Synergistic use of NADES and assisted extraction technologies for recovery and stabilization of bioactive compounds in Beta vulgaris L. peels

This work concerns the use of Natural Deep Eutectic Systems (NADES) as sustainable extraction solvents to obtain a bioactive extract, from beetroot peels (BRP), that can be used in food or cosmetic applications. BRP are considered a agrifood waste and often underutilized, although they are rich in phytochemicals with bioactive properties (antioxidant, anti-inflammatory, neuroprotective, and anti-carcinogenic). In this work, the objective was to develop a sustainable, efficient, and extraction method of those valuable compounds, using NADES as solvents and efficient extraction methods. Furthermore, the role of NADES in the stabilization and preservation of these bioactive compounds was also studied. Among the various NADES tested, the one composed of betaine and glycerol (BG), showed the highest extraction efficiency and resulted in extracts with superior antioxidant activity. Optimized extraction conditions were found to be 40°C using a 1:20 solid-to-liquid ratio, with BG. The use of NADES not only improved extraction yield, but also improved the stability of BRP bioactive compounds over a longer period of time. This allows for the extract to be used together with NADES, as a liquid, without the need to remove the extraction solvent. The results confirm that NADES are a promising alternative to conventional solvents and have potential uses in nutraceutical or functional food applications. The study underscores the potential of BRP as a sustainable source of natural antioxidants and highlights a circular approach to waste utilization.