Nanoemulsion delivery systems: Influence of carrier oil on β-carotene bioaccessibility

Consumption of carotenoids may reduce the incidences of certain chronic diseases, but their use in foods is currently limited because of their poor water-solubility, low bioavailability and chemical instability. We examined the impact of carrier oil type on the bioaccessibility of beta-carotene encapsulated within nanoemulsion-based delivery systems. Oil-in-water nanoemulsions (d < 200 nm) were formed using a non-ionic surfactant (Tween 20) as emulsifier and long chain triglycerides (LCT), medium chain triglycerides (MCT) or orange oil as carrier oils. The influence of carrier oil type on beta-carotene bioaccessibility was established using an in vitro model to simulate the oral, gastric and small intestinal phases of the gastrointestinal tract. The rate and extent of free fatty acid production in the intestine decreased in the order LCT approximate to MCT >> orange oil; whereas beta-carotene bioaccessibility decreased in the order LCT >> MCT > orange oil. The bioaccessibility of beta-carotene was negligible (approximate to 0%) in orange oil nanoemulsions because no mixed micelles were formed to solubilise beta-carotene, and was relatively low (approximate to 2%) in MCT nanoemulsions because the mixed micelles formed were too small to solubilise beta-carotene. In contrast, beta-carotene bioaccessibility was relatively high (approximate to 66%) in LCT nanoemulsions. Our results have important implications for the design of effective delivery systems for encapsulation of carotenoids and other lipophilic bioactive components. (C) 2012 Elsevier Ltd. All rights reserved.