Reuse potential of vegetable wastes (broccoli, green bean and tomato) for the recovery of antioxidant phenolic acids and flavonoids

The aim of this study was to evaluate the potential use of crop wastes (stems and leaves) from broccoli, beans and tomato to extract antioxidant polyphenols. Two different methods of extraction were performed: ultrasound (40 kHz) and conventional with 70 degrees C. In both methods, alkaline and acidic solvents were used. The polyphenol composition was assessed by HPLC-DAD/UV-VIS, and the 2,2-diphenyl-1-picrylhydrazyl assay was used to measure the antioxidant activity. The results showed a significant variation of polyphenol composition and antioxidant activity with the type of sample, pH of solvent and extraction method. Also it was possible to observe that acidic methanol and 70 degrees C enables the extraction of significant amounts of phenolic acids and flavonoids. Based in our results, broccoli, green bean and tomato wastes can be used to extract antioxidant polyphenols, and the use of such wastes to extract polyphenols can be an opportunity to develop an environmental friendly management's systems creating incoming for producers and agro-food sector.