Which antioxidants are stable when cooking vegetables

Some vegetable cooking methods may be better than others when it comes to maintaining beneficial antioxidant levels, according to a new study in the Journal of Food Science, published by the Institute of Food Technologists. Results showed that, depending on the vegetable, cooking on a flat metal surface with no oil (griddling) and microwave cooking maintained the highest antioxidant levels.

Fruits and vegetables are considered to be the major contributors of nutritional antioxidants, which may prevent cancer and other diseases. Because of their high antioxidant levels and low-calorie content, consumers are encouraged to eat several servings of fruits and vegetables daily.

Researchers examined how various cooking methods affected antioxidant activity by analyzing six cooking methods with 20 vegetables. The six cooking methods were boiling, pressure-cooking, baking, microwaving, griddling and frying. Their findings showed the following:

• The highest antioxidant loss was observed in cauliflower after boiling and microwaving, peas after boiling, and zucchini after boiling and frying.
• Green beans, beets, and garlic were found to keep their antioxidant levels after most cooking treatments.
• The vegetables that increased their antioxidant levels after all cooking methods were green beans (except green beans after boiling), celery and carrots.
• Artichoke was the only vegetable that kept its high antioxidant level during all the cooking methods.

Griddle- and microwave-cooking helped maintain the highest levels of antioxidants, produced the lowest losses while “pressure-cooking and boiling [led] to the greatest losses,” says lead researcher A. M. Jiménez-Monreal. “In short, water is not the cook’s best friend when it comes to preparing vegetables.”