The Japanese eat a lot of rice, but they love noodles, including the quick-cooking flavored ramen noodles first introduced in that country in the 1950s. Six years ago the Japanese opened that American market and now the noodles are threatening to replace TV sets as Japan's hottest export to this country.

In just six years the Oriental noodle market has gone from zero to a $200 million a year industry, much of it still produced by Japanese-American companies. Analysts say only the surface has been scratched.

According to Advertising Age. "What started as a simple instant noodle dish with mild spice flavoring has grown and branched out so rapidly that marketers are no longer quite sure how to identify the competition. Is it limited to other add-hot-water-and-eat items: Or is it everthing in the soup aisle?"

Is it soup? Is it lunch?" Will it save the supermarket from incursions being made by fast-food restaurants? Is it "the wave of the future?" Or perhaps more importantly, is it worth eating?

When the noodles were first introduced to the American market by Nissin they came in what are known as "pillow" packs. Those packages were - and still are - advertised as soup, main or side dishes. For them you need a pot filled with boiling water and the usual equipment necessary to cook noodles. Then a further refinement was added: a disposable container in which to cook and eat the product. All the in-a-hurry eater had to do was find a source of boiling water, a disposable spoon and wait three to five minutes for the noodles to soften. It might even be possible to dispense with an eating implement and simply "slurp" the contents of the cup.

It wasn't long before major American food companies - Lipton. Nestle and La Choy - were looking longingly at the market. They introduced products which, like the original pillow packs, require a serving dish. Most are single-serving items such as Lipton's Cup-a-Soup and Lite-Lunch, the basis of which is noodles. Nestle's sells its instant soup version as part of the "Souptime" line. La Choy's Iramen noodles "pillow" package serves two.

What is it that these dehydrated foods have to offer in addition to speed of preparation?

Noodles. With the exception of the instant soups, each of the packages is about 99 percent noodles, 1 percent seasoning. Even on the product where vegetables and meat are listed as ingredients, they never amount to more than a sprinkling. Often the meat is not visible to the naked eye. Some packages show bowls of noodles with slices of meat and vegetables, but in small print the purchaser is advised that what is pictured is simply a "serving suggestion!" This means if you want the meat and vegetables, you add them yourself.

In addition to the noodles, a few peas and carrots, several pieces of meat or scrambled egg - all dehydrated - many of these quick noodle meals and soups contain large quantities of sodium, some more than 1,000 milligrams per serving. So much that anyone on a sodium-restricted diet would not be able to eat most of these products. Most of them also contain sugar in some form - dextrose, corn syrup solids - even though sugar is seldom a constituent of soup.

With few exceptions the products contain chemical additives. Most of these additives are believed to be perfectly safe: some are known to cause allergic reactions in small but significant portion of the population; the safety of a few has been questioned.

Among the worrisome additives used is BHT (Butylated Hydroxytoluenel), which in 1976 the Food and Drug Administration proposed removing from the list of Generally Recognized As Safe (GRAS) additives until furthur studies could be done. It is found in La Choy ramen noodles!

Some of the products contain artificial colors, all of which are under suspicion because they have been poorly tested. Some or all of the flavors of the following products are artificially colored with caramel coloring: Lipton's Lite-Lunch varieties; Maruchan's Ramen Supremen Noodles and Instant Lunch in a Cup, Nissin Foods' Oodles of Noodles and Betty Crocker's Mug-O-Lunch. Caramel coloring is on FDA's priority list for testing.

Most of the products contain monosodium glutamate (MSG) to which some people are allergic. Only Suddenly Spaghetti and Spaghetti To Go, both products of Sanwa Foods, do not list MSG on their labels. Though Sanwa's Noodles To Go trumpets "No Preservatives," MSG is an ingredient. It is helpful when reading labels to understand the distinction. "No preservatives" is not the same thing as "no additives.")

In addition to those discussed Lipton Cup-a-Soup and Nestle's Souptime were also included in the survey. Here are some observations:

Lipton's Lite-Luch a la king flavor contained the equivalent of one pea. The chicken flavor contained two recognizable pieces of chicked, 12 slices of carrot which ranged in size from 1/16 of an inch square to less. The Oriental style contained 3 pieces of red pepper about the same size.

Noodles To Go offers a shrimp version. It contains six shrimp, each 1/2 inch long or less; 5 1/2 green peas, eight thin slices of carrots, each 1/16 of an inch square or less and 4 pieces of scrambled egg, approximately the size two peas.

Oodles of Noodles shows a "suggested srving" with 2 slices of chicken and two slices of chicked and two slices of carrot. The list of ingredients includes dehydrated chicken meat. None was visible to the naked eye in the package sampled. Nor was there visible pork in the pork flavor package.

Nestle's Souptime mushroom soup lists "mushroom" (singular) in its ingredients. The scraps of mushrooms visible were not enough to make up one complete mushroom.

Suddenly spaghetti, meatless with Italian-style sauce mix, contains tomato powder, beet powder, paprika and tomato flavor to beef up the color and the flavor of the tomato powder. It also contains imitation Romano cheese.

La Choy's label for Oriental noodles with beef flavoring shows a bowl of noodles with three strips of meat, several carrots some green vegetable. To the side are additional slices of meat and snow peas. There is no beef or natural beef flavoring in any form in the package. The primary seasoning ingredient is salt; the second ingredients is MSG.

The primary seasoning both chicken and pork flavor Maruchan Ramen Supreme Noodles is also salt.

Lipton's Cup A Soup-chicken noodles with white meat chicken contained six cubes of chicken, each about 1/4 inch square, plus 15 thin shreds.

Betty Crocker's Mug-O-Lunch, artificial beef flavor, noodles and gravy mix, pictures noodles mixed with what appear to be pieces of beef, but the only form in which beef is present in the product is as "beef fat." The "beef" pieces are actually hydrolized vegetable protein.

When an informal taste test was conducted among five people, comments ranged from: "the meat tasted like cardboard," and "the noodles are likea wet bathing suit," to one person's opinion that the noodles were "fantastic" because all you have to do "is add water and they swell up."

On the whole, the pillow packages of noodles fared better than the individuals servings. "That's because," one taster said, "you add good things to them." Which, of course, you can do with any packaged noodles for considerable less money.

A single serving of these products ranges in price from about 15 cents for the soup without noodles to 69 cents for the noodles in cups. That means that in addition to being quick they are not expensive. But then, noodles and spaghetti are cheap. Are they a good nutritional value?

It's hard to know becuase, with the exception fo the Mug-O-Lunch and the Lite-Lunch, they do not have nutrition labeling. Those two products have some protein and thiamin, with small amounts of a few other vitamins. But because they are highly processed foods, nutritionists explain, many essential nutrients may be missing. The more processing raw ingredients undergo, the greater their loss of nutrients, especially the micro-nutrients which are found in natural foods in trace amounts and which the body needs in minute quantities.

Some of the packages suggest these products as "an instant meal," "instant hot lunch," or "the newest is lunch-time ideas." According to Dr. Carole Christopher, a nutrition consultant at the Federal Trade Commission: "None of these foods is as appropriate for any meal because they have been pretty well stripped of their nutrients.