THE Eastern seaboard's first commercially available, shelf-stable milk is expected to appear on shelves in major Baltimore-Washington supermarkets early this month. Until now, it has been available in Florida, Georgia and the Carolinas and through another packager in Washington State, California and Alaska. The product has been widely available in Europe for two decades because of less stringent government regulations.

Shelf-stable means that the milk can sit unopened in the cupboard for up to three months, and with luck, 15 to 21 days opened in the refrigerator.

For consumers it means convenience, alternatives and higher prices.

For Dairymen Inc., the cooperative that is producing the half-pint and quart containers of multi-flavored milks, it means a revolution in marketing by which it hopes to entice enough new milk drinkers to keep dairy farmers in the black and excess milk out of government warehouses.

On the shelves, the milk will be sold as Farm Best and Sip Ups. In marketing lingo, however, the milk has been dubbed generically as UHT--an acronymn derived from its ultra-high temperature processing. Flash heating (to 280 degrees) and cooling (to 70 degrees) and high-tech packaging procedures keep the milk from spoiling at room temperature over time by destroying all spoilage organisms and spores and removing the air so that none can grow. By contrast, pasteurizing temperatures of 161 degrees for 15 seconds kill pathogenic organisms but not spoilage organisms, so conventional milk requires refrigeration. Refrigerating UHT milk will extend its shelf-life, although a spokesman for Dairymen says that the flavor is "not guaranteed" beyond the pull date marked on the top of the package.

Consumers likely to benefit from shelf-stable convenience are those who don't like making special trips to the grocery for extra milk, those who drink milk infrequently and people who don't love returning from a few days out of town to a carton of sour milk.

Distributors, wholesalers and retailers besieged by rising energy costs will benefit from UHT milk, which obviously requires no refrigeration for shipping or storage.

This doesn't mean it should be drunk right off the shelf, because it would taste like warm milk. "Like any other beverage," says Lawrence Johnson, vice president of Dairymen, "you're going to drink it cold." He says consumers should think of UHT milk "just the same as if they bought mayonnaise or a six-pack of beer." They'd probably want it chilled before drinking it, but until then, they can save refrigerator space.

As a member of an industry plagued by bad publicity concerning overproduction at taxpayer expense, Dairymen hopes UHT milk will reach or regain an entirely new patronage for liquid milk. "We hope we don't have to sell milk to the government," says Johnson. Cautious not to create competition within the co-op, however, he says "this product is not intended to take away from other milk sales."

Other milk sales occur primarily by gallon container, in which about 60 percent of fresh milk is sold. Technology limits the size of UHT milk containers to quarts or smaller; bigger packages don't hold the seal. But this size reaches a consumer who doesn't traditionally buy milk, thus creating new milk drinkers, says Johnson.

In addition to lowfat and whole white, some UHT milk is flavored with chocolate, banana, fruit punch and vanilla and packed in half-pint containers with straw attached. These are designed to entice consumers away from other snack drinks. Promotion in the early markets for the product includes pejorative reference to other canned and bottled fruit-flavored drinks, with which shelf-stable milk will compete for shelf space.

The ad refers to the fruit drink competition by saying "10 percent fruit juice means 90 percent what?" and begs questions about the nutritional profile of the flavored milk, which lists "corn sweetener" second in the ingredient labeling and packs a heavy 170 to 180 calories per eight-ounce serving.

The sweet flavors mask the one anomaly in the taste of UHT milk--during ultra high heating one of the proteins changes shape and causes the milk to taste richer, so that UHT 2 percent milk tastes a little sweeter and has a little more body than its fresh counterpart.

All this high-tech processing results in a 30 percent higher prices at the grocery store.

Part of the reason is the five-layer rectangular milk box that includes three layers of plastic, one of aluminum and one of paper and costs twice as much as the conventional reinforced paperboard milk containers, according to Dr. Victor Jones, of North Carolina State University where UHT milk has been studied for the last 25 years.

But another reason, says Gary Smith of Real Fresh Inc., in California, is that retailers put the milk on grocery store shelves with the traditional 30 to 35 percent grocery mark-up rather than putting it in the dairy case with the usual 16 percent markup. "They haven't learned yet," he says of the retailers who sell his product in California, Washington State and Alaska.

In addition, the small market for this milk means prices won't benefit from mass distribution, but this could change if the product becomes more popular.

Dairymen Inc., which sunk $16 million into its Savannah, Ga., processing plant, has been creeping up the East Coast with this milk, in a systematic approach to introduce one community after another to the attributes of UHT.

"The plant was in Savannah," says Johnson, "so we started distribution near Savannah." After the milk's May 1 introduction at the World's Fair in Knoxville last year, it was released state by state in Georgia, Florida and the Carolinas. "From then until now, we finally got our act together," says Johnson, and the milk is ready for the Washington-Baltimore market crammed full of the small households, travellers and occasional milk drinkers to whom this milk is expected to appeal.