Avoid: Withered or dry beans; they have been exposed to air, heat, or sunlight and are low
in vitamin A.
Storing This Food
Wrap green beans and wax beans in a plastic bag and store them in the refrigerator to protect
their vitamins and keep them from drying out.
Preparing This Food
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.
What Happens When You Cook This Food
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 chloro-
phyll 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.
How Other Kinds of Processing Affect This Food
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.
Medical Uses and/or Benefits
Green Beans