紫花芸豆蛋白体外消化产物的抗氧化活性及结构特征分析

为探究芸豆蛋白在体外模拟胃部消化期间抗氧化活性及结构特征，本实验以紫花芸豆蛋白为原料，采用体外模拟消化模型，并运用多种蛋白分析方法进行检测。结果表明：在消化期间因酶解作用，其水解度及溶解度明显提高，并且随着芸豆蛋白低分子质量肽段数量的增加，消化产物的抗氧化活性显著增加，其中总抗氧化能力、铁离子还原能力分别提高了296.97%、54.01%；通过傅里叶变换红外光谱分析发现，消化过程使芸豆蛋白二级结构发生显著变化，随消化时间的延长，消化产物中α-螺旋相对含量、β-转角相对含量不断提高，β-折叠相对含量不断降低；经模拟消化后的芸豆蛋白暴露巯基、总巯基含量下降幅度均较大，两者随消化时间延长均略有增加；扫描电子显微镜分析发现芸豆蛋白经胃部模拟消化后呈现颗粒状，且无序排列形成细密的网状结构。

Antioxidant Activity and Structural Characteristics of in Vitro Digestion Products of Purple Speckled Kidney Bean(Phaseolus vulgaris L.)Protein

This study was performed in order to explore the antioxidant activity and structural characteristics of purple speckled kidney bean protein during simulated gastric digestion in vitro.Experimental results showed that as the digestion proceeded,the degree of hydrolysis(DH)and the solubility of the protein increased significantly due to enzymatic action,and more and more peptides with low molecular masses were produced resulting in increased antioxidant activity of the digestion product.At the end of digestion,the total antioxidant capacity and ferric ion reducing power increased by 296.97%and 54.01%as compared to the protein,respectively.Fourier transform infrared(FTIR)spectroscopy analysis showed that the secondary structure of the protein changed significantly after the digestion process.The relative contents of α-helix and β-turn increased and the relative content of β-sheet decreased with increasing digestion time.The contents of free sulfhydryl group and total sulfhydryl group of kidney bean protein decreased greatly after simulated gastric digestion,although they only slightly increased with the extension of digestion time.Under scanning electron microscopy(SEM),the digested protein exhibited granules that were arranged in a disorderly manner to form a dense reticular structure.