Food-grade nanoemulsion filled hydrogels formed by spontaneous emulsification and gelation: Optical properties, rheology, and stability

Nanoemulsions may be used as delivery systems for lipophilic bioactive components in foods and beverages, such as oil-soluble vitamins, nutraceuticals, flavors, and antimicrobials. In this study, we examined the possibility of incorporating nanoemulsions into clear gelatin hydrogels to form optically translucent hydrogels. The effect of preparation and storage conditions on the formation and stability of nanoemulsion-filled gelatin hydrogels was studied. Nanoemulsions were produced using the spontaneous emulsification (SE) method, which simply involves addition of an organic phase (oil + surfactant) to an aqueous phase. Droplet size decreased and optical clarity increased when the SE method was performed at an elevated temperature (60 degrees C) rather than at ambient temperature (20 degrees C). Translucent filled hydrogels could be formed by incorporating the nanoemulsions into gelatin gels. The optical and rheological properties of a model gelatin gel and a commercial gelatin dessert did not change appreciably after the nanoemulsion droplets (1%) were incorporated. This approach may therefore be useful for the incorporation of various types of lipophilic bioactive agents into functional food gels. (C) 2015 Elsevier Ltd. All rights reserved.