As more and more women enter the work force and look for ways to save time in the kitchen, food advertising plays on these changing lifestyles by playing up convenience foods.

One thing all the advertising has in common is an emphasis on the time-saving qualities of the convenience products.

Results of a consumer survey conducted for The Food Marketing Institute (FMI) in February showed that shoppers have reduced the methods by which they had been saving money over the past four years. At FMI's annual convention in Dallas this week, the strong indication is that people are buying more on impulse, are doing less with leftovers, planning fewer menus ahead and are purchasing convenience foods in record numbers.

But an offical of FMI, the association of the retail and wholesale food industry, said, "I am concerned beacuse all of these figures are now out of date. We don't know if shoppers will go back to their old habits now that food prices are rising so fast again."

The cost factor is ignored because convenience foods do cost more than those prepared at home. But at the rate food prices have climbed so far this year, the cost factor may become the deciding factor if people start slashing their food budgets as they did five years ago. In that period, food prices rose nearly 14 percent annually. At the rate they are going now, the annual rate could reach well over 15 percent this year.

Shoppers' reactions to spiraling food costs in 1973 and '74 were to cut back rather drastically on the convenience foods they purchased. When the food price spiral slow down, many went back to convenience products. THey may be forced to revert to their old habits once again.

Another theme that runs through a lot of advertising for convenience foods is the not so subtle suggestion that you can't cook as well as the food technologist who created the commercial product. Reading a list of often unpronounceable ingredients on the package, a cook may be convinced she could never put anything together like that. After all, who keeps carboxy-methylcellulose or calcium proprionate next to the curry powder in the cupboard?

Yet food made at home don't need these emulsifiers, antioxidants, stabilizers, artificial colors and flavors. Home-cooked foods don't have to last for two or three years. Natural ingredients don't have the problems of stabilization and emulsifying which are common to mixtures of chemicals. Top-quality ingredients don't require artifical color and flavoring to look and taste good.

The time-saving aspects of convenience foods are not quite so simple to sort out. Some foods, such as instant rice in a boil-in-the-bag package, take just as long to prepare as regular long grain rice. The meat, poultry and fish helpers save no time at all over making your own "helper." Not only does frozen orange breakfast drink take just as long to "prepare" as frozen orange juice, it's no cheaper.

But there is another group of people refusing to use convenience foods because saving time is not as important to them as the cost, safetly, nutrition and taste of the food they eat. Not that they would mind finding easier ways to do things. Almost everyone would!

And preparing your own mixes offers all of the qualities these cooks are looking for, along with convenience. It's just a matter of setting aside the time - at your convenience - to put the ingredients together. Then, just like the store-bought versions, they are ready when you are. And at half the price or less.

Making your own mixes has become such a popular way of cooking, a book devoted exclusively to such recipes has just been published.Some of the mixes in "Make-A-Mix Cookery" by Karine Eliason, Nevada Harward and Madeline Westover (H.P. Books, $4.95) are helpful, but some defeat their own purpose: They call for the use of commerically-made mixes in the home-made mixes!One for Russian Refresher Milk uses powdered orange drink mix and presweetened powdered lemonade mix. Four of the seven ingredients in Brown Beef Cube Mix are convenience foods: onion soup mix, cream of mushroom soup, cream of golden mushroom soup and cream of celery soup. The cover of the soft-cover book touts the recipes as being free of preservatives.Obviously that is not the case.

These recipes are the sixth set in an occasional series of do-it-yourself convenience foods which have run in The Washington Post food section over the last four years.

A cake mix free of artificial food colors and flavors, BTH and other advitives unnecessary in home preparation.

HOMEMADE CAKE MIX (14 cups of mix) 9 cups flour 1/3 cup baking powder 1/4 cup sugar 1 tablespoon salt 1 teaspoon cream of tartar 2 cups shortening

Sift the dry ingredients together. Cut in the shortening with pastry blender, two knives or fingers until it resembles cornmeal. Store in covered container at room temperature.

Three cups of mix make two eight-inch layers, or 2 dozen cupcakes

CHOCOLATE FROSTED CHOCOLATE CAKE 1 1/2 cups sugar 1/2 cup cocoa 3 cups cake mix 1 1/2 cups milk 2 eggs, slightly beaten 1 teaspoon vanilla

In a large mixing bowl combine the sugar, cocoa and cake mix. Beat in the milk, eggs and vanilla at medium speed for 3 minutes. Spread the batter in two greased and floured eight-inch round pans. Bake at 375 degrees for 25 to 30 minutes. Cool in pans for 10 minutes; turn out on cake racks and cool completely before frosting.

To make cupcakes, fill greased cup-cake tins 2/3 full and bake at 375 degrees for 20 to 25 minutes.

