What began as a beauty pageant ended up in a full-fledged rugby scrum in a tasting of a dozen domestic and imported white jug wines sponsored by The Washington Post.

Six wines from each category had survived earlier tastings and earned the the right to be included in the finale.

When the swirling, sniffing and sipping was done, only 2 points on a scale of 20 separated the first-ranked wine from the last. The surprise winner was Italian Swiss Colony's Chablis. But so narrow was the margin, and so diverse were the opinions of the tasters, that the real result of the competition was a confirmation of the high caliber and diversity of jug wines on the market today.

The manufacture of jug wines -- at least the better ones -- is so carefully controlled that there is little to choose among them in color or appearance. Most are straw-gold and clear. Bottle shapes differ, but sizes have been standardized. Whether they have corks or screw tops is immaterial because these wines should be drunk soon after purchase. Don't plan to store them in hopes the quality will improve.

The differences are to be found in the glass, particularly in smell and in the balance between sugar and acid. None of these jug wines is a varietal. The consumer is not told what grapes have been used, nor should one expect to find strong varietal characteristics in the smell or taste. But you will find some of them too tart, or too sweet, for your own taste.

For example, if categories were drawn from the final tasting, they would shape up like this:

Distinctly dry wines: Los Hermanos Chablis, La Fleur Blanche, Alexis Lichine White Table Wine and Villa Banfi Roman White.

Wines touched with sweetness: Taylor California Cellars Chablis, Ecu Royal French Country White, Paul Masson Chablis.

Neutral wines: Italian Swiss Colony Chablis, Inglenook Navalle Chablis, Fetzer Premium White, Remy Pannier Blanc de France, Bon Frere Blanc.

Before you shudder at the sound of "sweetness," remember that most of the great German wines are somewhat sweet and that grape sugar, if balanced by acid, can be very pleasing indeed. Furthermore, the tartness of very dry wines can make them unpleasant to some wine drinkers. Therefore, the proper approach is to sample several to find the degree of sweetness or dryness that is pleasing to you.

Keep in mind as well what your intentions are toward the wine. Will it be drunk alone as an aperitif, or served with food? What food? (There is a tradition of serving dry white wine with shellfish. It is not a hard and fast rule, but it is a good tradition. Conversely, too dry a white wine might clash with a chicken or fried fish dish.)

In making wines for a mass market, there is a natural desire to avoid offending the consumer. Jug wines do not have larger than life personalities. How often, in fact, have you been impressed enough with a carafe wine in a restaurant to ask what brand it is? (You may well have been unhappy enough to demand to know, but that is another story.) The range of the scores in the tasting, from 11 to 13 points, indicates decent but not distinguished wine. Italian Swiss Colony's chablis compiled the winning total because it was the only one to receive at least 10 points from every taster. Only one panel member chose it first and one other had it tied for first, but it offended no one and thereby backed into the winner's circle.

Of course, Colony's chablis is attractively priced and, with so many other factors being either equal or offsetting, price surely should play a part in purchase decisions.

Incidently, the panel at the blind tasting mistook the origin -- domestic or foreign -- of only two wines. A majority voted Los Hermanos and Fetzer Premium White to be imports before their identities were revealed.

Under the system used, the wines were sampled from identical carafes, each bearing only a letter symbol. Scoring was completed before the letters were matched with brand names.

There were some relatively dramatic shifts in position from the two earlier tastings. Paul Masson, the domestic winner, and Ecu Royal, which took first place at the imported wine tasting, failed to repeat their successes. Fetzer Premium White fell from second in the domestic tasting to twelfth in the final; La Fleur Blanche climbed to a tie for second after finishing sixth among the imports.

How are these changes explained?

First, although they bore the same labels, the wines themselves could be somewhat different if they were made at different times and arrived here in separate shipments. Also, the wines were purchased at a different retail store than those used in the earlier tastings. Time on the shelf and storage conditions could play a part. (In all wine tastings, we use bottles purchased from retail outlets rather than soliciting samples from manufacturers or distributors.)

These bottles were freshly opened. But consumers who buy 1.5-or 3-liter jugs should realize that while the wines have been highly processed to remove bacteria, contact with the air will cause them to deteriorate. Don't expect jug wine to taste the same after a few days in the refrigerator.

Four of the 13 tasters had not participated in either of the first two tastings. They brought with them their own perceptions. Also, with the less successful bottles on the sidelines, comparisons became more difficult.

Complaints of a smell of sulphur appeared to be at least partly responsible for the poorer showing in this competition of Fetzer and Ecu Royal. Sulphur is widely -- and legally -- used to stabilize white wines. But if its use is not carefully controlled, an unpleasant smell remains with the wine.

Detailed results of the tasting appear on Page E10.

In answer to numerous requests, a similar series of tastings of red jug wines will be conducted as soon as tired palates revive, probably in March.