Abstract This study investigated how different ways of assembling of faba bean protein isolate (FBPI) and chitosan (CH) affected the oil-in-water emulsion stability. Emulsions were prepared either by a soluble FBPI-CH complex to make EMC, or by FBPI first and then added non-interactive CH to make EMN, or by FBPI first and then added a secondary layer of CH via electrostatic attraction to make EML. A control emulsion EMFB was prepared by only FBPI. All emulsions contained 5% (w/v) oil and 0.5% (w/v) FBPI. EMC/EML/EMN contained 0.05% (w/v) CH. The emulsion stability was monitored at 37 °C for 7 days. EML not only showed better physical stability as indicated by the changes in droplet size, Turbiscan stability index, and microstructure (by confocal microscopy), but also exhibited superior oxidative stability as indicated by lipid oxidation products (less conjugated dienes and secondary oxidation products) and protein oxidation biomarkers (less tryptophan loss and carbonyls formation). This might be attributed to that CH enhanced formation of a layer-by-layer (LBL) interfacial structure, which increased the interfacial layer thickness/compactness and maintained the interfacial protein adsorption. In contrast, EMC demonstrated worse stability, albeit with thicker interfacial layer due to CH. This could be explained by the lower surface hydrophobicity and surface charge of soluble FBPI-CH complex. The free aqueous CH also impaired physical stability and promoted oxidation, as shown in EMN. In conclusion, CH improves the oxidative and physical stability of FBPI-containing emulsion when added as a LBL model.

中文翻译：

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界面层的组装影响蚕豆蛋白稳定的壳聚糖水包油乳液的物理和氧化稳定性

摘要 本研究探讨了蚕豆分离蛋白（FBPI）和壳聚糖（CH）的不同组装方式对水包油乳液稳定性的影响。乳液是通过可溶性 FBPI-CH 复合物制备 EMC，或先 FBPI 然后加入非相互作用 CH 制备 EMN，或先 FBPI 然后通过静电吸引加入第二层 CH 制备 EML。仅通过 FBPI 制备对照乳液 EMFB。所有乳液均含有 5% (w/v) 油和 0.5% (w/v) FBPI。EMC/EML/EMN 含有 0.05% (w/v) CH。乳液稳定性在 37°C 下监测 7 天。EML 不仅表现出更好的物理稳定性，如液滴尺寸、Turbiscan 稳定性指数和微观结构（通过共聚焦显微镜）的变化所示，但也表现出优异的氧化稳定性，如脂质氧化产物（较少的共轭二烯和次级氧化产物）和蛋白质氧化生物标志物（较少的色氨酸损失和羰基形成）所示。这可能归因于 CH 增强了逐层（LBL）界面结构的形成，这增加了界面层厚度/致密性并保持了界面蛋白质吸附。相比之下，EMC 表现出更差的稳定性，尽管由于 CH 具有更厚的界面层。这可以通过可溶性 FBPI-CH 复合物的较低表面疏水性和表面电荷来解释。如 EMN 所示，游离的水溶液 CH 也会损害物理稳定性并促进氧化。总之，当作为 LBL 模型添加时，CH 提高了含 FBPI 乳液的氧化和物理稳定性。