Food-grade bicontinuous microemulsions

Microemulsions stabilized by sucrose esters in combination with lecithin are interesting flavour delivery systems because they allow the solubilization of very high levels of oil into an aqueous phase with relatively small amounts of surfactants. The aim of this study was to investigate microemulsions stabilized by these surfactants in order to determine the microemulsion type and the solubilizing capacity of the structures. Based on these results a good control and easy handling of the delivery systems is feasible. Pulsed Field Gradient (PFG) diffusion nuclear magnetic resonance spectroscopy revealed that at some specific ratios between both surfactants the formation of bicontinuous microemulsions takes place. In such systems, between 20% and 60% of the oil phase can be solubilized. The solubilization of lecithin in the flavour oil and the insertion of this mixture into a system containing direct micelles of sucrose ester changes the curvature of structures and allows the continuous transition from direct oil/water to bicontinuous structures to inverse water/oil microemulsions. In such inverse microemulsions up to 80% of flavour oil can be solubilized. Our investigation demonstrates that the presence of lecithin leads to an increase of the flavour oil loading, decreasing significantly the total surfactant concentration. Therefore, lecithin can be used as a tuning parameter to control the different types of microemulsions without additional hydrotropes and they can be easily adapted to different industrial applications. Copyright (c) 2013 John Wiley & Sons, Ltd.