Natural pH and temperature-sensitive hydrogel-emulsion carriers for co-delivery of hydrophobic and hydrophilic bioactive ingredients in the gastrointestinal tract

The low oral bioavailability of some bioactive ingredients is a challenge in the supplement and functional food areas. Consequently, there is a need for innovative carrier technologies that can increase the solubility, stability, release, and absorption of these ingredients within the human gastrointestinal tract. Furthermore, some bioactive ingredients may exert their synergistic activities when delivered together. The objective of this study was to design natural carriers that could simultaneously deliver both hydrophobic and hydrophilic bioactive ingredients, thereby increasing their ability to exert synergistic effects. Initially, model hydrophobic (lycopene) and hydrophilic (riboflavin) ingredients were encapsulated in the oil and internal water phases of water-in-oleic acid-in-water (W/O/W) emulsions, respectively. These emulsions were then dispersed into two kinds of alginate-based matrices, which may be suitable for different applications: calcium alginate gels (solid) or EDTA-calcium alginate sols (fluid). Oleic acid was used as an oil phase in the W/O/W emulsions to provide temperature-triggered release, whereas alginate-based matrices were used to provide pH-triggered release. The carriers were stable in a simulated gastric juice but released the bioactive ingredients in a simulated small intestinal juice. The calcium alginate matrix increased the light stability of the bioactive ingredients. Encapsulation improved the bioaccessibility of the co-delivered bioactive ingredients. This study provides new strategies that can be used for designing pH- and temperature-sensitive carrier for intestinal targeted delivery of hydrophobic and hydrophilic food bioactive ingredients.