The mechanical stability of protein-stabilized emulsions depends on physiochemical interactions within the interfacial protein film. However, intermolecular interactions vary with the protein's conformational state and charge and may in turn affect the mechanical stability through modifications in the three-staged interfacial stabilization; migration, adsorption and film formation at the oil/water-interface. Therefore, the aim of our study was to investigate the different protein conformations within the interfacial stabilization process by applying bulk water conditions and to determine the protein film stability against mechanical stress. For this purpose, we analyzed the structure and interactions of β-lactoglobulin in water and at the oil/water-interface at pH 7, pH 7_NaCl (containing 100 mM NaCl) and pH 9 with membrane-osmometry, Fourier-transform-infrared-spectroscopy, extrinsic fluorescence and ζ-potential. Moreover, we characterized the conformational state and charge in context with the molecule density and interfacial film properties via Langmuir trough analysis, interfacial shear and dilatational rheology. Distinct unfolding of monomers and dimers at pH 9 resulted in the lowest interfacial molecule density but at the same time the highest film stability due to pronounced structural flexibility. In comparison, β-lactoglobulin at pH 7 was monomeric, unfolding was less pronounced, and interfacial molecule density was higher. Electrostatic shielding of β-lactoglobulin dimers at pH 7_NaCl resulted in the highest density but least stable protein film that approached low molecular weight surfactant behavior due to few and weak intermolecular interactions. Our research contributes to the control of the emulsion stability against mechanical stress by varying intermolecular interactions within the interfacial protein film.

蛋白质稳定乳剂的机械稳定性取决于界面蛋白质膜内的物理化学相互作用。然而，分子间的相互作用随蛋白质的构象状态和电荷而变化，并可能反过来通过三阶段界面稳定化的修饰影响机械稳定性。油/水界面的迁移，吸附和膜形成。因此，我们的研究目的是通过应用大量水条件来研究界面稳定过程中不同的蛋白质构象，并确定针对机械应力的蛋白质膜稳定性。为此，我们分析了水和油/水界面在pH 7，pH 7 _NaCl时β-乳球蛋白的结构和相互作用。（含100 mM NaCl）和pH 9的膜渗透压测定，傅立叶变换红外光谱法，外在荧光和ζ电位。此外，我们通过朗缪尔波谷分析，界面剪切和膨胀流变学，在分子密度和界面膜特性的背景下表征了构象状态和电荷。pH值为9时，单体和二聚体的不同解折叠导致最低的界面分子密度，但同时由于具有明显的结构柔韧性，因此具有最高的膜稳定性。相比之下，pH 7的β-乳球蛋白是单体的，展开不太明显，并且界面分子密度较高。pH 7 _NaCl时β-乳球蛋白二聚体的静电屏蔽由于分子间的相互作用很少且较弱，导致了高密度但最不稳定的蛋白膜接近低分子量表面活性剂的行为。我们的研究有助于通过改变界面蛋白膜内的分子间相互作用来控制乳液对机械应力的稳定性。