Optimized Production of a Hesperidin-Enriched Extract with Enhanced Antioxidant Activity from Waste Orange Peels Using a Glycerol/Sodium Butyrate Deep Eutectic Solvent

Abstract

Citrus processing side-streams are largely represented by waste orange peels (WOP), and there are several techniques developed for polyphenol extraction from WOP; yet, there are a significant lack of methodologies based on non-conventional, green solvents. On this basis, this study was performed to assess a deep eutectic solvent (DES) synthesized with glycerol and sodium butyrate, for its capacity to extract WOP polyphenols. Optimization of the process was carried out using a response surface methodology, which revealed that a maximum total polyphenol yield of 73.36 mg gallic acid equivalent (GAE) g−1 dry mass (DM) could be achieved with a solvent system of DES/water (80% w/w), a residence time of 120 min, and a temperature of 90 °C. Using these settings, the polyphenol extraction from WOP with the DES/water solvent system was found to have outstanding performance compared to aqueous or hydroethanolic extraction, while the extracts generated possessed significantly enhanced antioxidant properties. The chromatographic analyses of the extracts demonstrated that the DES/water extract was particularly enriched in hesperidin (21.81 mg g−1 dry mass), a bioflavonoid with promising pharmaceutical potential. This is a first report on the use of this particular DES for WOP polyphenol extraction, which may be used to produce hesperidin-enriched extracts, by implementing the methodology developed.