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Corn, fresh

Why Eat It
Varieties
Availability
Shopping
Storage
Preparation
Nutrition Chart


Why Eat It

Corn, a high-carbohydrate food, has been an important nutritional resource for thousands of years, although the corn of our ancestors was a starchier, less tender version of today's corn. Corn that is cultivated today falls into two main categories: sweet corn and field corn. Sweet corn, which was not widely cultivated until the mid-1800s, is harvested at an immature stage, so that its kernels are tender and juicy; at their peak of flavor, they contain 5% to 6% sugar by weight. Field corn, on the other hand, is picked at a mature, predominantly starchy stage, dried to a more hardened state, and used in a multitude of ways--as livestock feed and, after refining, in a wide array of processed foods and drinks, from cornstarch to whiskey (as well as in many nonfood products, such as fuel, paper, and plastics). Popcorn is a field-type corn with thick-walled kernels; when heated, steam is trapped inside the dried kernels, causing them to "explode."

Presumably, it is the sugar in sweet corn that accounts for its popularity among Americans. They eat about 25 pounds of it per person annually, most of it frozen or canned. Generally speaking, canned and frozen corn are about equal in nutritional value to fresh corn. However, frozen corn--which includes corn on the cob (whole ears or sections) and cut corn kernels--sometimes is packaged in a butter sauce or in other rich ingredients that increase its fat and sodium content. Canned corn usually has both salt and sugar added, making it somewhat higher in calories and sometimes substantially higher in sodium than fresh cooked kernels. Vacuum-packed canned corn is crisper and more like fresh corn than other canned types. Despite its name, canned "cream-style" corn has no milk or cream added; it is prepared with sugar and cornstarch, which further raise its calorie (but not its fat) content.

Varieties

Most varieties of sweet corn--there are more than 200--have yellow kernels; smaller local crops often include white or bicolor corn (which has a mixture of white and yellow kernels).

Recent work in corn genetics has produced varieties called "supersweet," bred to have more than twice the sugar content of regular corn. Much of the corn now grown in Florida--the leading producer of fresh market sweet corn--is a supersweet variety known as "Florida Sweet." Some supersweet varieties also convert their sugar into starch more slowly after the corn is picked--a highly desirable trait in corn that must be shipped to distant markets. Supersweets like standard sweet corn, may be yellow, white, or bicolor.

Availability

Although it is traditionally a summer vegetable, you'll find fresh sweet corn in many supermarkets all year round. Most of the corn sold from December through May comes from Florida, where the harvest season runs from fall through spring. Corn is harvested in much of the rest of the country in the late summer and early fall, and at these times you will probably find locally grown corn in your market. New York and Ohio are among the largest producers of summer sweet corn.

Shopping

For corn, freshness means staying cool, since warmth converts the sugar in the kernels into starch. In the supermarket, therefore, corn should be displayed in a refrigerated bin; at a farmstand or a farmer's market, it should be kept in the shade or on ice. Shop early in the day for the best selection of locally grown corn; ideally, it should have been picked the morning you buy it. The corn should not be piled high in the bin, or it will generate its own heat, hastening the conversion of sugar to starch. If you're making a trip to the country to get fresh-picked corn, take along an ice chest or cooler in which to pack it.

Check that the husks are fresh-looking, tight, and green (not yellowed or dry); strip back part of the husk to see whether tightly packed rows of plump kernels fill the ear. The kernels at the tip should be smaller (large kernels at the tip are a sign of overmaturity), but still plump rather than shrunken. Pop a kernel with your fingernail: Milky juice should spurt out. If the liquid is watery, the corn is immature; if the skin of the kernel is tough and its contents doughy, the corn is overripe. The stalk of a freshly picked ear of corn will be green and moist; if it is opaque and white, or dry and brown, the corn is several days old and will not be very sweet. The silk should be moist, soft, and light golden, not brown and brittle.

Storage

To best enjoy fresh corn's flavor, "the sooner the better" is a rule of thumb. Try not to store corn for more than a few hours; cook it as soon as possible after it is picked, and be sure to refrigerate it the moment you get home if you are not cooking it immediately. (At room temperature, sweet corn loses its sugar six times faster than at 32°F--up to half its total sugar in one day.)

If the corn is unhusked, leave it that way to keep it moist until you are ready to cook it. If the ears are already fully or partially husked, place them in a perforated plastic bag. If you have more corn on hand than you can use within a day or two, parboil it for just a minute or two (this step stops the conversion of sugar to starch); then you can refrigerate it for up to three days. Finish the cooking process by dropping the corn into a pot of boiling water and boiling it for a minute. Or, cut the kernels from the cob and reheat them in a small saucepan.

Preparation

Unless you are grilling or roasting corn in its husk, strip off the husk and snap off the stems (or leave them on to use it as "handles"). Pull off the silk, using a dry vegetable brush to remove strands of silk caught between the kernels.

Getting Corn off the cob: To cut whole kernels from the cob, hold an ear of corn vertically, resting the tip on the work surface. Slide a sharp knife down the length of the cob to slice off the kernels. For cream-style corn, slit each row of kernels with a sharp knife, then run the back of the knife down the length of the cob, to squeeze out the pulp and juice, leaving the skins of the kernels on the cob.

Boiling: There are many schools of thought as to the best way to cook corn on the cob, but two basic rules apply: Do not add salt, as it will toughen the corn (although a little sugar will enhance the corn's sweetness); and cook the corn only long enough to tenderize it--a matter of minutes. One method is to add husked ears of corn to a pot of boiling water, cover it, and let the water return to a boil. Turn off the heat and let stand for five minutes. (You can leave it in the hot water for up to 10 minutes.)

Microwaving: Individually wrap one or two ears of husked corn in waxed paper or place several ears in a covered microweavable dish with 2 to 3 tablespoons of water. Cooking times: for wrapped, three to six minutes; in a dish, 5 to 7 minutes.

Roasting: To roast corn in the husk, first pull back the husks so that you can remove the silk, then replace the husks and tie them with kitchen string. Soak the corn in cold water for five minutes. (If the corn is already husked, you can wrap each one in foil.) Bury the ears of corn in the hot coals of a barbecue fire, or place them on the grill and cook, turning occasionally. To oven-roast corn, place the ears in a 375°F oven. Cooking times: in the coals, 10 to 15 minutes; on the grill, 15 to 20 minutes; in the oven, 20 to 30 minutes.

Steaming: Place whole or cut-up ears of corn in a vegetable steamer and cook, covered, over boiling water. Or, steam-boil them in a heavy pot: Place corn and 1" of water, cover tightly, and bring to a simmer. Cooking time: six to 10 minutes.

Nutrition Chart

Corn/1 cup kernels cooked

Calories
131
Total fat (g)
0.7
Saturated fat (g)
0.1
Monounsaturated fat (g)
0.2
Polyunsaturated fat (g)
0.3
Dietary fiber (g)
3.9
Protein (g)
5
Carbohydrate (g)
32
Cholesterol (mg)
0
Sodium (mg)
8
Folate (mcg)
51


Date Published: 04/20/2005
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