Using novel hydrophobic deep eutectic solvents to improve a sustainable carotenoid extraction from orange peels

Carotenoids are a group of pigments that play a significant role in human health due to their antioxidant properties. This emphasises the importance of their extraction using sustainable solvents as alternatives to hazardous solvents. This study aimed to select and optimise the most promising deep eutectic solvent (DES) for a sustainable carotenoid extraction from orange peels by considering parameters such as efficiency, stability, and physicochemical properties. COSMOtherm software was used to screen 68 hydrophobic and hydrophilic DES. The experimental results demonstrated efficient extraction yields when using hydrophobic DES such as Menthol: Camphor (163.5 ± 1.1 mg/100gfw), and the stability of carotenoids in this solvent was 56% for total carotenoids after 60 days at 4 °C. The ultrasound extraction technique was selected for the optimisation process, and the optimal conditions were 60% ultrasound intensity (120 W), a solvent-to-solid ratio of 20 mL, and an extraction time of 20 min with a yield of 653.5 mg/100 gfw. The results presented in this study demonstrate the capacity of novel hydrophobic DES to extract carotenoids and identify this solvent as a good and sustainable alternative to organic solvents. Improved carotenoid extraction combined with non-toxicity, edibility, and enhanced carotenoid stability makes these extracts appealing for use in food product fortification.