Ultrasound-assisted ionic liquids extraction of carotenoids from Xinjiang apricots and evaluation of their antioxidant potential

Xinjiang apricot isfavoured byconsumers because ofits distinctive aroma, high nutritive value, and abundant functional active substances. Carotenoids ofapricot are efficient antioxidants that can protect the human body from free radical attack. However, the extraction, quantification, and antioxidant activity ofcarotenoids from Xinjiang apricots have not been reported. Inthis work, ultrasound-assisted ionic liquid (ILs) extraction and optimisation ofcarotenoids from Xinjiang apricots and toevaluate their antioxidant potential. Based onBox–Behnken design (BBD), the best conditions were IL/ethanol (<i>R_IL/E</i>) ratio of1 : 2, solid-liquid ratio (<i>R_S/L</i>) of1 : 3, extraction time of17min and number ofextractions of3. The content ofcarotenoid extracted byultrasonic-assisted [Bmim][BF₄] ILs was 32.98±0.27μg·g^–1 that oftraditional extraction method was 25.05±0.35μg·g^–1. Moreover, ultrasonic-assisted ILs extraction technology can shorten the extraction time, simplify the extraction steps and increase the extraction amount. Meanwhile, inorder torecover and reuse ILs, ILs-ethanolic solution was frozen attemperatures lower than –80C, allowing the ILs precipitation and separation from the ethanol solution. Meantime, the antioxidant potential offive Xinjiang apricot varieties were evaluated byDPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] assays <i>invitro</i> and analysed by UV–vis spectroscopy and Raman spectroscopy. The results showed Shushanggan apricot has the highest carotenoid content and the strongest antioxidant activity. In conclusion, this research further proves the advantage of ultrasonic-assisted ILs in carotenoid extraction and the potential to obtain valuable carotenoids from the apricot industries.