A&P, the nation's second largest food chain, has introduced a line of brandless or "no-frill" products in Washington that cost about 30 percent less than nationally advertised brands and 19 to 15 percent less than the chain's better quality house brands.

To Washingtonians, who pay more than most other Americans for their food, it is an opportunity to buy lower quality items in plain white wrappers with black lettering at considerable savings.

A&P, which has 48 stores in the metropolitan area, is following the lead of 20 or 30 other supermarket chains across the country that began selling "generic" items after Jewel Food Stores in Chicago started doing so 18 months ago. Jewel has been so successful with its unbranded products that it is now selling 100 different items.

A&P introduced its version of generics, "Economy Corner," in several Northeastern cities in April. The line of 14 products has been successful enough that the company enlarged its test markets yesterday to include Washington-Baltimore, Atlanta and Birmingham.

Now 250 of the 1,900 A&P stores are selling no-frills green beans, whole kernel and cream style corn, sweet peas, trash can liners, facial and bathroom tissues, paper towels, dog food, laundry and dishwashing detergents, liquid bleach, fabric softener and macaroni-and-cheese dinners.

According to the company, the most popular item is macaroni and cheese, which sells for 27 cents a box. A&P prices Kraft's macaroni and cheese at 34 cents and their Ann Page brand at 30 cents.

Kraft's has a sharper and more expensive cheese. It contains 3/8 ounce more cheese sauce mix and 3/8 ounce less macaroni than the no-frills box.

The no-brand vegetables are standard rather than fancy grade, which means they are mature and thus less tender than younger, higher quality produce. The pieces are uneven in size and shape; the color and texture vary.

Whole-kernel corn is about 15 cents cheaper than Del Monte; 8 cents less than Ann Page.

The June issue of Consumer Reports carries the results of testing of one chain's generics versus its house brands and nationally advertised brands. The magazine concludes that the taste of the generic products sometimes is better, sometimes worse and sometimes quite similar to the other products.

Nutritionally, the generics are the same as their more expensive counterparts and all of those sold at A&P carry nutrition labeling.

The paper products are lighter in weight and not as soft as the more expensive brands, and they are not perfumed. The soap products are not as strong. According to Dick Beazer, private label manager for the chain, the laundry detergent contains none of the additives of some national brands so it won't get clothes as white and will not work as well on heavy spots such as grease.

The toilet paper is not as soft and fluffy, the dish detergent will not wash as many dishes, the fabric softener is only half the strength of a leading national brand, Downy, but Baezer said: "It is so much cheaper that it still costs less to use." Two quarts of Downy sell for $2.19; 2 quarts of the no-frill brand are 59 cents.

The generic lines, which are really a new packaging version of an old concept, have not met with universal acclaim. While some industry observers describe them as "the hottest idea in years," others consider them "merchandising gimmicks" and "just a passing fad."

A&P and other chains have sold a few similar quality products as their cheapest house brand items in a few markets. A&P's version, called Marvel, has never met with much success.

The company hopes the increased interest among consumers in lower cost food and the trend to no-frills in the industry, coupled with repackaging and a new name, will bring them the success it has brought other chains. They hope to add another 25 items soon.

But those who think the idea is just a gimmick say that when a number of retailers carry generics they will lose their competitive advantage; that eventually there will not be sufficient quantities of standard grade fruits and vegetables, so prices will rise and generics will become less economical. They also say most consumers will opt for quality and uniformity in the long run."

But Kathleen Sheekey, information director of the Consumer Federation of America, thinks it's a good idea. She told an industry trade journal: "For those who can afford to pay a few extra pennies for esthetics, fine. But consumers should have a choice and pay less if they don't care about extra plumpness and color."

The no-frills idea first popped up in France two years ago, where it is called produits libres, products free of advertising. This is a reference to the fact that there is little or no advertising besides the initial announcements of the product line.

Lack of advertising and the plain wrapping contribute only about one percent to the savings, according to A&P. The biggest savings are in the products themselves.

A&P generics will not have the Washington area to themselves much longer. Sometime this summer the nation's largest supermarket chain, Safeway will introduce its version of no frills. Giant, which shares more than 50 per cent of the Washington market with Safeway, says it has no plans now to sell generics.