An eco-friendly approach to enhance the extraction and recovery efficiency of isoflavones from kudzu roots and soy molasses wastes using ultrasound-assisted extraction with natural deep eutectic solvents (NADES)

The extraction efficiency, recovery, quantification, and stability of isoflavones (daidzein, genistein and puerarin) from the wastes /by-products of kudzu roots and soy molasses were evaluated by using natural deep eutectic solvents (NADESs) coupled with ultrasound-assisted extraction. The NADES extraction was compared with the conventional Soxhlet extraction technique, and the extracted isoflavones were quantified using HPLC-UV/Vis. Results showed extractability of puerarin to be significantly increased (p < 0.0001) in proportion to the increased water concentration of NADES (9.7 ± 0.2, 12.6 ± 0.2, and 14.8 ± 0.3 mg/g in NADESs containing 10%, 20%, and 30% water, respectively). Despite having less isoflavone content, kudzu roots and soy molasses extracts obtained using NADES exhibited higher antioxidant activity when compared with methanolic extracts. Further, NADES extracts also markedly reduced the degradation degree of isoflavones. The results of this investigation support the use of green extraction techniques to obtain value-added components like isoflavones from wastes/by-products like that of kudzu roots and soy molasses, which are envisaged to find future potential applications in the food and pharmaceutical industries.