A novel efficient method for the simultaneous recycle of amygdalin and oil from bitter apricot kernels: Ultrasonication based on natural deep eutectic solvent

Bitter apricot kernel (BAK) is a good source of amygdalin and oil. However, the current production process faces challenges including the inability to simultaneously extract amygdalin and oil, and the risk of toxicity due to amygdalin contamination in the oil. A novel, green and efficient ultrasonication-assisted extraction (UAE) method based on a natural deep eutectic solvent (NADES) composed of choline chloride-lactic acid (CC-LA) was established for simultaneous extraction of amygdalin and oil from BAK for the first time. Under optimizing conditions of a liquid-to-solid ratio of 18 mL/g, ultrasonic power of 420 W, temperature of 42 °C, and extraction time of 32 min, the highest yields of amygdalin and oil were achieved at 10.22 ± 0.04 % and 45.64 ± 0.24 %, respectively. The yield of amygdalin in UAE based on CC-LA was twice and nineteen times that of methanol (90 %, v/v) and water, respectively. Meanwhile, the yield of oil obtained by this new method was comparable to that by organic solvent extraction methods. The fatty acid composition of oil obtained by this method was consistent with that by conventional extraction methods. Scanning electron microscopy (SEM) analysis indicated that CC-LA and UAE had a synergistic effect on the destruction of BAK’s microstructure, which facilitated the recovery of amygdalin and oil. Molecular dynamics simulation results showed that amygdalin in CC-LA reached a higher solvent-accessible surface area (SASA) and formed more hydrogen bonds with longer lifetimes and greater stability. Furthermore, this new method demonstrated potential for industrial scalability.