Abstract The functional performance of food proteins can sometimes be enhanced by forming conjugates or complexes with other food-grade molecules. In this study, the impact of fabrication conditions (pH and mixing ratio) on the formation and properties of phytic acid (PA)-whey protein isolate (WPI) complexes was evaluated. In addition, the ability of the complexes to form and stabilize oil-in-water emulsions was characterized. Emulsions were formed using a high-shear mixer to simulate the production of commercial foods such as dressings and sauces. Most emulsions were highly unstable to creaming due to the relatively large size of the oil droplets they contained (d > 30 μm). Under acidic conditions, emulsions stabilized by PA-WPI complexes were more resistant to creaming and formed thicker cream layers than those stabilized by WPI alone, which was attributed to electrostatic bridging of the cationic protein-coated oil droplets by anionic phytic acid. Evidence for increased droplet-droplet attraction was confirmed by bulk rheology measurements: emulsions stabilized by PA-WPI complexes had a much higher viscosity than those stabilized by WPI. Interfacial tension measurements showed that the PA-WPI complexes adsorbed to an oil-water interface more rapidly than either PA or WPI molecules, as well as producing a greater reduction in interfacial tension. Surface rheology measurements indicated that the dilatational elastic modulus of the interfaces formed by the PA-WPI complexes was less than that formed by WPI alone, indicating that the PA inhibited interfacial protein cross-linking. Our results, indicate that even relatively low PA-to-WPI ratios (1:20) can be used to modulate the physicochemical properties and long-term stability of protein-coated oil droplets, thereby providing an effective strategy for designing food emulsions with improved functionality.

中文翻译：

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乳清蛋白与植酸络合对其乳化和稳定特性的影响

摘要 有时可以通过与其他食品级分子形成结合物或复合物来增强食品蛋白质的功能性能。在这项研究中，评估了制造条件（pH 值和混合比）对植酸 (PA)-乳清蛋白分离物 (WPI) 复合物的形成和性质的影响。此外，还表征了复合物形成和稳定水包油乳液的能力。乳液是使用高剪切混合器形成的，以模拟商业食品（如调味品和酱汁）的生产。由于它们所含的油滴尺寸相对较大（d > 30 μm），大多数乳液对乳脂化非常不稳定。在酸性条件下，由 PA-WPI 复合物稳定的乳液比单独使用 WPI 稳定的乳液更耐乳霜化并形成更厚的奶油层，这归因于阴离子植酸对阳离子蛋白质包被的油滴的静电桥接。体积流变学测量证实了液滴-液滴吸引力增加的证据：由 PA-WPI 复合物稳定的乳液比由 WPI 稳定的乳液具有更高的粘度。界面张力测量表明，PA-WPI 复合物比 PA 或 WPI 分子更快地吸附到油-水界面，并且界面张力的降低幅度更大。表面流变学测量表明，PA-WPI 复合物形成的界面的膨胀弹性模量小于单独的 WPI，表明 PA 抑制了界面蛋白质交联。我们的结果表明，即使 PA 与 WPI 的比率相对较低 (1: