the resistance to extension and the extension ratio gradually increased. Compared with the control, the peak viscosity and setback of mixed dough decreased upon addition of SPI. The total proton signal amplitude, T2(1) proton signal amplitude, and T2(2) proton signal amplitude gradually increased with SPI addition. The -SH and -S-S- contents gradually increased and decreased, respectively, upon addition of SPI. After comprehensive consideration, the optimum amount of added SPI in flour products should be under 7%. As can be seen from the results of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) under reducing and non-reducing conditions, crosslinking between SPI and wheat protein did occur; in addition to disulfide bonds, other covalent bonds were also observed between SPI and wheat protein. These results provide a theoretical basis for adding SPI to improve the nutritional value and processing quality of flour products and expand the application of soybean protein in the processing of flour-based foods.