School of Food Science and Engineering , South China University of Technology , Guangzhou 510640 , China.
Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety , South China University of Technology , Guangzhou 510640 , China.
J Agric Food Chem. 2018 May 2;66(17):4449-4457. doi: 10.1021/acs.jafc.8b00225. Epub 2018 Apr 20.
The natural quinoa protein isolate (QPI) was largely reflected in the nanoparticle form at pH 7.0 (∼401 nm), and the ultrasound at 20 min progressively improved the contact angle (wettability) and surface hydrophobicity of the nanoparticles. Ultrasound process also modified the type of intraparticle interaction, and the internal forces of sonicated particles were largely maintained by both disulfide bonds and hydrophobic interaction forces. In emulsion system, the ultrasound progressively increased the emulsification efficiency of the QPI nanoparticles, particularly at high protein concentration ( c > 1%, w/ v) and higher emulsion stability against coalescence. As compared with the natural QPI-stabilized emulsions, the 20 min sonicated emulsions exhibited higher packing and adsorption at the protein interface. The microstructure of emulsions that occurs is bridging flocculation of droplets at low c (≤1%, w/ v), while the amount of protein particles could be high enough to cover the droplet surface at high c ( >1%, w/ v) with hexagonal array model arrangement. Thus these results illustrated that both natural and sonicated QPI nanoparticles could be performed as effective food-grade stabilizer for Pickering emulsion; however, the sonicated QPI nanoparticles exhibited much better emulsifying and interfacial properties.
天然藜麦蛋白分离物（QPI）在 pH 7.0（约 401nm）时主要以纳米颗粒形式存在，超声 20min 可逐步改善纳米颗粒的接触角（润湿性）和表面疏水性。超声处理还改变了颗粒内相互作用的类型，超声处理后的颗粒内部力主要由二硫键和疏水相互作用力维持。在乳液体系中，超声可逐步提高 QPI 纳米颗粒的乳化效率，尤其是在高蛋白质浓度（c＞1%，w/v）和更高的乳液稳定性下，抗聚结能力更强。与天然 QPI 稳定的乳液相比，经 20min 超声处理的乳液在蛋白质界面处具有更高的堆积和吸附。发生的乳液微观结构是在低 c（≤1%，w/v）下的液滴桥接絮凝，而在高 c（＞1%，w/v）时，蛋白质颗粒的数量足以覆盖液滴表面，形成六方排列模型。因此，这些结果表明，天然和超声处理的 QPI 纳米颗粒均可作为有效的食品级 Pickering 乳液稳定剂；然而，超声处理的 QPI 纳米颗粒表现出更好的乳化和界面性能。
