Phase behavior of the system lecithin–water: The effects of addition of the hydrocarbon 1,8-cineole and supercritical carbon dioxide

The phase behavior of lecithin and water mixtures with addition of the hydrocarbon 1,8-cineole (C10H18O) was investigated using light microscopy and 2H NMR at atmospheric pressure and with a surplus of supercritical carbon dioxide (15 MPa) between 35 and 80 °C. The lecithin–water (LW) mixtures consisted of 10 and 20 wt.% water in lecithin to which 5, 10, and 20 wt.% cineole and supercritical carbon dioxide were added. The addition of cineole to the 10 wt.% water in lecithin samples has affected the original lamellar liquid crystalline phase present and mainly transformed it into the reversed hexagonal phase at cineole concentration of 10 wt.% and higher. This phase however only occurred when 20 wt.% cineole were added to the lecithin samples with 20 wt.% water which otherwise was lamellar. The addition of supercritical carbon dioxide to the lecithin/water samples in the absence of cineole resulted in a liquid crystalline lamellar (LC-Lα) phase and was the same as in the original phase structure at atmospheric pressure. In the lecithin/water samples with cineole, the addition of supercritical carbon had little effect on the structure.