Protein/polysaccharide complexes can be formed by electrostatic interactions and may be useful for enhancing the stability of nanoemulsions containing short-chain alkanes, which are highly prone to destabilization by Ostwald ripening. The study aimed to assess the capacity of biopolymer complexes composed of whey protein isolate (WPI) and sugar beet pectin (SBP) to form and stabilize interfacially structured nanoemulsions. Nanoemulsions were stored for 21 days at room temperature to assess their stability against Ostwald ripening over time. Complexes showed higher emulsifying capacity than biopolymers alone since particle size of complex-stabilized nanoemulsions remained stable (d_4;3~0.26 μm) for at least 48 h after preparation, whereas WPI- or SBP-stabilized nanoemulsions were prone to destabilization during the first 24 h reaching values around 1 μm. Moreover, while the final particle size observed for the latter during the 21 days of storage was around 8 μm, complex-stabilized nanoemulsions exhibited particle sizes up to 2.34 μm, which had a direct impact in delaying creaming. Moreover, complex-stabilized nanoemulsions exhibited negative ζ-potential with similar values to those stabilized by SBP (−20.4 and − 22.1 mV, respectively) while the interfacial rheology behavior of complex-stabilized systems was more similar to those stabilized by WPI. This evidences that the protein fraction may be adsorbed at the oil interface thus dominating the interface rheology, whereas pectin chains located on the periphery of the complex and oriented towards the water phase may confer negative interfacial charge to oil droplets. These results indicated that WPI/SBP complexes were more effective than the biopolymers alone in preventing Ostwald ripening in decane-in-water nanoemulsions.

中文翻译：

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蛋白质/多糖复合物可稳定癸烷水纳米乳剂

蛋白质/多糖复合物可以通过静电相互作用形成，并且可用于增强包含短链烷烃的纳米乳剂的稳定性，而纳米乳剂很容易因奥斯特瓦尔德熟化而不稳定。该研究旨在评估由乳清蛋白分离物（WPI）和甜菜果胶（SBP）组成的生物聚合物复合物形成和稳定界面结构纳米乳液的能力。纳米乳剂在室温下储存21天，以评估其抗奥斯特瓦尔德熟化的稳定性。与复合物相比，复合物具有更高的乳化能力，因为复合物稳定的纳米乳剂的粒径保持稳定（d _{4; 3}在制备后至少48小时内（〜0.26μm），而WPI或SBP稳定的纳米乳剂在最初的24 h内倾向于不稳定，达到约1μm的值。此外，尽管在储存的21天中观察到的最终粒径为8微米左右，但复合物稳定的纳米乳剂的粒径最高达2.34微米，这直接影响了延迟乳化。此外，复合物稳定的纳米乳液表现出负的ζ电位，其值与SBP稳定的负电位相似（分别为-20.4和-22.1 mV），而复合物稳定的系统的界面流变行为与WPI稳定的界面流变行为更相似。这证明蛋白质部分可能被吸附在油界面上，从而主导了界面流变学，而位于复合物外围且朝向水相的果胶链可能会给油滴带来负界面电荷。这些结果表明，WPI / SBP复合物在防止癸烷水纳米乳液中的奥斯特瓦尔德熟化方面比单独的生物聚合物更有效。