Choline chloride-based natural deep eutectic solvents for the extraction and stability of phenolic compounds, ascorbic acid, and antioxidant capacity from Citrus sinensis peel

Abstract

Orange peel is a great source of bioactive compounds like phenolic compounds and ascorbic acid (AA), which have high antioxidant capacity. New methodologies have called attention for their extraction employing greener solvents, as natural deep eutectic solvents (NADES). There is a lack of information about the protective role and stability of bioactive compounds in NADES. This study aims to find the most suitable NADES for the extraction of bioactive compounds from orange peel. The first step was screening eight NADES, determining its antioxidant capacity (AC), AA, total phenolic content (TPC) and total flavonoids (TFC). The extract stability was monitored during storage for twelve days, determining phenolic compounds, AA, and AC. The results showed that choline chloride:malic acid (ChChl:MA) (TPC: 1053 mgGAE/100 g. TFC: 94.7 mg/100 g. AA: 430 mg/100 g), and choline chloride:glycerol (TPC: 903 mgGAE/100 g. TFC: 169 mg/100 g. AA:416 mg/100 g) were the most suitable NADES for the extraction of bioactive compounds. AA and phenolic compounds are more stable in ChChl:MA. The capacity of NADES to improve the stability and enhance the AC of the extracts makes these formulations suitable for their application in the food formulations avoiding the solvent elimination process.