There is an increasing concern with the destination of the residues generated by food industry after fruits and vegetables processing. These residues have a high nutritional and economic value due to the fibers, micronutrients, and phytochemicals. In this work, the content of total phenolic compounds, total flavonoids, and the antioxidant activity of the aqueous extract of cabbage (Brassica oleracea L. var. Acephala D.C.) stalk flour (CSF) and pineapple (Ananas comosus) crown flour (PCF) were evaluated. Cabbage stalks and pineapple crowns were obtained from the minimally processed products in fruit and vegetable markets. The flours were prepared after washing, defoliating, fractionating, drying, and grinding in a ball mill. Free PC were extracted with Milli-Q water and bound PC (pellet) after alkaline and acid hydrolysis. Total phenolic content (TPC, mg EAG.100g-1), total flavonoid content (TFC, mg EC.100g-1), and the antioxidant activity (AA, µg EqTrolox.g-1) (DPPH, FRAP, ABTS, and ORAC methods) were determined in both extracts (free and bound). PCF presented higher TPC and TFC (1657.14 and 128.44, respectively) than the CSF (402.25 and 72.39, respectively). PCF extracts, free and bound, showed similar TPC, whereas TFC were similar between CSF extracts. No significant difference was found in AA by DPPH method between the flours (136.21±31.63 to 187.70±33.73). AA was higher in PCF-bound extracts, where ORAC showed the highest values AA (66.92±3.75 mg EqTrolox.g-1). While in CSF, TPC and AA were higher in free extracts. A positive correlation was observed between TPC and AA only in PCF extracts. Water proved to be a good solvent for the extraction of phenolic compounds in PCF and CSF, bringing some benefits such as low cost, safety, and less disposal of organic solvents. However, chemical hydrolysis or alternatively, enzymatic, is still necessary for the extraction of compounds bound to the PCF matrix.