Some Diminishment of Nutritional Value . . .

Cooking generally reduces the nutritional content of fruits and vegetables. There are some important exceptions to this rule, but the levels of most vitamins, antioxidants, and other beneficial substances are diminished by the combination of high temperatures, uncontrolled enzyme activity, and exposure to oxygen and to light. They and minerals can also be drawn out of plant tissues by cooking water. These losses can be minimized by rapid and brief cooking. Baked potatoes, for example, heat up relatively slowly and lose much more vitamin C to enzyme action than do boiled potatoes. However, some techniques that speed cooking—cutting vegetables into small pieces, and boiling in a large volume of water, which maintains its temperature—can result in increased leaching of water-soluble nutrients, including minerals and the B and C vitamins. To maximize the retention of vitamins and minerals, cook small batches of vegetables and fruits in the microwave oven, in a minimal amount of added water.