Supercritical CO2 to recover extracts enriched in antioxidant compounds from beetroot aerial parts

Abstract Beetroot is a well appreciated edible root, widely used for sugar and ethanol production, and source of natural colorant. Its aerial parts, leaves and stems, are frequently discarded as animal feed or manure. Therefore, the recovery of bioactive components from these materials is appealing due to abundance of raw material, its low price and poor valorization, allied with the lack of related studies. Soxhlet, maceration, ultrasound and supercritical fluid extraction (SFE) were compared in terms of process yield and extract quality, particularly related to its total phenolic content (TPC) and antioxidant potential. Extracts were compared with standard antioxidant BHT (butylated hydroxytoluene), and the highest TPC values were obtained by SFE with ethanol:water and ethanol as cosolvents, up to 99 ± 4 mgGAE/g extract and 98 ± 6 mgGAE/g extract , for leaves and stems respectively. The bioactive substances extracted from these residues may present a high potential for reused in food or pharmaceutical industries, supporting the closed cycle manufacturing.