CHOCOLATE FROSTING (2 cups frosting) 3 squares unsweetened cholcolate 3 ounces cream cheese, softened 1/4 cup milk 4 cups confectioner's sugar 1/2 teaspoon salt

Melt chocolate in top of double boiler. Combine cream cheese with milk and gradually add sugar and salt. Stir in melted chocolate and beat until smooth. Enough to frost an eight-inch layer cake.

CHOCOLATE CHIP COOKIES (4 dozen) 3 cups cake mix 1 cup sugar 1/2 cup milk 1 egg, beaten 1 teaspoon vanilla 1 cup semi-sweet chocolate morsels 1/2 cup chopped pecans

Mix the cake mix with the sugar, stir in the milk, egg and vanilla and mix until well blended. Add nuts and morsels. Drop by teaspoonsful onto greased cookie sheets, leaving about 2 inches between cookies because they spread. Bake at 350 degrees for 12 to 15 minutes. Cool slightly, then remove from cookie sheets.

This is the basic white sauce from which cheese sauce can be made. It can be used as a binder or thickener as well as a sauce for vegetables and meats. Use any number of spices or herbs to change the tastes.

WHITE SAUCE MIX (Enough for 8 cups sauce) 1 cup butter or margarine 1 cup flour 2 cups instant nonfat milk 2 teaspoons salt, or less 1/4 teaspoon pepper

Cut the butter into the flour along with the other ingredients until mixture is crumbly. Refrigerate up to two months or place in the freezer for longer.

TO MAKE SAUCE: For medium white sauce, combine 1/2 cup sauce mix with 1 cup water in a saucepan. Cooke over low heat until mixture is smooth, stirring. Season with herbs and/or spices. To make a cheese sauce, add 1/2 to 1 cup cheese to thickened sauce and stir until cheese melts.

Like commerically prepared granolas, this recipe can be used in granola cookies and bars.

GRANOLA (10 cups) 3 cups rolled oats 1 1/2 cups wheat germ 1/2 cup dry skim milk powder 1 cup roasted, unsalted peanuts, chopped 1/2 cup sesame seeds 1 cup hulled sunflower seeds 1/2 cup vegetable oil 1/4 to 1/2 cup honey 1 1/2 cups raisins

Toast the oats in a shallow pan at 300 degrees for 15 minutes. In a large bowl combine the wheat germ, skin milk powder, peanuts, sesame and sunflower seeds. heat oil and honey just until warm. Combine with mixture in bowl. Combine contents of bowl with toasted oats and spread in several shallow pans in thin layer. Continue toasting, stirring occasionally, for 15 minutes more, or until ingredients are toasted. Spoon into large container; add raisins. Cool and store in tightly-covered container in refrigerator. Serve with milk.

The difference between this fruit gelatin and those that come in the packages is that these contain fruit juice, the color of the gelatin is the pale, subtle color of the juice.

FRUIT GELATINS (4 servings) 1 tablespoon unflavored gelatin 1/4 cup cold water 3/4 cup boiling water 1 cup fruit juice* sugar 1/4 teaspoon salt

Soak the gelatin in the cold water to soften. Dissolve in boiling water, stirring. Add 1 cup of the following fruit juices: orange, apricot, grapefruit, cranberry, grape, canned or cooked pineapple, peach, etc. Stir in salt. If not sweet enough, add sugar to taste. Chill until firm in mold which has been rinsed in cold water.

If desired, diced fruit may be added after gelatin has become consistency of unbeaten egg whites.

*Sherry and other wines can be used of some or all of the fruit juice. Strong coffee can be substituted entirely to make coffee-flavored gelatin.

One of the most popular dips is made with sour cream and a package of onion soup mix. This homemade version has neither the color or thickness of the dip made with the commercially-prepared product because it does not contain artificial color, potato starch, potato flour, cornstarch, a few of the ingredients found in the store-bought version.

ONION SOUP MIX 2 tablespoons plus 2 teaspoons instant minced onion 2 beef bouillon cubes, crushed

Combine onion and pulverized bouillion cubes. Use to make onion soup dip mix or to flavor rice.

ONION SOUP DIP MIX: Combine 2 cups of sour cream or half sour cream and half yogurt with mix. Mix well and add salt if needed. Refrigerate until serving time.

ONION-FLAVORED RICE MIX: Combine the onion soup mix with 2 cups of raw rice. Place in tightly-covered container and store in cool dry place. To serve, combine 1 1/4 cups of rice mix with 2 cups cold water. Bring to boil; cover, reduce heat and cook 15 to 20 minutes, until liquid is absorbed and rice is dry. Serves 4 or 5.

An inexpensive version of the French herb-seasoned triple cream.

HERB CHEESE 2 large cloves garlic, mashed 8 ounces cream cheese, softened 4 ounces farmer cheese 1/2 cup finely minced chives 1/2 cup finely minced parsley Salt and freshly-ground black pepper to taste

Add garlic, chives and parsley to cheese. Beat well. Season with a little salt and a lot of pepper.