Impact of oil type on the location, partition and chemical stability of resveratrol in oil-in-water emulsions stabilized by whey protein isolate plus gum Arabic

Protein-based assemblies have been widely used for the encapsulation and protection of bioactive components. The location of bioactive components in a carrier with different compartments depends on their solubility and interaction with proteins. This work was to evaluate the impact of oil type on the location, partition, and chemical stability of resveratrol in O/W emulsions prepared by heat-denatured whey protein isolate (hWPI) without and with gum Arabic (GA). The emulsions produced from sunflower, origanum, and peppermint oils had similar size distributions (similar to 540-570 nm), which was slightly larger than that of the fish oil emulsion (similar to 370 nm). All the emulsions had a negative zeta-potential of between -38 mV and -45 mV. The addition of GA could improve both the surface protein percentage and surface protein concentration of the emulsions. Resveratrol was loaded in the peppermint oil phase, in the surface layer of sunflower oil, and origanum oil droplets, in the fish oil phase and its surface layer. The addition of GA increased the content of resveratrol in the surface layer of emulsified sunflower, fish, and origanum oil droplets but not in peppermint oil droplets. The partition of resveratrol in the whole emulsion was dependent on resveratrol solubility in the oil phase and surface protein percentage. After 30 days, resveratrol remained above 60% in the whole sunflower, origanum, and peppermint oil emulsions, which was higher than that in the whole fish oil emulsions. These results would be useful for expanding the use of emulsions in the encapsulation of oil-insoluble components.