This study aimed to develop an eco-friendly and high-efficiency method for extracting carotenoids from canistel pulps (CPs) by ultrasound-assisted natural fatty acids-based deep eutectic solvents (DESs). The DES consisting of menthol and capric acid (Men-CaA, 2:1) resulted in the highest total carotenoids content (TCC) of 614 ± 3 μg β-carotene equivalent (β-CE)/g DW. The conditions of ultrasound-assisted Men-CaA extraction were then further optimized by using response surface methodology (RSM). The maximum extraction yield of TCC (831.0 ± 0.3 μg β-CE/g DW) was achieved under the conditions of ultrasonic power of 320 W, liquid to solid ratio (L/S) of 6:1, temperature of 40℃, and ultrasound time of 18 min. In addition, ultrasound significantly intensified the extraction of carotenoids from CPs. The carotenoids compositions in CPs were also identified using UPLC-QTRAP-MS/MS for the first time. Men-CaA extract exhibited much higher content of lycopene (499 ± 1 μg/g DW) compared to the acetone and corn oil extracts. Molecular dynamic simulation confirmed that more non-covalent bonds were found between Men-CaA and lycopene. Overall, an ultrasound-assisted eco-friendly fatty acids-based eutectic solvent method was successfully developed for highly efficient extraction of carotenoids from agricultural by-products.
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