SWEET CORN OF SUMMER

IF price is no object, almost any kind of food can be flown in from halfway around the world, in any season. Except for sweet corn.

This is one delicacy money cannot buy at a snap of the fingers. Sweet corn on the cob must be cooked the day it is picked, served with lots of butter, and eaten before its sugar turns to starch.

But how can anybody tell if corn is still good after a few days?

``Chances are it will be sweet if it hasn't started to dimple,'' said Joe Carcione, TV's ``Green Grocer,'' in a phone interview.

``If you see little dimples in the kernels it means the corn is starting to lose its sugar,'' Mr. Carcione says.

``If you can get your corn the day it's picked at a farmer's stand, that's ideal. But when buying it at the supermarket, be sure you're getting it from a refrigerated counter.''

Although corn comes in several colors, the sweet corn for eating off the cob comes with either yellow or white kernels or a combination of both, called bi-color corn.

``There's no question, white corn is the favorite with Floridians,'' says Ann McDuffie, food editor of the Tampa Tribune, ``although both the white `Silver Queen' and yellow corn are available in the supermarkets. I've never seen any bi-color corn in any of our stores here in Florida,'' she said.

New Englanders like the two-color corn best of all. With their mixture of yellow and white kernels, the two-color varieties have names like ``Butter and Sugar,'' ``Sprite,'' ``Harmony,'' and ``Carnival.''

Later in the season New Englanders will buy ``Sweet Sal'' and ``Sweet Sue,'' also bi-colors, and some growers have a two-color corn called ``Burgundy Delight'' that is a smaller ear, but very sweet, and gets its name from a dark reddish tinged husk.

Of course, there are lots of corn-lovers who don't bother about color or names. They just want corn as fresh as possible. The bottom line, in this case, is how long it takes to get from corn field to table.

Always buy fresh corn that's just been picked at a local farm, or corn that's been kept in a cool place. Corn from other areas will be fine for dishes using cut or scraped corn.

For the best flavor, use fresh corn the day you buy it. Keep it in the refrigerator until ready to cook it.

The tip-off for freshly picked corn is the stem. If it's a damp, pale green, the corn has been picked within the day. After 24 hours, the stalk turns opaque and chalky. Longer than that, it gets brown.

And when buying corn, ask for the extra sweet variety. It holds the sweetness longer.

However they buy it, Americans enjoy corn in many ways.

There is popcorn, of course, and corn dogs, which are hot dogs on a stick dipped in cornmeal batter and deep-fried.

Frozen corn, canned kernels, and creamed style corn are available in every store and are used for creamy corn puddings, chowders, fritters, hush puppies, and even corn cob jelly.

One excellent cookbook, ``A Book of Vegetables'' by Marina Stern (currently out of print but due in reprint this fall), lists 15 or more recipes for corn dishes (more than for potatoes), from corn salads, soups, and breads to corn pudding with raisins.

Corn on the cob is the most popular of all, and whether or not you provide little handles for help in chewing the kernels off the cob, be sure to serve plenty of butter and extra napkins. Boiled Corn On The Cob

Drop shucked corn into a pot of unsalted boiling water and boil 4 minutes. Cooking time is between 4 and 8 minutes, depending on size and maturity of corn. After 4 minutes, remove an ear and taste it. It should be slightly crisp. Drain and serve with plenty of butter, salt, and pepper.

Another favorite method is to bring a pot of unsalted water to boil. Add husked corn and when water returns to the boil, cover and remove from heat. Let corn remain in water for at least 5 minutes. It can stay in the water 20 minutes without becoming tough. Grilled Corn

This has a fine nutty flavor. Pull back husks but do not remove. Remove silk, then pull husks back up and twist or tie in at tips.

Soak corn in a large pot of cold water, tied with husks on, at least 20 minutes. Cook over moderately hot barbecue coals, about 4 inches from heat, 15 to 20 minutes, depending on corn size. They are done when husks are beginning to scorch on all sides and inside is steaming. Serve with butter and salt.

Or prepare as for grilling. Place on rack in 400 degree F. oven. Cook 20 to 25 minutes, depending on size. Foil Method

Remove husks and silk. Brush corn with melted butter. Wrap each ear in foil and roast on a hot grill 15 to 20 minutes or in the oven 20 to 30 minutes. Huntley's Lime Butter 1 1/2 sticks soft butter 2 tablespoons fresh lime juice Salt to taste 1/4 to 1/2 cup fresh table salsa (spicy tomato sauce), optional

Using a fork and a small bowl, mash softened butter with lime juice, adding juice a tablespoonful at a time. Incorporate salt now, or leave it to be sprinkled on later.

The option of adding fresh salsa to the lime butter comes from a Southwestern friend, Carl Fowler. He melts butter in a small pan and stirs in salsa, then serves it warm at the table. Cumin Butter

Melt 4 tablespoons unsalted butter over low heat and stir in 1 tablespoon ground cumin. Add salt only if desired. Let steep 5 minutes or so before Serving. Serve with lime wedges. Makes enough for 6 ears of corn. Corn Off The Cob 4 ears fresh white corn cut from cob, about 2 1/2 cups 2 tablespoons butter 3 green onions, chopped 2 to 4 tablespoons chopped canned green chilies 1 fresh or canned jalapeno, chopped for hotness, optional 1/3 cup heavy cream Salt and pepper Shredded Monterey Jack cheese

Save juices from fresh corn as you slice off kernels. Melt butter in 10-inch skillet, stir in onions and chilies, including optional jalapeno. Cook over medium heat just to wilt onion, a minute or two. Add cream, allow to boil 1 minute, stirring, then add corn.

Cover pan and simmer gently 2 or 3 minutes, or until kernels are just cooked. Add salt and pepper to taste. Remove from heat and add cheese. Serve immediately.

Variation: You may add chopped zucchini or other chopped garden vegetables with the corn. A small boiled potato, cut in cubes, chopped sweet peppers, or more onions could also be added, suggests Huntley Dent in his cookbook ``The Feast of Santa Fe.''