Reynolds Metals calls it a "Flex-Can," rival Continental Group prefers "Pantry Pack", and the generic name is "retortable pouch."

The retortable pouch is a new kind of food package, a cross between aluminum foil and plastic bags.

It is a shiny, flexible aluminum envelop laminated between two different kinds of plastic. The inside plastic is inert to protect the food. The outside plastic is tough to withstand heat. The aluminum foil is a barrier to air light and contaminants.

Like the "boil-in bag" that some frozen vegetables are packed in, the retortable pouch can be dropped into a pan of boiling water to heat the food for serving.

And like a conventional tin can, the pouch can be filled with food, sealed and processed under heat and pressure so the food will keep on the kitchen shelf without refrigeration.

Last month the first foods in pouches - chicken cacciatore, beef stew and five other entrees - went on sale in test markets in Fort Wayne, Ind., Syracuse, N.Y. and Fresno Calif.

And the Defense Personnel Supply Agency in Philadelpia recently met with suppliers to review specifications for 40 million pouches of combat rations from pork and beans to pineapple nutcake.

By 1979 a number of consumer food products will be on the supermarket shelves in pouches, predicts Continental.

Within five years, Americans will be using 220 million pouches a year, says Reynolds, which calls the new container "the most important packaging development since the tin can."

Continental, the nation's biggest can maker, is less ready to predict the pouch will replace the can. "I'd say it is one of the most important developments," said Richard Abbott, director of marketing for Continental's flexible packaging division.

The two packaging giants so far are the only American makers of retortable pouches. While they were developed independently, the two versions are so similar "you couldn't tell them apart," said a spokesman for one company.

Both makers agree that the first uses of the new package will be as an alternative to frozen foods rather than as a competitor for conventional cans.

Continental and Reynolds are both supplying packages for the pioneer pouch products now being test marketed. The single serving, one dish meals, selling in the 80 cents to $1 range, are produced by Continental Kitchens, a division of ITT Continental Baking, the makers of Wonder Bread and Morton frozen foods. (ITT Continental, the food company, and Continental Group, the package supplier, are not otherwise related).

50 sales figures have been made public, but both package suppliers say they have re-orders from Continental Kitchens.

Compared to packaging a frozen one-dish meal in an aluminum foil pan, the flexible laminated pouch costs about 10 per cent less, said Yale Brandt, marketing manager for Reynolds' version.

When the added costs of refrigerated shipping, warehousing and display cases are counted and the special freezer bag at the checkout is thrown in, the pouch pack has a 4 cent a package advantage over frozen foods, continental claims.

Both package makers say consuemr tests show the pouch-acked entrees are comparably rated against frozen foods in taste and better than canned versions.

Foods in flexible containers are processed in much the same way as conventionally canned foods. The sealed pouches go into steam-heated pressure vessels, called retorts, where the products are cooked in their container.

Because the flexible package conforms closely to the food inside, the cooking time at the packing plant is about 40 per cent less and the food tastes fresher, the package makers contend. Because they are fully cooked, the pouch packed foods can be eaten right from the container, or heated in boiling water in three to five minutes, compared to a half hour for frozen meals.

The next phase. Abbott predicted, will be "totally new products for a new package."

Abbott foresees new kinds of finger foods, processed in their package, or meals in pouches supplied by vending machines that automatically heat the package after the customer makes a selection.

Rather than heating pouches in a pan of boiling water, a new small appliance is being developed to quickly warm the bag Abbott said. A toaster could easily be modified for the job, he said, though there is a serious danger of shock if the aluminum-pouches were put into a reular toaster.