Department of Food Science, University of Massachusetts, Amherst, MA 01003, USA.
Department of Food Science, University of Massachusetts, Amherst, MA 01003, USA.
Food Res Int. 2021 Feb;140:109864. doi: 10.1016/j.foodres.2020.109864. Epub 2020 Nov 4.
Electrically charged food-grade biopolymers can be used to form multilayer coatings around the lipid droplets in oil-in-water emulsions using a sequential layer-by-layer electrostatic deposition approach. In principle, this approach can be used to improve the stability and enhance the functionality of food emulsions. In this study, multilayer coatings were formed from saponins, polypeptides, and polysaccharides using medium chain triglyceride (MCT) lipid droplets as templates (pH 4.0). First, an emulsion containing negatively charged lipid droplets was created using quillaja saponin (QS) as an anionic emulsifier. Second, these anionic droplets were coated with a cationic polypeptide (poly-L-lysine, PLL) to form positively-charged droplets. Finally, these cationic droplets were coated with a negatively-charged polysaccharide, either pectin (PE) or κ-carrageenan (KC), to form anionic droplets. Overall, the 1-layer emulsions had the best resistance to salt, pH, and heat, indicating that quillaja saponins were effective emulsifiers. The 2-layer emulsions had better pH-stability than the 3-layer emulsions, which tended to strongly aggregate under acidic conditions. Conversely, the 3-layer emulsions had better salt-stability than the 2-layer emulsions, which tended to aggregate strongly even at low salt levels (50-100 mM NaCl). All the emulsions were relatively stable to heating (90 °C, 30 min). Overall, our results provide useful insights into the formulation of stable multilayer emulsions from food-grade emulsifiers and biopolymers. There appears to be little advantage to using the multilayer technology to enhance the physical stability of saponin-coated lipid droplets, but there may be advantages in terms of extending their functional properties, which will be explored in future studies.
带电荷的可食用生物聚合物可以使用顺序逐层静电沉积方法，在水包油乳液中的脂质滴周围形成多层涂层。原则上，这种方法可以用于提高食品乳液的稳定性和增强其功能性。在这项研究中，使用中链甘油三酯 (MCT) 脂质滴作为模板 (pH 值 4.0)，由皂素、多肽和多糖形成多层涂层。首先，使用荜澄茄皂苷 (QS) 作为阴离子乳化剂制备带负电荷的脂质滴乳液。其次，用阳离子多肽 (聚-L-赖氨酸，PLL) 涂覆这些阴离子滴，形成带正电荷的滴。最后，用带负电荷的多糖，果胶 (PE) 或κ-卡拉胶 (KC)，涂覆这些阳离子滴，形成阴离子滴。总体而言，1 层乳液具有最好的盐、pH 值和热稳定性，表明荜澄茄皂苷是有效的乳化剂。2 层乳液的 pH 值稳定性优于 3 层乳液，3 层乳液在酸性条件下容易强烈聚集。相反，3 层乳液的盐稳定性优于 2 层乳液，即使在低盐水平 (50-100 mM NaCl) 下也容易强烈聚集。所有乳液在 90°C 加热 30 分钟时相对稳定。总体而言，我们的研究结果为使用食品级乳化剂和生物聚合物制备稳定的多层乳液提供了有用的见解。使用多层技术来增强皂苷涂层脂质滴的物理稳定性似乎没有太大优势，但在扩展其功能特性方面可能具有优势，这将在未来的研究中进行探讨。
