Dai Lei, Sun Cuixia, Wang Di, Gao Yanxiang
Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Laboratory for Food Quality and Safety, Beijing Key Laboratory of Functional Food from Plant Resources, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing, P. R. China.
PLoS One. 2016 Nov 28;11(11):e0167172. doi: 10.1371/journal.pone.0167172. eCollection 2016.
Lecithin, a naturally small molecular surfactant, which is widely used in the food industry, can delay aging, enhance memory, prevent and treat diabetes. The interaction between zein and soy lecithin with different mass ratios (20:1, 10:1, 5:1, 3:1, 2:1, 1:1 and 1:2) in ethanol-water solution and characterisation of zein and lecithin composite colloidal nanoparticles prepared by antisolvent co-precipitation method were investigated. The mean size of zein-lecithin composite colloidal nanoparticles was firstly increased with the rise of lecithin concentration and then siginificantly decreased. The nanoparticles at the zein to lecithin mass ratio of 5:1 had the largest particle size (263 nm), indicating that zein and lecithin formed composite colloidal nanoparticles, which might aggregate due to the enhanced interaction at a higher proportion of lecithin. Continuing to increase lecithin concentration, the zein-lecithin nanoparticles possibly formed a reverse micelle-like or a vesicle-like structure with zein in the core, which prevented the formation of nanoparticle aggregates and decreased the size of composite nanoparticles. The presence of lecithin significantly reduced the ζ-potential of zein-lecithin composite colloidal nanoparticles. The interaction between zein and lecithin enhanced the intensity of the fluorescence emission of zein in ethanol-water solution. The secondary structure of zein was also changed by the addition of lecithin. Differential scanning calorimetry thermograms revealed that the thermal stability of zein-lecithin nanoparticles was enhanced with the rise of lecithin level. The composite nanoparticles were relatively stable to elevated ionic strengths. Possible interaction mechanism between zein and lecithin was proposed. These findings would help further understand the theory of the interaction between the alcohol soluble protein and the natural small molecular surfactant. The composite colloidal nanoparticles formed in this study can broaden the application of zein and be suitable for incorporating water-insoluble bioactive components in functional food and beverage products.
卵磷脂是一种天然的小分子表面活性剂，广泛应用于食品工业，具有延缓衰老、增强记忆、预防和治疗糖尿病的作用。研究了乙醇 - 水溶液中不同质量比（20:1、10:1、5:1、3:1、2:1、1:1和1:2）的玉米醇溶蛋白与大豆卵磷脂之间的相互作用，以及通过反溶剂共沉淀法制备的玉米醇溶蛋白与卵磷脂复合胶体纳米颗粒的表征。玉米醇溶蛋白 - 卵磷脂复合胶体纳米颗粒的平均尺寸首先随着卵磷脂浓度的升高而增大，然后显著减小。玉米醇溶蛋白与卵磷脂质量比为5:1时的纳米颗粒粒径最大（263 nm），这表明玉米醇溶蛋白和卵磷脂形成了复合胶体纳米颗粒，在卵磷脂比例较高时，由于相互作用增强，可能会发生聚集。继续增加卵磷脂浓度，玉米醇溶蛋白 - 卵磷脂纳米颗粒可能形成以玉米醇溶蛋白为核心的反胶束状或囊泡状结构，这阻止了纳米颗粒聚集体的形成并减小了复合纳米颗粒的尺寸。卵磷脂的存在显著降低了玉米醇溶蛋白 - 卵磷脂复合胶体纳米颗粒的ζ电位。玉米醇溶蛋白与卵磷脂之间的相互作用增强了乙醇 - 水溶液中玉米醇溶蛋白的荧光发射强度。添加卵磷脂也改变了玉米醇溶蛋白的二级结构。差示扫描量热法热谱图显示，随着卵磷脂含量的增加，玉米醇溶蛋白 - 卵磷脂纳米颗粒的热稳定性增强。复合纳米颗粒对升高的离子强度相对稳定。提出了玉米醇溶蛋白与卵磷脂之间可能的相互作用机制。这些发现将有助于进一步理解醇溶性蛋白质与天然小分子表面活性剂之间相互作用的理论。本研究中形成的复合胶体纳米颗粒可以拓宽玉米醇溶蛋白的应用范围，并适用于在功能性食品和饮料产品中加入水不溶性生物活性成分。
