Hydrophobic natural deep eutectic solvents for the sustainable extraction of carotenoids from persimmon peels

A sustainable strategy enabling the extraction of bioactive lipidic compounds, including carotenoids, from persimmon (Diospyros kaki Thunb) peel was developed in this work. Ultrasound-assisted extraction (UAE) was combined with hydrophobic natural deep eutectic solvents (NaDES). A screening of seven selected NaDES was carried out and an experimental design was employed to optimize the most favorable extraction conditions. The best conditions consisted of the use of thymol:menthol with a 2:1 molar ratio, a 33 % ultrasound amplitude, and 13.8 min extraction time. Comparison with organic solvents confirmed that NaDES allowed extractions with comparable carotenoid content but higher antioxidant capacity. The tentative identification and quantification of carotenoids present in the extracts were performed using ultra-high-performance liquid chromatography coupled with a diode-array detector. Carotenoids were successfully encapsulated with cyclodextrins, as confirmed by scanning electron microscopy and Fourier transform infrared spectroscopy-attenuated total reflection. The encapsulated extracts demonstrated high carotenoid content per 100 g of beta-cyclodextrin and percentage of encapsulated extract, antioxidant capacity, and low cytotoxicity.