Abstract Multiple emulsions provide a facile route for particle preparation due to their ability to be used as liquid templates. Herein, biocompatible oil-in-water-in-oil (O1/W/O2) double emulsions were fabricated using a two-step procedure and applied as templates for preparation of calcium alginate hydrogels with encapsulated β-carotene. The encapsulation efficiency (EE) of β-carotene showed a positive correlation to the outer-to-inner droplet size ratio of the O1/W/O2 emulsion. The maximum EE, ∼50 wt%, could be achieved in the freshly prepared O1/W/O2 emulsion when using aqueous alginate of 2 wt% as the intermediate phase and β-carotene-loaded R-(+)-limonene of 0.1 wt% as the inner oil phase. Gelation of the alginate phase was induced by addition of a small amount of aqueous CaCl2 into the β-carotene-loaded O1/W/O2 emulsion. The resulting hydrogels in water were characterized by laser diffraction and several microscopy measurements. The hydrogels showed good spherical shape and their average size was a little larger than that of the emulsion droplet templates. This work contributed to the understanding of encapsulation in O1/W/O2 emulsion system and provided a novel methodology for encapsulation of carotenoids and other lipophilic bioactives.

中文翻译：

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以油包水包油（O/W/O）双乳液为模板的海藻酸钙水凝胶中β-胡萝卜素的包封

摘要 多重乳液可用作液体模板，为颗粒制备提供了一条简便的途径。在此，生物相容的油包水包油 (O1/W/O2) 双乳液采用两步法制备，并作为模板用于制备包封 β-胡萝卜素的海藻酸钙水凝胶。β-胡萝卜素的包封率 (EE) 与 O1/W/O2 乳液的内外液滴尺寸比呈正相关。当使用 2 wt% 的海藻酸盐水溶液作为中间相和 0.1 wt% 的负载 β-胡萝卜素的 R-(+)-柠檬烯时，在新制备的 O1/W/O2 乳液中可以实现最大 EE，约 50 wt% % 作为内油相。通过将少量 CaCl2 水溶液添加到负载 β-胡萝卜素的 O1/W/O2 乳液中来诱导藻酸盐相的凝胶化。所得水中的水凝胶通过激光衍射和多次显微镜测量进行表征。水凝胶显示出良好的球形，它们的平均尺寸略大于乳液液滴模板的尺寸。这项工作有助于理解 O1/W/O2 乳液体系中的封装，并为类胡萝卜素和其他亲脂性生物活性物质的封装提供了一种新方法。