Department of Food Engineering, School of Food Engineering, UNICAMP, Campinas, SP, Brazil.
Center for Technology of Cereals and Chocolates, Institute of Food Technology (ITAL), Campinas, SP, Brazil.
Colloids Surf B Biointerfaces. 2020 Jun;190:110939. doi: 10.1016/j.colsurfb.2020.110939. Epub 2020 Mar 3.
The emulsion stability depends on the physicochemical properties of the dispersed phase and their interaction with the continuous phase. Surface-active compounds (SAC) are added in emulsions to reduce the interfacial tension (IT) between these phases and keep the oil droplets stabilized. Moreover, small amounts of SAC can occupy intermolecular voids in the dried matrix, reducing the oxidation. However, the formulation must reflect a trade-off between protection and emulsion stabilization. Therefore, this work aimed to identify the minimum concentration of SAC (modified starch-MS, gelatin-GE, and whey protein isolate-WPI) ranging from 0.48 to 6 % (w/w) to form and stabilize droplets of an unsaturated triglyceride (fish oil-FO) or a volatile oil (orange essential oil-OEO). GE did not change the IT (6.7 mN/m) and stabilized the emulsions only through an increase of the viscosity (∼42 mPas for FO-emulsions and ∼97 mPas for OEO-emulsions), presenting high droplet size (∼10 μm) and low surface charge (∼1.5 mV). WPI reduced the IT to a limit value (4.5 mN/m at 1.2 % w/w for OEO and 5.3 mN/m at 2.4 % w/w for FO), whereas MS reduce constantly the IT with the increase of the concentration for both oils (∼4.2 mN/m at 6 % w/w). Both WPI and MS-emulsions presented similar droplet size (∼2.0 μm), but WPI presented higher surface charge of WPI-emulsions (-45 mV) than MS-emulsions (-30 mV). This study allowed to gain a consistent understanding of structure-property relationships on the use of SAC in emulsions.
乳液稳定性取决于分散相的物理化学性质及其与连续相的相互作用。在乳液中添加表面活性剂 (SAC) 可降低这些相之间的界面张力 (IT)，并保持油滴稳定。此外，少量的 SAC 可以占据干燥基质中的分子间空隙，从而减少氧化。然而，配方必须在保护和乳液稳定性之间取得平衡。因此，本工作旨在确定最低浓度的 SAC（改性淀粉-MS、明胶-GE 和乳清蛋白分离物-WPI）范围为 0.48 至 6%（w/w），以形成和稳定不饱和甘油三酯（鱼油-FO）或挥发性油（橙油-OEO）的液滴。GE 没有改变 IT（6.7 mN/m），仅通过增加粘度（FO 乳液约为 42 mPas，OEO 乳液约为 97 mPas）来稳定乳液，呈现出较大的液滴尺寸（约 10 µm）和较低的表面电荷（约 1.5 mV）。WPI 将 IT 降低到一个极限值（对于 OEO 为 1.2%w/w 时为 4.5 mN/m，对于 FO 为 2.4%w/w 时为 5.3 mN/m），而 MS 则随着两种油的浓度增加而不断降低 IT（对于 FO 为 6%w/w 时约为 4.2 mN/m）。WPI 和 MS 乳液的液滴尺寸相似（约 2.0 µm），但 WPI 乳液的表面电荷高于 MS 乳液（-45 mV 对-30 mV）。这项研究使我们对 SAC 在乳液中的结构-性能关系有了更一致的理解。
