The effect of cooking on total polyphenolic content and antioxidant activity of selected vegetables

The aim of this study to investigate the effect of different cooking methods (boiling, steaming, stir-frying, and microwaving) on the total polyphenolic content and total antioxidant activity of selected vegetables (beet, red cabbage, broccoli, white cabbage, black radish, kale, turnip, and red radish) from Turkey. A wide variation on total phenolic content was observed in raw vegetables, ranging from 44.94 ± 0.47 (beet, Beta vulgaris L. subsp. vulgaris) to 350.94 ± 5.18 (red radish, Raphanus sativus L.) μg gallic acid equivalent/mg of sample. Considering uncooked vegetables, the order of total antioxidant activity determined by β-carotene bleaching assay was beet > red cabbage > broccoli > white cabbage > black radish > kale > turnip > red radish. In DPPH• assay, kale had an exceptionally high antioxidant activity followed by red cabbage, broccoli, turnip, black radish, beet, white cabbage, and red radish.