College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.
Department of Agricultural Engineering Institute, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, AREEO, Mashhad 1696700, Iran.
Molecules. 2022 Nov 7;27(21):7652. doi: 10.3390/molecules27217652.
This study investigated the effect of lactic-acid-bacteria fermentation on the microstructure and gastrointestinal digestibility of soy proteins using a digestomics approach. Fermented soy protein isolates (FSPIs) under varied fermentation-terminal pH demonstrated a colloidal solution (FSPI-7.0/6.0) or yogurt-like curd (FSPI-5.0/4.0) state. Cryo-electron microscopy figures demonstrated the loosely stacked layer of FSPI-7.0/6.0 samples, whereas a denser gel network was observed for FSPI-5.0/4.0 samples. Molecular interactions shifted from dominant ionic bonds to hydrophobic forces and disulfide bonds. The gastric/intestinal digestion demonstrated that the curd samples afforded a significantly low particle size and high-soluble protein and peptide contents in the medium and late digestive phases. A peptidomics study showed that the FSPI-6.0 digestate at early intestinal digestion had a high peptidome abundance, whereas FSPI curd digestates (FSPI-5.0/4.0) elicited a postponed but more extensive promotion during medium and late digestion. Glycinin G2/G4 and β-conglycinin α/α' subunits were the major subunits promoted by FSPI-curds. The spatial structures of glycinin G2 and β-conglycinin α subunits demonstrated variations located in seven regions. Glycinin G2 region 6 (A349-K356) and β-conglycinin α subunit region 7 (E556-E575), which were located at the interior of the 3D structure, were the key regions contributing to discrepancies at the late stage.
本研究采用消化组学方法研究了乳酸菌发酵对大豆蛋白微观结构和胃肠道消化率的影响。在不同发酵终点 pH 值下，发酵大豆蛋白分离物（FSPIs）呈现出胶体溶液（FSPI-7.0/6.0）或酸奶状凝乳（FSPI-5.0/4.0）状态。冷冻电子显微镜图像显示 FSPI-7.0/6.0 样品的松散堆积层，而 FSPI-5.0/4.0 样品则观察到更密集的凝胶网络。分子相互作用从主要的离子键转变为疏水作用力和二硫键。胃/肠消化表明凝乳样品在中晚期消化阶段提供了显著较小的颗粒大小和较高的可溶性蛋白质和肽含量。肽组学研究表明，早期肠道消化的 FSPI-6.0 消化物具有较高的肽组丰度，而 FSPI 凝乳消化物（FSPI-5.0/4.0）在中晚期消化过程中引发了延迟但更广泛的促进作用。伴大豆球蛋白 G2/G4 和β-伴大豆球蛋白 α/α'亚基是 FSPI 凝乳促进的主要亚基。伴大豆球蛋白 G2 和β-伴大豆球蛋白 α 亚基的空间结构显示出位于七个区域的变化。伴大豆球蛋白 G2 区域 6（A349-K356）和β-伴大豆球蛋白 α 亚基区域 7（E556-E575）位于 3D 结构的内部，是导致后期差异的关键区域。
