Although the great restaurants of France are thriving and their chefs are national celebrities, there has been a marked decline in that nation's standard of eating. According to two masterful French cooks on a visit here last week, the pace and price of moder life have accomplished something that war and Depression never could: Eating well is a secondary concern for many in the land that coined the term gastronomy.

Georges Blanc, whose Chez La Mere Blanc restaurant in Vonnas rates two stars in the Michelin Guide, and Pierre Verot, a specialist in charcuterie, were here to do demonstrations and present special dishes at a fashion show.

Blanc deals with restaurant-goers and tourists from abroad, while many of Verot's clientele are local housewives; so their points of view diverge frequently. But both cited such familiar themes as lack of time, more women working outside the home and the combined influence of the automobile and superhighways as causes for the changing profile of the French national diet.

"People today are spending a lot less for everyday life and spending more on leisure and pleasure," said Verot, whose Maison Verot provides pates, sausages, catering services and even wines for natives of the industrial city of St. Etienne. A few search out and demand the best food, but many French settle for mundane meals or products that are faster to obtain or easier to prepare. "There is a gap" in the quality level they demand, Verot acknowledged.

While many American women and men are using leisure time to craft French culinary creations at home, the French themselves have been exploring supermarkets and fast-food restaurants on the autoroutes, and eating frozen foods fromlarge refrigerators or freezers they have purchased only recntly. Louis XIII may have been the last hobbiest cook in the French upper and middle classes. Bread is purchased at the bakery instead of being made at home. A pate or hors d'oeuvre for company is bought at a shop such as Verot's.

Maison Verot has changed with the times, not by reducing quality, but by breaking out of the traditional small shop mold. Verot and his brother sell wine, cater receptions in a St. Etienne mansion on Sundays, the day the shop is closed, and have begun manufacturing products. Instead of being solely dependent on day-to-day business in the neighborhood, they are able to profit from the special-occasion customer as well.

"People go to a luxury restaurant for a special occasion," Verot said. "For that event the price doesn't matter. But each day I have to provide s good pate for a reasonable price to a woman on a budget."

Verot's 19-year-old nephew, Jean-Marc, accompanied him as an assistant. He has been learning the manufacturing end of the craft for the past three years. But he had another purpose. As a business school student, he wanted to observe American food businesses at first hand. He plans to return to the United States for sales training as part of the five-year course, then will work in the sales arm of the family firm.

Blanc's Chez La Mere Blanc is a luxury restaurant with modern hotel accommodations. It does a lively business even though it is not near any large city and has been rumored as a candidate for the top, three-star Michelin rating. Understandably, his defense of French eating habits was more spirited than his colleague's.

Blanc spoke of a revival of interest in real - as opposed to fabricated - food and an opening up of the great restaurants to people of varying ages and social classes. "I am optimistic," he said, pointing to economic problems that have beset autoroute and fast-food eateries. According to the chef, these places are losing business due to the substandard quality of the food. With less business and inflation, prices go up, which results in even less business.

Although Chez La Mere Blanc has been in his family for a hundred years, the chef sees it and some others tagged with the label of nouvelle cuisine on the leading edge of a great restoration of food appreciation.

"Before, you had classic recipes made all over France," he said, "sometimes well done, sometimes badly done. Today you find the personality of the cook expressed wherever you go. There is more finesse in what we do now and more importance is attached to the products we use. You can sell quality in France today, to cooks and to the public that come to our restaurants. They are young. They know more. They demand new dishes.I experiment all the time and change my menu every three or four months."

Blanc also seeks to capitalize on his name by selecting and selling wine fromthe bearby Beaujolais and Macon regions and by merchandizing food products. His trip here and on to New York at a busy season for the restaurant was prompted by a desire to locate American distributors.

Balnc had already crowded in half-day of tourism last Thursday afternoon when he and the Verots made a routine tour of markets and specialty shops in search of ingredients for demonstrations they would do at Bloomingdale's and for display pieces to be shown and tasted at a reception Saturday night.

It soon became evident that the essential ingredients were not available for one Blanc favorite, fricasse of Bresse chicken breast in red wine with wild mushrooms and fresh truffles. Nor were local oysters, rockfish, leaf spinach, tarragon or chives. Alternatives were discussed, a home herb garden was located and the cooks were guided to the French Market, where there was no language barrier to clear.

By the time they had collected two sucking pigs that would be boned and stuffed, 3 whole 18-pound salmons, chickens, ducks, eggs, butter, wine, vegetables, two jars of truffles and eight cans of mousse de foie gras, the grocery bill was $2,500. Barbara Kafka, the editor of Cooking Magazine who acted as guide and interpreter for the cooks, said the expenditures were "modest."

At any rate, whatever Bloomingdal's - the sponsor - spent on supplies, the store clearly saved money on labor. Blanc and the Verots worked at a furious rate on Friday to produce an enormous amount of food for the reception. They brought their purchases to the Georgetown kitchen of cooking teacher Carol Mason and struggled successfully to overcome a language barrier and the handicap of utensils too small for their needs.

