In this study, the protein structural, foaming, and air–water interfacial properties in dough liquor (DL) ultracentrifugated from buckwheat sourdough with different concentrations of an alkali (1.0–2.5% of sodium bicarbonate) were investigated. Results showed that the alkali led to the cross-linking of protein disulfide bonds through the oxidation of free sulfhydryl groups in DL. The alterations in protein secondary and tertiary structures revealed that the alkali caused the proteins in DL to fold, decreased the hydrophobicity, and led to a less flexible but compact structure. The alkali accelerated the diffusion of proteins and decreased the surface tension of DL. In addition, the alkali notably improved the foam stability by up to 34.08% at 2.5% concentration, mainly by increasing the net charge, reducing the bubble size, and strengthening the viscoelasticity of interfacial protein films. Quantitative proteomic analysis showed that histones and puroindolines of wheat and 13S globulin of buckwheat were closely related to the changes in the alkali-induced foaming properties. This study sheds light on the mechanism of alkali-induced improvement in gas cell stabilization and the buckwheat sourdough steamed bread quality from the aspect of the liquid lamella.

中文翻译：

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碱诱导的荞麦酵母液的蛋白质结构、发泡和空气-水界面性质变化及定量蛋白质组分析


在这项研究中，研究了用不同浓度的碱（1.0-2.5% 的碳酸氢钠）超速离心荞麦酸面团的面团液（DL）中的蛋白质结构、起泡和空气-水界面特性。结果表明，碱通过DL中游离巯基的氧化导致蛋白质二硫键交联。蛋白质二级和三级结构的改变表明，碱导致DL中的蛋白质折叠，降低疏水性，并导致结构不太灵活但紧凑。碱加速了蛋白质的扩散并降低了DL的表面张力。此外，碱在2.5%浓度下显着提高了泡沫稳定性，提高幅度高达34.08%，主要是通过增加净电荷、减小气泡尺寸以及增强界面蛋白膜的粘弹性来实现的。定量蛋白质组分析表明，小麦的组蛋白和嘌呤吲哚啉以及荞麦的13S球蛋白与碱诱导发泡特性的变化密切相关。本研究从液层角度揭示了碱诱导气细胞稳定性改善和荞麦酸面团馒头品质改善的机制。