Food volatile compounds facilitating H_II mesophase formation: Solubilization and stability

Four lipophilic food volatile molecules of different chemical characteristics, phenylacetaldehyde, 2,6-dimethyl-5-heptenal, linalool, and trans-4-decenal, were solubilized into binary mixtures of monoolein/water, facilitating the formation of reverse hexagonal (H_II) mesophases at room temperature without the need of solvents or triglycerides. Some of the flavor compounds are important building blocks of the hexagonal mesostructure, preventing phase transition with aging. The solubilization loads were relatively high: 12.6, 10.0, 12.6, and 10.0 wt % for phenylacetaldehyde, 2,6-dimethyl-5-heptenal, linalool, and trans-4-decenal, respectively. Phenylacetaldehyde formed mixtures of lamellar and cubic phases. Linalool, 2,6-dimethyl-5-heptenal, and trans-4-decenal induced structural shift from lamellar directly to H_II mesophase, remaining stable at room temperature. Lattice parameters were found to increase with water content and to decrease with temperature and/or food volatile content. trans-4-Decenal produces more stable H_II mesophase compared to linalool-loaded mesophase. At 40-60 °C, depending on the chemical structure and on the solubilization location of the food volatile compounds, the H_II mesophase transforms to isotropic micellar phase, facilitating the release of the food volatile compounds. Molecular interactions suggest the existence of two consecutive stages in the solubilization process.