Vegetable food processing results in by-products that, when wasted, contribute to increase the environmental pollution. However, studies reveals that food by-products have a potential source of healthful bioactive compounds. The aim of this study was elaborate flours of red beet (Beta vulgaris L.) (FB) and Tommy Atkins (Mangifera indica L.) (FM) and analysis their antioxidant activity and total phenolic compounds, in order to enhance residues regularly discarded. Husks of red beet and mango were obtained in a fruit and vegetable market from Rio de Janeiro were sanitized in a 2.5% sodium hypochlorite (NaClO) for 10 minutes, washed, them crushed and immediatelly dried in a ventilated oven for 6h at 70°C for FcB and for 4h at 60°C for FM, and finely ground. For the analysis of antioxidant activity (DPPH, ABTS and FRAP) and total phenolic compounds (Folin-Ciocalteu) were obtained extracts of ethanol:water (50:50) and distiled water. The ethanol extract of FM obtained the best antioxidant profile for DPPH (585.7 µM Trolox/100g), FRAP (150.0 µM Ferrous Sulfate/g), ABTS+ (11,418.5 µM Trolox/100 g) and total phenolic compounds (8,4 mg EAG/g) in comparision to the aqueous extract. On the other hand, ethanol and water extracts from FB obtained similar results for DPPH (275.4 and 276.2 µM Trolox/100g) and total phenolics (2.4 and 3.0 mg EAG/g), repeating the profile found in FM for FRAP (96.0 µM Ferrous Sulfate/g) and ABTS+ (9,081.5 µM Trolox/100 g). The result confers on FB and FM relevant levels of bioactive compounds in these methods. Therefore, at the same time as we find possible ways to reduce food waste and make the circular econnomy a reality, we increase the availability of ingredients foods with high antioxidant potential, reintegrating these foods into a human ingestion.