Abstract To explore the effect of preheating-induced denaturation during protein production on the structure and gelling properties of soybean protein isolates (SPI), protein neutralization solutions were preheated at various temperature for various periods and then spray-dried. The pre-denaturation degree (PDD) of SPI was quantitatively characterized by the change in the AB subunit using non-reducing SDS-PAGE. The onset denaturation time was 180 s, 40 s, and 10 s at preheating temperatures of 80 °C, 90 °C and 100 °C. As PDD increased, the contents of free sulfhydryl group and the ordered secondary structure gradually decreased, accompanied by the unfolding of the tertiary structure. Gel hardness, G′ and G″ increased at high PDDs, where the heating time required for gel formation decreased. The highly pre-denatured proteins (e.g., SPI86.11%, and SPI100%) formed gel network structures without heating. SEM images showed that the partially pre-denatured gels (SPI22.28% and SPI86.11%) were denser and had more uniform gel networks than the native protein (SPI0) and the completely pre-denatured protein (SPI100%). This work will provide guidelines for the control of heating conditions during SPI production process to improve gelling properties.

中文翻译：

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蛋白质生产过程中预热诱导的变性对大豆蛋白质结构和凝胶特性的影响

摘要 为了探讨蛋白质生产过程中预热引起的变性对大豆分离蛋白（SPI）结构和胶凝特性的影响，将蛋白质中和溶液在不同温度下预热不同时间，然后喷雾干燥。SPI 的预变性程度 (PDD) 通过使用非还原 SDS-PAGE 的 AB 亚基的变化进行定量表征。起始变性时间分别为 180 s、40 s 和 10 s，预热温度分别为 80 °C、90 °C 和 100 °C。随着PDD的增加，游离巯基和有序二级结构的含量逐渐减少，伴随着三级结构的展开。凝胶硬度、G' 和 G'' 在高 PDD 下增加，凝胶形成所需的加热时间减少。高度预变性的蛋白质（例如，SPI86.11%、和 SPI100%) 在不加热的情况下形成凝胶网络结构。SEM 图像显示，部分预变性凝胶（SPI22.28% 和 SPI86.11%）比天然蛋白质（SPI0）和完全预变性蛋白质（SPI100%）更致密，凝胶网络更均匀。这项工作将为控制 SPI 生产过程中的加热条件以提高胶凝性能提供指导。