Nutraceutical nanoemulsions: influence of carrier oil composition (digestible versus indigestible oil) on β-carotene bioavailability.

Carotenoids, such as β-carotene, are widely used in foods and beverages as natural colorants and nutraceuticals. We investigated the influence of carrier oil composition (ratio of digestible to indigestible oil) on the physical stability, microstructure and bioaccessibility of β-carotene nanoemulsions using a simulated gastrointestinal tract model. β-Carotene nanoemulsions (d < 150 nm) were formed by high-pressure homogenization using sucrose monoester and lysolecithin as emulsifiers, and mixtures of corn oil (digestible) and lemon oil (indigestible) as the lipid phase. All of the nanoemulsions underwent extensive droplet aggregation under mouth, stomach and small intestine conditions. The extent of free fatty acid production in the small intestine increased as the amount of digestible oil in the droplets increased. The bioaccessibility of β-carotene also increased with increasing digestible oil content, ranging from ∼5% for the pure lemon oil system to ∼76% for the pure corn oil system. This effect was attributed to the ability of mixed micelles formed from triglyceride digestion products (free fatty acids and monoglycerides) to solubilize β-carotene. This study provides important information for developing effective delivery systems for lipophilic bioactive components in food and beverage applications.