Formation of solid shell nanoparticles with liquid ω-3 fatty acid core.

A major challenge for food and pharmaceutical industries is the engineering of nanostructures that can efficiently encapsulate bioactive compounds with enhanced physical and chemical stability, and high load. The influence of surfactant properties on the physical and chemical stability of (i) nanostructured lipid carriers (NLC) containing tristearin and ω-3 fish oil, (ii) tristearin solid lipid nanoparticles (SLN), and (iii) ω-3 fish oil-in-water emulsions was investigated. As surfactants we used low (LM)- and high-melting (HM) lecithins. Results indicated that the presence of fish oil reduced the crystallisation temperature, melting temperature, and melting enthalpy of tristearin. NLC stabilized with HM-lecithin inhibited the oxidation of ω-3 fatty acids ≥90% compared to those stabilized with LM-lecithin. This was attributed to the solidified surfactant layer of HM-lecithin inducing crystallisation of the shell by interfacial heterogeneous nucleation. The results showed that the saturated HM-lecithin was the key in controlling the crystallisation behaviour, and thereby enabled the formation of oxidatively and physically stable lipid nanoparticles.