BOSTON, MASS. -- Frozen food manufacturers need a new tack. No longer are TV dinners more convenient than haute carryout, pizza deliveries or even supermarkets' own ready-to-go dinners and salad bars. Despite appealing to price-consciousness and calorie-consciousness, frozen main-dish sales have flattened, and those of fancy meals have declined.

Now manufacturers are selling nutrition. They are promoting their entrees as low in fat and cholesterol, sometimes going so far as to make them high in vitamins, minerals and fiber or low in sodium.

Competition has added a new factor, though. Convenience is not enough. Low price is not enough. Low calorie content is not enough. And nutritiousness is not enough. Diners have begun to demand good taste.

Often they aren't getting it.

Tufts University Diet & Nutrition Letter examined about 450 frozen entrees and dinners for their healthfulness, and identified 43 as highly recommended because they contained 300 calories or less, no more than 30 percent of their calories from fat, at least 15 grams of protein, no more than 1,000 milligrams of sodium and a net weight of at least 9 ounces. Then Tufts gathered eight food editors and restaurant critics from around the country to taste them.

Most were awful. And this conclusion came even from a couple of food editors who confessed to frequently eating frozen dinners at home. Those of us who don't have occasion to eat frozen dinners were amazed that they are still so bad. They tasted like canned food, said Dale Curry of the New Orleans Times-Picayune. The worst were those that were low-fat substitutes -- "cheese"-stuffed pastas whose fillings tasted like flour paste rather than cheese, and Legume's Meatless Pepper-Steak with Kofu and Noodles, whose appearance, texture and taste so nauseated the tasters that Sara Pearce of the Cincinnati Enquirer said, "It looks like roadkill."

In all, nine of the list were deemed acceptable by the group, which tasted in two teams. Three of the winners were Weight Watchers products: Sweet 'n Sour Chicken Tenders, Pasta Rigati in Meat Sauce with Cheese, and Chicken a la King. Chicken dishes tended to fare better than others; Budget Gourmet Mandarin Chicken received one team's highest score, and Benihana Chicken in Spicy Garlic Sauce came next. Blue Star Dining Lite's Sauce and Swedish Meatballs was praised for texture and for the flavor of the meatballs (though their shape was eccentric). And two Stouffer's Lean Cuisine lasagnas -- veal and zucchini -- were deemed agreeable (unlike Blue Star's zucchini lasagna, which was leaden with that lowfat "cheese"). Mrs. Paul's Shrimp Primavera had hardly any taste at all, and the shrimp were chewy little bits, but it escaped a poor rating because it was the most beautiful entree in the tasting, its bright peppers contrasting with the pink shrimp and noodles. The other 34 products were rated fair-to-poor.

Since these were mostly 9-ounce dinners, even with sodium levels under 1,000 mg most of them tasted excessively salted. And portions did seem small, though the starchiness did eventually make us feel full on rather little food.

Some of the positive trends we observed were that vegetables are brighter and crisper in most frozen dinners nowadays (and "vegetables" almost always means broccoli and rice). Mushrooms have become the darling of the industry; they were in nearly everything.

Tufts did not evaluate these entrees for their vitamin, mineral or fiber content. Many need to be accompanied by salad and/or a green or yellow vegetable for a balanced meal.

Most of the tasters finished bewildered as to why people would bother to carry, store, reheat and serve such frozen dinners. Steaming a vegetable in the microwave while a chicken breast cooks under the broiler, or boiling a pot of pasta while tomato sauce heats, is at least as quick and far better, we agreed.

Or, as Tufts Newsletter itself recommended in an earlier newsletter, make and freeze your own TV dinners.

Tabletalk

While frozen food companies are increasingly emphasizing low fat, the consumer advocate group Center for Science in the Public Interest reports that Stouffer's Lean Cuisine has fattened up in the last few years. In 1982, says CSPI in its Nutrition Action Newsletter, only one of Stouffer's 10 Lean Cuisine entrees got more than 30 percent of its calories from fat; now half of its 24 selections get more than 30 percent of their calories from fat. Weight Watchers entrees, says CSPI, average 38 percent of their calories from fat.

I wouldn't venture to calculate the fat, and the price is so high you might revert to your credit card, but Wolfgang Puck's frozen foods have successfully fought the tide of frozen inferiority. Frozen foods don't need preservatives, since freezing itself is a preservative. And they need not be made with artificial ingredients. In fact, there is no reason frozen foods can't be as good as restaurant foods, and Puck, chef of Los Angeles' acclaimed Spago restaurant, has proved that. His frozen pizzas cost as much as $9 in supermarkets, but they match or better any pizza parlor pizza; and his desserts -- raspberry-studded chocolate mousse, 12-layer buttercream cake slice, short-crusted apple tart and the like -- are the equal of desserts in any city's top restaurants. Is $3 too much for dessert at home, or $8 to $9 for a pizza? Well, at least you don't have to leave a tip. TUFTSSTART NOTE '? noEND NOTE BROCCOLI-STUFFED SHELLS (8 servings)

3 cups broccoli florets

15-ounce container part-skim ricotta cheese

1/4 cup grated parmesan cheese

2 eggs, beaten

1/4 teaspoon black pepper

1/2 teaspoon nutmeg

1/2 teaspoon oregano

24 jumbo shells, cooked

3 cups tomato sauce

Steam or boil broccoli until crunchy-tender, no more than 5 minutes. Mince and combine with cheeses, eggs and seasonings. Stuff each cooked shell with about 1 tablespoon of the mixture. Place 3 stuffed shells in each of 8 freezer containers. Pour 6 tablespoons sauce over each. Cover, label and freeze. To heat from frozen, bake for 45 minutes at 375 degrees. Serve with a green salad and/or a cooked green vegetable.

Nutrition information per serving: Calories: 235. Calories from fat: 28 percent. Protein: 15 g. Sodium: 490 mg. Cholesterol: 129 mg. From Tufts University Diet & Nutrition Letter

(c) 1988, Washington Post Writers Group