Application of natural deep eutectic solvents for the greenextraction of vanillin from vanilla pods

In recent years, a new type of solvents, natural deep eutectic solvents (NADES), have been developed and are gaining popularity as an alternative green solvent to conventional organic solvents. The traditional extraction of flavor or fragrance from plant materials such as vanillin is a tedious procedure that involves the use of organic solvents. In this case the solubility of vanillin and its extractability from vanilla pods in 14 NADES was evaluated. The solubility in some NADES such as lactic acid: propanediol (620mg/mL) and lactic acid: fructose (320mg/mL) was found to be almost similar to that of organic solvents e.g. methanol (632.94mg/mL) or ethanol (375.81mg/mL). Interestingly, the extractability of vanillin from vanilla pods did not reflect the results observed for the solubility tests. Some NADES with constituents that are suitable as food ingredients such as citric acid-fructose-glucose (CAFG), fructose-glucose (FG), malic acid-glucose (MAG), and malic acid-fructose-glucose (MAFG), showed a higher extraction power (7.6, 10.1, 16.7, and 16.3mg/g DW, respectively) than ethanol (4.4mg/g DW). The discrepancy between solubility and extractability might be due to differences in the interaction with the matrix depending on the NADES. The effect of water content in some NADES on the extractability of vanillin was also studied. With the high extraction capacity and the absence of toxicity of their components, NADES are very suitable for extraction of flavours and fragrances used in food and cosmetics.