Department of Food Engineering and Technology (DETA), School of Food Engineering (FEA), University of Campinas (UNICAMP), Rua Monteiro Lobato, 80, 13083-862 Campinas, SP, Brazil.
Department of Food Engineering and Technology (DETA), School of Food Engineering (FEA), University of Campinas (UNICAMP), Rua Monteiro Lobato, 80, 13083-862 Campinas, SP, Brazil; Department of Food Engineering, Faculty of Animal Science and Food Engineering, University of São Paulo, Avenida Duque de Caxias Norte, 225, 13635-900 Pirassununga, SP, Brazil; Food Research Center (FoRC), University of São Paulo, Rua do Lago, 250, Semi-industrial Building, Block C, 05508-080 São Paulo, SP, Brazil.
Food Res Int. 2022 Jun;156:111123. doi: 10.1016/j.foodres.2022.111123. Epub 2022 Mar 14.
Double W/O/W emulsions can act as fat substitutes in food matrices, although synthetic emulsifiers are commonly used due to their inherent instability and susceptibility to coalescence. In order to guarantee the stability of the W/O interface, the synthetic emulsifier polyglycerol polyricinoleate (PGPR - 4.5% w/w) was used. However, the replacement of chemically synthesized ingredients by natural alternatives has been extensively pursued in food applications. In this sense, whey protein isolate (WPI) and sodium caseinate (SC) were used to stabilize the external aqueous phase (W) of water-in-oil-in-water double emulsions (W/O/W), in addition to Tween 80 that was used as a control. The composition of the internal aqueous phase and its effects on the double emulsion were studied by the addition of sodium chloride (0.2% w/w NaCl), gallic acid (0.5% w/w GA) or a GA/NaCl mixture (0.5% / 0.2% w/w). The effect of these different hydrophilic components was evaluated from measurements of droplet size, viscosity, ζ potential, interfacial tension and kinetic stability. SC-stabilized W/O/W emulsions showed better kinetic stability than WPI- and T80-systems. These results can be attributed to the initial droplet size (SC < T80 < WPI) and viscosity of the emulsions (SC < T80 < WPI). SC is a more flexible and unfolded protein that can quickly adsorb and rearrange at the interface, favoring the formation of smaller droplets and limiting the migration of inner water droplets to the outer phase. In addition to smaller droplets, the addition of SC (8% w/w) to the external aqueous phase promoted an increase in the viscosity of bulk systems, which reduced the destabilization rates by creaming and coalescence. All W/O/W systems containing NaCl in the inner aqueous phase presented greater kinetic stability during 7 days of storage. Although the addition GA was less efficient to stabilize double emulsions compared to NaCl, this phenolic compound reduced the interfacial tension, favoring the formation of WPI- and T80-droplets with smaller diameters. However, the use of GA/NaCl blend improved the stability and functionally of W/O/W double emulsions. We concluded that the type of hydrophilic emulsifier, the properties of the inner water droplets and the viscosity of phases influenced the droplet size, viscosity and kinetic stability of double emulsions. This work provides a better understanding of how composition influences the properties of double emulsions and how it can be used to design W/O/W emulsions as fat substitutes in more complex food systems.
双重 W/O/W 乳液可以在食品基质中用作脂肪替代品，尽管由于其内在的不稳定性和易于聚结，通常使用合成乳化剂。为了保证 W/O 界面的稳定性，使用了合成乳化剂聚甘油蓖麻醇酸酯（PGPR-4.5%w/w）。然而，在食品应用中，已经广泛追求用天然替代品替代化学合成成分。在这种情况下，乳清蛋白分离物（WPI）和酪蛋白酸钠（SC）被用于稳定油包水包水双重乳液（W/O/W）的外部水相（W），此外还使用了吐温 80 作为对照。通过添加氯化钠（0.2%w/wNaCl）、没食子酸（0.5%w/wGA）或 GA/NaCl 混合物（0.5%/0.2%w/w）研究了内部水相的组成及其对双重乳液的影响。从测量粒径、粘度、ζ 电位、界面张力和动力学稳定性来评估这些不同亲水性成分的效果。SC 稳定的 W/O/W 乳液显示出比 WPI 和 T80 系统更好的动力学稳定性。这些结果可以归因于初始液滴尺寸（SC <T80<WPI）和乳液的粘度（SC <T80<WPI）。SC 是一种更灵活和展开的蛋白质，它可以快速吸附并在界面上重新排列，有利于形成较小的液滴并限制内部液滴向外部相的迁移。除了较小的液滴外，将 SC（8%w/w）添加到外部水相还促进了主体系统的粘度增加，从而降低了通过乳状液和聚结的失稳速率。在 7 天的储存期间，所有含有内水相 NaCl 的 W/O/W 系统都表现出更好的动力学稳定性。尽管与 NaCl 相比，添加 GA 对稳定双重乳液的效果较差，但这种酚类化合物降低了界面张力，有利于形成具有较小直径的 WPI 和 T80 液滴。然而，使用 GA/NaCl 混合物可以改善 W/O/W 双重乳液的稳定性和功能性。我们得出结论，亲水性乳化剂的类型、内水相的性质和各相的粘度都会影响双重乳液的粒径、粘度和动力学稳定性。这项工作提供了对组成如何影响双重乳液性质的更好理解，以及如何将其用于设计作为更复杂食品系统中脂肪替代品的 W/O/W 乳液。
