Solid lipid nanoparticles as delivery systems for bioactive food components

The inclusion of bioactive compounds, such as carotenoids, omega-3 fatty acids, or phytosterols, is an essential requisite for the production of functional foods designed to improve the long-term health and well-being of consumers worldwide. To incorporate these functional components successfully in a food system, structurally sophisticated encapsulation matrices have to be engineered, which provide maximal physical stability, protect ingredients against chemical degradation, and allow for precise control over the release of encapsulated components during mastication and digestion to maximize adsorption. A novel encapsulation system initially developed in the pharmaceutical industries to deliver lipophilic bioactive compounds is solid lipid nanoparticles (SLN). SLN consist of crystallized nanoemulsions with the dispersed phase being composed of a solid carrier lipid-bioactive ingredient mixture. Contrary to larger colloidal solid lipid particles, specific crystal structures can be "dialed-in" in SLN by using specific surfactant mixtures and ensuring that mean particle sizes are below 100-200 nm. Moreover, in SLN, microphase separations of the bioactive compound from the solidifying lipid matrix can be prevented resulting in an even dispersion of the encapsulated compound in the solid matrix thereby improving chemical and physical stability of the bioactive. In this review article, we will briefly introduce the structure, properties, stability, and manufacturing of solid lipid particles and discuss their emerging use in food science.