THINGS have heated up at the White House since the Kennedy administration, at least in the kitchen. Or the crab has heated up, anyway.

Last fall the White House was sending out a recipe for crab and artichoke casserole to citizens who requested a sample of White House taste. But by December there were complaints about such an expensive recipe representing the Reagans, and so the recipe was no longer made available.

The finger pointing began, pitting East against West. The first lady's press secretary, Sheila Tate, said this week that the recipe hadn't come out of the East Wing, her domain, but that it came from the president's correspondence office in the West Wing. The West Wing had no comment. "It was a mistake early in the administration to send out a variety of recipes," she added. Furthermore, the crab casserole didn't even reflect President Reagan's taste, she said, because if he had his way he would eat macaroni and cheese and coconut cake every day.

She hardly needs to be apologetic, though. The Reagan White House is not the first to lend its backing to the luxurious crustacean. We recalled a Kennedy favorite combining crab and artichoke, and through the office of Letitia Baldridge, who had been Jacqueline Kennedy's social secretary, obtained that earlier administrations' recipe (subsequently published in "The White House Chef Cookbook" by Rene' Verdon) for Salade d'Artichaut Au Crabe Froide, or chilled artichoke and crab meat salad.

Still, there are significant differences. The Reagans' crab dish, as reprinted in the fifth edition of "The First Ladies Cook Book," is not only titled in English and served hot, it specifies canned or frozen crab and canned artichoke hearts.

Here are the recipes for both of them. KENNEDY SALADE D'ARTICHAUT AU CRABE FROID (6 servings) 1 cup diced cooked artichoke hearts 1 cup crab meat 1/2 cup heavy cream, whipped 1 cup mayonnaise 1/2 cup ketchup 1/2 teaspoons worcestershire sauce Salt and pepper to taste

Combine artichokes and crab meat and chill. Mix whipped cream with mayonnaise, ketchup, worcestershire sauce, salt and pepper. Chill. At serving time, combine the sauce with crab mixture. From "The White House Chef Cookbook" REAGAN CRAB-ARTICHOKE CASSEROLE (4 to 5 servings) 3 tablespoons butter 3 tablespoons flour 1 1/2 cups milk 1 teaspoon salt 1/8 teaspoon pepper 1/4 teaspoon worcestershire sauce 2 cups canned or frozen crab meat 4 hard-cooked eggs, quartered 14-ounce can artichoke hearts, drained 1/3 cup grated parmesan cheese

Melt butter in saucepan. Stir in flour until smooth. Gradually add milk and seasonings and cook over low heat, stirring constantly, until mixture is thickened. Remove from heat. Stir in crab meat. (If using frozen, make certain it is thawed.)

Place eggs and artichoke hearts in bottom of greased 1 1/2-quart casserole. Pour crab-cream sauce over all. Sprinkle with cheese. Bake in a 350-degree oven for about 30 minutes. From "The First Ladies Cook Book"

The dangers of sodium bisulfate--commonly used as a freshener and antibrowning agent for fresh fruits and vegetables, particularly for salad bars--have had restaurateurs collectively wringing their hands. The National Restaurant Association asked its members to discontinue use of the chemical, but they have hesitated to give up that verdant fresh look. The answer is astonishingly simple, says Richard Hopkins, a Washington area restaurant consultant: good ol' non-threatening Vitamin C, or ascorbic acid. Crystalline ascorbic acid, readily available, can be dissolved in the water used for washing produce (two tablespoons per gallon, recommends Hopkins), or greens can be soaked until any rust spots disappear. Anybody who has ever sliced an apple and squeezed a little lemon juice over it to keep it from browning can attest to this method.

Is there a future for Maryland sangria? That's to be discovered at the Boordy Vineyards Spring Open House on Sunday, May 22. The annual event, this year to celebrate the release of Boordy's 1982 seyval blanc, will be 11 a.m. to 6 p.m. at the vineyard, 12820 Long Green Pike, Hydes, Md., in northeastern Baltimore country. Admission is $2.50, which includes guided tours, samplings of current bottlings and ambling through the vineyards, as well as free sangria. Boordy provides the music; you provide your own picnic.Call 301-592-5015.

If Maryland sangria has a future, maybe Virginia groundnut stew does, too. May 21 (10:30 a.m. to 7 p.m.) and May 22 (noon to 7 p.m) are the days to sample this West African staple, along with Cambodian sweet stuffed acorn squash, Serbian roast lamb, Vietnamese spring rolls and a couple dozen other countries' specialties at the Northern Virginia Folk Festival. Again the music will be provided, along with folk dancing. Admission is $1 for adults, 50 cents for preschool children and senior citizens, and the location is Thomas Jefferson Community Center, 3501 Second St. South, just off Route 50 and Glebe Road in Arlington.

Low-sodium diets have given new life to herbophiles, as one can discover at the annual herb day of the Potomac Unit of the Herb Society of America. As always there will be lectures and demonstrations, sales of everything herbal from tussie mussies to wreaths, guided tours of the National Herb Garden and a box lunch available to buy. Plus, this year, talks on herbs in low-sodium diets. Admission donation is $2 for the events, which are May 19 from 10 a.m. to 3 p.m. at the National Arboretum, Bladensburg Road and R St. NE. For more information call 256-6868 or 860-4681.