Evaluation of new natural deep eutectic solvents for the extraction of isoflavones from soy products

Natural deep eutectic solvents (NADESs) are considered to be new, safe solvents in green chemistry that can be widely used in many chemical processes such as extraction or synthesis. In this study, a simple extraction method based on NADES was used for the isolation of isoflavones (daidzin, genistin, genistein, daidzein) from soy products. Seventeen different NADES systems each including two or three components were tested. Multivariate data analysis revealed that NADES based on a 30% solution of choline chloride: citric acid (molar ratio of 1:1) are the most effective systems for the extraction of isoflavones from soy products. After extraction, the analytes were detected and quantified using ultra-high performance liquid chromatography with ultraviolet detection (UHPLC-UV). The proposed NADES extraction procedure achieved enrichment factors up to 598 for isoflavones and the recoveries of the analytes were in the range 64.7–99.2%. The developed NADES extraction procedure and UHPLC-UV determination method was successfully applied for the analysis of isoflavones in soy-containing food samples. The obtained results indicated that new natural deep eutectic solvents could be an alternative to traditional solvents for the extraction of isoflavones and can be used as sustainable and safe extraction media for another applications.