SummaryIn this work, soy protein isolates (SPIs) were subjected to microparticulation, turning soy protein ingredients into microparticles with improved thermal stability which could be used in high‐protein foods. The pH is a critical determinant in microparticulation. Our work is mainly to investigate the effect of pH on the formation and properties of protein microparticles. To clarify the effects of pH conditions on the properties of the resulting particles, microparticulation was performed at different pH conditions (7.0, 6.0 and 5.0). Aggregation behaviours described by the parameters calculated from the protein dispersion viscosity combined with the observation of the morphology change were used to analyse the particle formation process. For the microparticles prepared at pH 5.0, soy proteins were more inclined to aggregate into clusters on a micro‐scale which had a flexible conformation. After spray drying, This powder could be easily dispersed in water, creating a dispersion with a protein concentration of 10 wt%. At this concentration, the thermal gelation capacity of the proteins was observed to decrease. Conversely, the tendency of protein aggregation was largely restricted when soy protein microparticulation was carried out at pH 7.0. As these soy protein particles in nano‐scale were dispersed in water, a decrease rather than an increase was recorded in the viscosity of this dispersion after it was heated, suggesting that these particles had improved thermal stability. This work has demonstrated that implementing appropriate pH conditions during microparticulation can prepare soy protein particles with different sizes and rheological properties, which might meet the demands of various food processing.

中文翻译：

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微观结构改变和功能特性提升：通过pH值控制大豆蛋白微粒的结构

摘要在这项工作中，对大豆分离蛋白（SPI）进行了微粒化，将大豆蛋白成分转化为具有改善的热稳定性的微粒，可用于高蛋白食品。 pH 值是微粒化的关键决定因素。我们的工作主要是研究pH值对蛋白质微粒形成和性质的影响。为了阐明 pH 条件对所得颗粒特性的影响，在不同的 pH 条件（7.0、6.0 和 5.0）下进行微粒化。通过蛋白质分散粘度计算的参数描述的聚集行为结合形态变化的观察来分析颗粒形成过程。对于在 pH 5.0 下制备的微粒，大豆蛋白更倾向于在微观尺度上聚集成具有灵活构象的簇。喷雾干燥后，这种粉末可以很容易地分散在水中，形成蛋白质浓度为 10 wt% 的分散体。在此浓度下，观察到蛋白质的热凝胶能力降低。相反，当在pH 7.0下进行大豆蛋白微粒化时，蛋白质聚集的倾向受到很大限制。当这些纳米级大豆蛋白颗粒分散在水中时，加热后该分散体的粘度下降而不是增加，这表明这些颗粒具有改善的热稳定性。这项工作表明，在微粒化过程中采用适当的pH条件可以制备具有不同尺寸和流变特性的大豆蛋白颗粒，这可能满足各种食品加工的需求。