Lipid based nanostructured delivery systems with core–shell architecture were designed for poorly water soluble bioactive compounds, such as curcumin, in order to control their release, especially in the mouth environment, and therefore to reduce the perception of their bitter taste.
The design was based on three different phases: (a) self- assembling of lipids, such as lecithin, monoolein and vegetable oils, to form the cores where the bioactives are incorporated, (b) particles formation by high pressure homogenization-assisted nanodispersion in water, using different emulsion stabilizers, such as Tween 20 and whey protein isolate (WPI), and (c) consolidation of the shell by addition of an outer layer of modified starch (MS).
The selection of the ingredients and their formulation was driven by release rate of the encapsulated bioactive compounds, monitored at each phase through in vitro release studies simulating mastication and gastro-intestinal digestion, with the final goal of ensuring low release during mastication but high bioaccessibility during digestion.
The in vitro release kinetics under simulated mastication showed that core formulations consisting of monoolein sunflower oil and water (ratio 1:1:1) minimized curcumin release, therefore this formulation was selected for further dispersion in water.
Among the different stabilizers tested, Tween 20 caused an initial burst release followed by slow and sustained release, which is in agreement with the observed softer and thinner shell structure (100 nm), while WPI and WPI+MS-stabilized formulations showed a slow and sustained release, which is in agreement with the thicker and more rigid structure of the shell (260 nm).
In addition, the biopolymer-based formulations also ensured high curcumin bioaccessibility under simulated gastro-intestinal digestion, and significant physic-chemical stability under accelerated aging.
In conclusion, this research showed that a delivery system platform based on core-shell nanostructured lipids, stabilized with protein and modified starch, has the potential to be exploited as a carrier for bioactive compounds, such as curcumin, to enable taste masking but high bioaccessibility.
Principal investigator: Dr. Francesco Donsì fdonsi@unisa.it
