Liquid crystalline properties and extractability of monoolein–water systems by supercritical carbon dioxide

The influence of phase structure on the extraction recovery of monoolein from monoolein–water systems by supercritical carbon dioxide was investigated. Two monoolein–water mixtures at concentrations of 9 wt% water and 18 wt% water, respectively, were studied. 2H-NMR was used to monitor changes of the phase structures in supercritical conditions. The results showed that the phase structure and the water–monoolein interactions play a role on the extraction yield. The monoolein recovery was higher in the 9 wt% water sample in which Lα phase was present compared to the 18 wt% water sample in which the Lα melted to yield a L2 phase. When the phase structures were the same in both samples, the extraction recovery was determined by the solubility properties of the components of the system. The changes due to the presence of supercritical carbon dioxide were shown also to depend on the water concentration of the monoolein–water mixture besides the temperature. The 18 wt% mixture showed a L2 phase structure in all the range of the temperature investigated while the 9 wt% water mixture showed phase changes from Lα phase to L2 phase in the same temperature range.