The main purpose of this study was to investigate the effects on the molecular structure and the properties of soybean proteins isolate (SPI) after two modifications: (1) peracetic acid oxidative cleavage of its disulfide bonds and (2) the subsequent addition of covalently bonded glucose to the SPI containing the cleaved disulfide bonds. An appropriate amount of peracetic acid will be capable of enhancing the surface properties of SPI significantly; however, excessive oxidation can obtain undesirable results. When the concentration of peracetic acid was 0.4%, following by 35.5% of the disulfide bond cleavage, compared with those of natural SPI, the foaming capacity (FC), foaming stability (FS), emulsifying capacity (EC), and emulsifying stability (ES) of oxidized-SPI were increased by 82.0%, 65.8%, 58.5%, and 41.5%, respectively. The surface activity of oxidized-SPI could be promoted by glucose modification, and the FC, FS, EC, and ES of oxidized-SPI have further risen to 146.8%, 96.0%, 131.4%, and 40.3%, respectively, after the further glucose modification. Particle size measurements showed bimodality for the SPI that was modified with glucose with a portion of smaller sizes seen. Fluorescence spectroscopy and circular dichroism measurements demonstrate that extensibility increases; flexibility is enhanced; and glycosylation occurs more readily due to the oxidation of SPI. When grafted with glucose, these oxidized soybean protein products produce more ideal foaming and display better emulsification properties.

中文翻译：

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二硫键断裂和随后的葡萄糖修饰对 SPI 表面活性和结构的影响

本研究的主要目的是研究两种修饰后对大豆分离蛋白 (SPI) 分子结构和性质的影响：(1) 过乙酸氧化裂解其二硫键和 (2) 随后添加共价键葡萄糖到含有裂解的二硫键的 SPI。适量的过氧乙酸能显着提高SPI的表面性能；然而，过度氧化会导致不良结果。当过氧乙酸浓度为0.4%，二硫键断裂35.5%时，与天然SPI相比，起泡能力（FC）、起泡稳定性（FS）、乳化能力（EC）和乳化稳定性（ ES) 的氧化-SPI 分别增加了 82.0%、65.8%、58.5% 和 41.5%。氧化-SPI的表面活性可以通过葡萄糖修饰来提高，氧化-SPI的FC、FS、EC和ES分别进一步上升到146.8%、96.0%、131.4%和40.3%。葡萄糖修饰。粒度测量显示 SPI 的双峰性，该 SPI 用葡萄糖修饰，可见部分较小尺寸。荧光光谱和圆二色性测量表明可扩展性增加；灵活性增强；由于 SPI 的氧化，糖基化更容易发生。当用葡萄糖接枝时，这些氧化大豆蛋白产品会产生更理想的发泡和更好的乳化性能。分别在进一步的葡萄糖修饰后。粒度测量显示 SPI 的双峰性，该 SPI 用葡萄糖修饰，可见部分较小尺寸。荧光光谱和圆二色性测量表明可扩展性增加；灵活性增强；由于 SPI 的氧化，糖基化更容易发生。当用葡萄糖接枝时，这些氧化大豆蛋白产品会产生更理想的发泡和更好的乳化性能。分别在进一步的葡萄糖修饰后。粒度测量显示 SPI 的双峰性，该 SPI 用葡萄糖修饰，可见部分较小尺寸。荧光光谱和圆二色性测量表明可扩展性增加；灵活性增强；由于 SPI 的氧化，糖基化更容易发生。当用葡萄糖接枝时，这些氧化大豆蛋白产品会产生更理想的发泡和更好的乳化性能。由于 SPI 的氧化，糖基化更容易发生。当用葡萄糖接枝时，这些氧化大豆蛋白产品会产生更理想的发泡和更好的乳化性能。由于 SPI 的氧化，糖基化更容易发生。当用葡萄糖接枝时，这些氧化大豆蛋白产品会产生更理想的发泡和更好的乳化性能。