Agriculture Reference
In-Depth Information
Green Beans
How do you keep green beans green? Granted, it may not be the most pressing question
of our time, but it is one that cooks everywhere scramble to find an answer to every sum-
mer. Although the method is surprisingly simple, it turns out that sometimes green beans
shouldn't be all that green anyway.
Every green vegetable goes through essentially three stages of green. When it is raw,
the vegetable is a deep but dull green. During the early stages of cooking, the color turns
bright and vibrant. This change occurs as the cell walls soften and the tiny amounts of oxy-
gen and other gases they contain, which cloud the pure color of the chlorophyll, are driven
off. Finally, the green turns olive drab. This happens because of a chemical change in the
chlorophyll, which is partly due to an enzymatic action, but mostly due to acids that either
are introduced during cooking (adding vinegar or tomatoes, for example) or come from the
vegetable itself and are released during cooking.
Since vibrant color is so important, cooks have devised different strategies for getting
around this chemical change. Old French chefs added a bit of baking soda to the water. This
helps preserve the green, but it also speeds the breakdown of the plant's cellulose, making
the texture slimy. Some modern chefs insist that cooking in very heavily salted water will
help. There doesn't seem to be any scientific basis for this claim, although it probably does
no harm and will certainly help the seasoning of the vegetables. The best way to avoid olive
drab vegetables is to cook them in plenty of water (to dilute the acids that are released); to
make sure the water returns to the boil as quickly as possible (this will finish the cooking
more quickly); and to cook them briefly - then, if possible, plunge them into ice water as
soon as they are done (this stops the cooking process immediately).
Although a vibrant green color is usually desirable, there are times when it can be for-
gone in favor of flavor. In the case of green beans, for example, the importance of pre-
serving the color depends largely on what kind of bean you're cooking.
The green bean is a legume that is harvested when immature. If green beans are left to
grow to maturity, the seeds inside will swell to nugget size, and the tender pods will toughen
and become coarse (as any gardener who has ever gone on summer vacation will readily
attest).
