Influence of cooking methods on antioxidant activity of vegetables.

The influence of home cooking methods (boiling, microwaving, pressure-cooking, griddling, frying, and baking) on the antioxidant activity of vegetables has been evaluated in 20 vegetables, using different antioxidant activity assays (lipoperoxyl and hydroxyl radicals scavenging and TEAC). Artichoke was the only vegetable that kept its very high scavenging-lipoperoxyl radical capacity in all the cooking methods. The highest losses of LOO. scavenging capacity were observed in cauliflower after boiling and microwaving, pea after boiling, and zucchini after boiling and frying. Beetroot, green bean, and garlic kept their antioxidant activity after most cooking treatments. Swiss chard and pepper lost OH. scavenging capacity in all the processes. Celery increased its antioxidant capacity in all the cooking methods, except boiling when it lost 14%. Analysis of the ABTS radical scavenging capacity of the different vegetables showed that the highest losses occurred in garlic with all the methods, except microwaving. Among the vegetables that increased their TEAC values were green bean, celery, and carrot after all cooking methods (except green bean after boiling). These 3 types of vegetables showed a low ABTS radical scavenging capacity. According to the method of analysis chosen, griddling, microwave cooking, and baking alternately produce the lowest losses, while pressure-cooking and boiling lead to the greatest losses; frying occupies an intermediate position. In short, water is not the cook's best friend when it comes to preparing vegetables.