pH偏移结合加热处理对大豆分离蛋白结构特性的影响

The Effect of p H-Shifting Combined with Heating Treatment on Structural Properties of Soybean Protein Isolate

探讨了p H偏移结合加热处理对大豆分离蛋白结构特性的影响。将大豆分离蛋白经酸性条件(p H 1.5)结合加热(50和60℃)处理0,1,3,5 h,然后恢复到中性条件,测定处理前、后大豆分离蛋白的总巯基和活性巯基以及紫外二阶光谱、色氨酸内源荧光光谱和蛋白电泳的变化。研究结果表明,p H 1.5偏移结合加热处理条件,大豆分离蛋白的总巯基和活性巯基含量显著下降(P<0.05),其随时间的变化不显著(P>0.05)。紫外扫描和色氨酸荧光分析表明大豆分离蛋白的二级和三级结构发生改变,暴露出更多的疏水基团。SDS-PAGE电泳表明,大豆分离蛋白产生了非二硫键的共价聚集。p H偏移结合加热处理在一定程度上改变了大豆分离蛋白的结构特性。

This study mainly investigated the changes of structural properties of soybean protein isolate（SPI） induced by p H shifting combined with heating treatment. SPI was treated 0, 1, 3, 5 h by acidic p H shifting（p H 1.5） combined with heating（50 ℃ and 60 ℃） treatment, followed by refolding at neutral p H. The total sulfhydryl and reactive sulfhydryl content, UV-Vis spectra and tryptophan fluorescent emission spectrum were investigated. The results revealed that the total sulfhydryl and reactive sulfhydryl content had significant decrease（P〈0.05）, but there is no significant change as time extending, while tryptophan fluorescent emission spectrum and UV-Vis spectra showed that second and third structures were changed and more hydrophobic groups were exposed. The SDS-PAGE patterns showed that non-disulphides linkage between proteins was produced by protein aggregation. These results showed that structural characteristics of SPI were changed via p H shifting combined with heating treatment.