Whey protein adsorbed to an interface forms a viscoelastic interfacial film but is displaced competitively from the interface by a small-molecule surfactant added afterward. The present study evaluated the impact of the covalent conjugation of high- or low-molecular-weight sodium alginate (HA or LA) to whey protein isolate (WPI) via the Maillard reaction on the ability of whey protein to resist surfactant-induced competitive displacement from the air–water interface. Surfactant added after the pre-adsorption of conjugate to the interface increased surface pressure. At a given surface pressure, the WPI–LA conjugate showed a significantly higher interfacial area coverage and lower interfacial film thickness compared to those of the WPI–HA conjugate or unconjugated WPI. The addition of LA to the aqueous phase had little effect on the interfacial area and thickness of pre-adsorbed WPI. These results suggest the importance of the molecular weight of the polysaccharide moiety in determining interfacial properties of whey protein–alginate conjugates.

中文翻译：

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海藻酸钠与乳清蛋白的美拉德偶联，增强了对表面活性剂诱导的空气-水界面竞争性置换的抵抗力。

吸附在界面上的乳清蛋白形成粘弹性界面膜，但随后被添加的小分子表面活性剂从界面竞争性地置换。本研究通过美拉德反应评估了高分子量或低分子量藻酸钠（HA或LA）与乳清蛋白分离物（WPI）的共价结合对乳清蛋白抵抗表面活性剂诱导的竞争性置换的能力的影响从空气-水界面。在共轭物预吸附到界面后添加表面活性剂会增加表面压力。在给定的表面压力下，与WPI-HA共轭或未共轭WPI相比，WPI-LA共轭具有更高的界面面积覆盖率和更低的界面膜厚度。向水相中添加LA对预吸附WPI的界面面积和厚度影响很小。这些结果表明，在确定乳清蛋白-藻酸盐结合物的界面特性时，多糖部分分子量的重要性。