The pigs and ducks were separated from their skins and bones. A huge pile of tomatoes became a sauce. Jean-Marc Verot acted as a human food processor, cutting and chopping mounds of chicken and pork. His uncle tried out a real food processor and used the grinder attachment on an electric mixer. But Pierre Verot, whose intensity hides a finely honed sense of humor, found it easier to work by hand. As he flayed away at a tub of sausage with both hands to mix in seasonings, he grinned and commented. "One has to come to America to do everything by hand."

Georges Blanc, youthful-looking, careful and seemingly unflappable, wrestled briefly with a foreign can opener and quietly washed up as he worked. "Do you have to do the dishes at Chez La Mere Blanc?" he was asked.

"It happens," he responded. "In our business sometimes you have to do everything."

Verot called for a small sack he had brought from France. It contained spices and knives. Blanc, who soon had clarified several pounds of butter and made a puree of potatoes, turned his attention to mincing shallots and making a tomato sauce. Pierre Verot trying out English, pointed to a duck and explained "not today but demain we will eat this . . ." Stuck, he paused then said, "this quack-quack."

"Duck," he nephew told him. "Duck, like Donald."

In time a stock had been made and the suckling pigs were stuffed, shaped and taken off to the Watergate Restaurant's large ovens to cook. Their work done, the cooks finally were free to see a bit of Washington so they were free to see a bit of Washington so they went to a French restaurant for dinner.

Saturday, too, was more work than play. Demonstrations (Blanc's was held in a miserably inadequate space without an overhead mirror or seating in Bloomingdale's White Flint store), more preparation and finally the reception. One of Verot's pigs was auctioned off. The food they had prepared disappeared in a fraction of the time it had taken to prepare.

This week after a taste of America, they are back at their own stoves, doing their bit to encourage a French gastronomic renaissance. Here are several recipes they left belund. GEORGES BLANC'S COULIS DE TOMATES

A coulrs is more concentrated than what we know as tomato sauce, yet not nearly as thick as tomato puree. The chef does not favor proportions for this recipe, but prefers to vary it according to mood and the quality of the tomatoes.Take a least a pound of ripe tomatoes (more if you have storage space as this has many uses).

Peel the tomatoes, cut and seed them and put them into a pot with a little oil, I unpeeled clove of garlic per pound, half a bay leaf and some fresh (but not dried or ground) thyme. Cook over medium heat until the tomatoes are soft. Stir from tiem to time, breaking up tomatoes as you do. When tomatoes have reduced, pour into a colander over a bowl and let drain. Return liquid to the bowl and reduce until it is syrupy. Discard garlic and herbs, mix tomatoes back into juice, season with salt and pepper to taste and set aside to cool. Use as a sauce or in other recipes as indicated below. MARINADE DE BLANC DE POULAND ALEXANDRE (4 or 8 servings) 4 whole chicken breasts, on the bone with skin 5 Quarts chicken broth (about). 1 ripe tomato with good color, peeled and flesh cut from outer rim only. Less than 1 cup of frozen frenched green beans (or very young beans, blanched, cooled and sliced fbeans (or very young beans, blanched, cooled and sliced fine) 1 cup Saucier glace de viande* (or 1/2 to 3/4 cup homemade glace de viande)(FOOTNOTE)

*Sold in local specialty stores.(END FOOT) 1/4 cup red wine vinegar 5 tablespoons good olive oil 1 tablespoon coulis de tomatos 1 drop Worcestershire sauce 2 cloves Pinch thyme 1 shallot, peeled and finely chopped Drop or two of Cognar Juice of 1/2 lemon 2 heaping tablespoons chopped chives 1 tablespoon fresh tarragon (if using dry tarragon, steep 1 teaspoon in the vinegar before beginning preparation) Salt and Freshly ground pepper 1 truffle, cut in rounds or matchsticks (optional)

Poach chickens in broth until just cooked. Heat glace de riande . Mix with vinegars, oil, coulis , Worcestershire, cloves, thyme, shallot, Cognac, lemon juice, chives, tarragon, salt and pepper.

Pour some of this marinade on a serving platter. Drain, cool, skin and bone the breast meat. Make a pinwheel pattern on the serving plate with the chicken pieces. Cut tomato and string beans in strips and decorate spaces between breast with these strips. Cover with marinade, the add optional truffle. This can sit for a couple of hours in a cool place before serving, but do not refrigerate it.

Sold in local specialty stores. PIERRE VEROT'S POTATO PANCAKES (Makes 12 to 16) 4 medium potatoes (not Idaho or new) 4 large eggs Salt and pepper to taste Cooking oil Peel potatoes and grate them in a food processor. Remove potatoes, change to slicing blade and work potatoes with eggs and seasoning til creamy and only small bits remain.

Heat oil an an omelet pan, or one of a similar size, until it begins to smoke. Add about 1/4 cup of batter and cook until it is golden brown on one side (about 2 minutes). Flip or turn pancake and cook on other side until golden. The pancakes are less likely to break if they are flipped. Practice before trying them on company. Serve as a first course or in place of a starchy vegetable.

Lacking a food processor, the potatoes may be grated by hand on a fine grater. The consistency may be somewhat different.