Application of deep eutectic solvents as a green and biodegradable media for extraction of anthocyanin from black carrots

Deep eutectic solvents (DESs) not only could keep a high extraction efficiency, but also could easily be applied to pharmaceutical and food products. This study aimed to set out an eco-friendly technique for the anthocyanin extraction from natural sources. In this study, DESs coupled with ultrasound-assisted extraction (UAE) were considered as an alternative green method to classical applications. The choline chloride-based DESs was prepared with the hydrogen bond donor. The conventional, UAE and DES extraction methods were studied and compared. Citric acid was selected as the most promising hydrogen bond donor for the preparation of DES. The results showed that the biodegradability of all tested DESs was >80% after 28 days. Based on the analyses, it could therefore be assumed that all of the analysed DESs were biodegradable green solvents. The results of FT-IR revealed that pure choline chloride demonstrated several functional groups and many of these functional groups coexisted after DES formation. Thermogravimetric analysis (TGA) showed that all the DESs and their components were degraded in a single stage and the polymeric colour ratio was lower if acid was present in the DES composition. The results indicated that the developed method could be regarded as a sustainable, effective, and green approach for anthocyanin extraction