Acid precipitation has a great influence on the extraction and structural properties of plant proteins, especially for proteins in poorly soluble raw materials. The structural and functional properties of okara protein (OP) precipitated by different acids (HCl, citric acid, and malic acid) were investigated. HCl induced the lowest surface hydrophobicity (H₀), while citric acid led to the lowest absolute value of ζ-potential and the largest size of OP. By contrast, the highest H₀ and absolute value of ζ-potential, as well as the smallest size, were observed in OP precipitated by malic acid. Basic 7S globulin (Bg 7S) was detected in OP, especially for OP precipitated by malic acid and citric acid. Differences were also observed in the functional properties of OP. HCl contributed to the highest solubility, water holding capacity (WHC), foaming ability index (FAI), and foaming stability index (FSI). Citric acid induced the highest oil holding capacity (OHC) and emulsifying stability index (ESI). Malic acid resulted in the lowest FAI, FSI, and ESI. These results indicated that acid precipitation was able to alter functional properties of okara protein via affecting the structure, which made it be appliable in extracting protein from poorly soluble raw materials and widen the applications of obtained protein.

酸沉淀对植物蛋白的提取和结构特性有很大影响，特别是对于难溶性原料中的蛋白。研究了由不同酸（HCl，柠檬酸和苹果酸）沉淀的豆渣蛋白（OP）的结构和功能特性。HCl引起最低的表面疏水性（H ₀），而柠檬酸导致ζ势的绝对值最小，OP的大小最大。相反，最高H ₀在苹果酸沉淀的OP中观察到ζ电位的绝对值以及最小的尺寸。在OP中检测到碱性7S球蛋白（Bg 7S），特别是对于苹果酸和柠檬酸沉淀的OP。还观察到OP的功能性质上的差异。HCl贡献了最高的溶解度，持水量（WHC），起泡能力指数（FAI）和起泡稳定性指数（FSI）。柠檬酸具有最高的持油量（OHC）和乳化稳定性指数（ESI）。苹果酸的FAI，FSI和ESI最低。这些结果表明酸沉淀能够改变豆渣的功能特性 通过影响蛋白质的结构，使其可用于从难溶性原料中提取蛋白质，拓宽了所得蛋白质的应用范围。