The influence of quillaja saponin on the formation and stability of water-in-oil-in-water (W₁/O/W₂) emulsions was investigated. In particular, the ability of these emulsions to encapsulate iron (ferrous sulfate) in a form that would not promote lipid oxidation was examined. The emulsions were formed using a two-step process. First, iron sulfate was dissolved in the aqueous phase used to form 20 wt% water-in-oil (W₁/O) emulsions stabilized by polyglycerol polyricinoleate (PGPR). Second, W₁/O/W₂ emulsions were fabricated by homogenizing the W₁/O emulsions (20 wt%) with another aqueous phase (80 wt%) containing quillaja saponin (0.5, 1, 2, 3, and 4 wt%). The diameter of the oil droplets in the W₁/O/W₂ emulsions decreased with increasing saponin concentration. Confocal microscopy confirmed that the W₁/O/W₂ emulsions consisted of tiny water droplets entrapped inside oil droplets that were dispersed in an external water phase. Rheological analysis showed the W₁/O/W₂ emulsions were shear-thinning fluids. The iron encapsulation efficiency of the emulsions remained high (> 82%) throughout storage for 28 days at ambient temperature. Lipid oxidation of the iron-loaded W₁/O/W₂ emulsions could be retarded by incorporation of rice bran stearin in the oil phase. The double emulsions developed in this work have potential for encapsulation and delivery of iron in functional foods containing oxidizable lipids.

中文翻译：

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使用天然亲水性表面活性剂（皂素）配制的W 1 / O / W 2乳液中铁的包封：表面活性剂含量和油相结晶的影响

研究了奎拉加皂苷对水包油型水包水（W ₁ / O / W ₂）乳液的形成和稳定性的影响。特别地，检查了这些乳液以不促进脂质氧化的形式包封铁（硫酸亚铁）的能力。使用两步法形成乳液。首先，将硫酸铁溶解在水相中，该水相用于形成20％（重量）的油包水（W ₁ / O）乳液，该乳液通过聚甘油多蓖麻油酸酯（PGPR）稳定。其次，通过均化W ₁制备W ₁ / O / W ₂乳液/ O乳液（20 wt％）和另一个含有奎拉加皂苷（0.5、1、2、3和4 wt％）的水相（80 wt％）。W ₁ / O / W ₂乳液中油滴的直径随皂苷浓度的增加而减小。共聚焦显微镜证实，W ₁ / O / W ₂乳液由包裹在分散在外部水相中的油滴内部的微小水滴组成。流变分析表明，W ₁ / O / W ₂乳液是剪切稀化液。乳液在环境温度下存储28天的铁包封效率仍然很高（> 82％）。铁负载的W ₁ / O / W _2的脂质氧化可以通过在油相中加入米糠硬脂精来阻滞乳液。在这项工作中开发的双乳化液具有将铁包封和输送到含有可氧化脂质的功能性食品中的潜力。