Use of carnauba wax for the formulation of rosmarinic acid loaded solid lipid nanoparticles

The inclusion of antioxidants, or rich sources thereof (fruits, aromatic herbs, etc.) in foods is becoming a common procedure of the food industry. Rosmarinic acid (RA) is a phenolic compound with several biological activities, such as antioxidant, anti-inflammatory, antimutagenic, antibacterial and antiviral properties (Parnham and Kesselring, 1985) However, these compounds need protection from the interactions to which they are exposed when incorporated in food matrices. Hence, the formulation of loaded polyphenols nanoparticles can offer a way to protect such compounds from these interactions, in particular with dairy proteins. The use of lipid nanoparticles (SLN) has been extensively reported and represents an alternative carrier system to traditional colloidal carriers (Parhi and Suresh, 2010). Furthermore, SLNs combine advantages such as biocompatibility and biodegradability, physical stability, protection of incorporated compounds, controlled release and specific targeting (Parhi and Suresh, 2010). The increasing demand for functional foods with beneficial effects for human health, has opened the doors to the use of SLN in the food industry, with the incorporation of natural compounds with beneficial purposes. Thus, SLNs were prepared by a hot melt ultrasonication method using carnauba wax as lipid and Tween 80 as surfactant. The effects of lipid proportion in the lipid mixture and surfactant concentration were evaluated. Also, the stability of the nanoparticles during 28 days was tested in aqueous solution stored at 4 °C, tracking the mean particle size of the different formulations by photon correlation spectroscopy using a ZetaPALS, Zeta Potential Analyzer. Thermal analyses of the nanoparticles were also performed using DSC (Differential Scanning Calorimetry). The loading capacity and loading efficiency were calculated by measuring the concentration of RA in supernatants by HPLC. Surface properties and morphology were observed by Scanning Electron Microscopy (SEM).