Vegetables and their by-products: total phenolic compound content, total flavonoids, and antioxidant activity

ABSTRACT There is an underutilization of bioactive compounds, given the losses and daily waste of vegetables throughout the entire production chain. Accordingly, the objective of this study was to quantify the content of phenolic compounds and antioxidant capacity in different parts of vegetables. Analyzes were performed on five vegetables (zucchini, eggplant, broccoli, green cabbage and green beans) from conventional cultivation. The levels of total phenolics, total flavonoids, and antioxidant capacity were obtained by spectrophotometric methods. Except broccoli, the analyzed by-products had levels of bioactive compounds and antioxidant capacity equal to or greater than the traditional parts of vegetable. Broccoli florets stood out with the highest levels of total phenolics (141.22 mg GAE/100 g), total flavonoids (137.38 mg CE/100 g) and antioxidant capacity (588.3 µmol TEAC/100 g). In contrast, the lowest levels were observed in zucchini pulp (25.44 mg GAE/100 g; 13.03 mg CE/100 g; 69.78 µmol TEAC/100 g). Therefore, the importance of full consumption of vegetables is reiterated. By-products can also be used to enrich preparations.