Green Beans
Snap beans, string beans, wax beans
Green beans and wax beans are high in dietary fiber, a moderate source of vitamin A derived from deep yellow carotenes, hidden by their green chlorophyll. Wax beans have very little vitamin A because their color comes from carotenes with little or no vitamin A activity. They have some vitamin C.
One-half cup cooked green beans has two grams dietary fiber, 437 IU vitamin A (18 percent of the RDA for a woman, 15 percent of the RDA for a man), and 6 mg vitamin C (8 percent of the RDA for a woman, 7 percent of the RDA for a man).
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Raw, microwaved, or steamed just to the crisp-tender stage, to preserve their vitamin C.
Green beans were once better known as string beans because of the “string” running down the back of the bean.
Today, that string has been bred out of most green beans, but you may still find it in wax beans and in haricots verts, the true French green beans.
To prepare green beans and wax beans, wash them under cool running water, pick off odd leaves or stems, snip off the ends, pull the string off wax beans or haricots verts, and slice or sliver the beans.
Cooking reduces the amount of vitamin C in green beans and wax beans but does not affect the vitamin A, which is insoluble in water and stable at normal cooking temperatures.
Green beans will change color when you cook them. Chlorophyll, the pigment that makes green vegetables green, is sensitive to acids. When you heat green beans, the chlorophyll in the beans will react chemically with acids in the vegetable or in the cooking water, forming pheophytin, which is brown. The pheophytin makes the beans look olive-drab.
To keep green beans green, you have to keep the chlorophyll from reacting with acids. One way to do this is to cook the beans in a large quantity of water (which will dilute the acids), but this increases the loss of vitamin C. A second alternative is to leave the lid off the pot so that the volatile acids can float off into the air.
The best way may be to steam or microwave the green beans very quickly in very little water so that they hold onto their vitamin C and cook so fast that there is no time for the chlorophyll to react with the acids.
Canning and freezing. Commercially frozen green beans and wax beans have virtually the same nutritional value as fresh beans. Canned beans, however, usually have added salt that turns the naturally low-sodium beans into a high-sodium food. Canned green beans and wax beans have less vitamin C than fresh beans.
