Seven years after Elmer Davies' death, his innovation may be about to catch on.

DASI Inc. of Chevy Chase is marketing a system for treating milk, other dairy products or juices so that unopened containers can be unrefrigerated for about three months and opened ones can be kept in the refrigerator for between one and two months.

Not having to refrigerate milk while distributing or storing it has enabled companies to sell milk in Germany for 20 percent less than pasteurized milk, for example, and similar savings can be expected in this country, according to DASI's president, John Nahra.

DASI's system destroys bacteria by heating liquids to between 150 and 300 degrees Fahrenheit in one-third second. Bacteria cause spoilage, necessitating refrigeration, which slows the process.

From 10 to 15 other ultra-high-temperature (UHT) systems are being used in Europe, but Nahra says that DASI has eliminated the cooked taste that has plagued UHT systems since their initial use after World War I.

According to Nahra, the first UHT systems sterilized milk in its final container, but the result was no better than milk sterilized at home in a pressure cooker--taste and nutrition were found wanting.

After World War I, products sterilized in the bottle or can began to take hold, however, partly because of the comparative lack of refrigeration.

Elmer S. Davies was in charge of a cheese plant in the 1920s and 1930s when he came up with the concept of sterilizing a liquid by quickly heating it in a free-falling-film. But no one was interested then, and "rightly so," Nahra relates. "He was way before his time"--the necessary sterile packaging had not been developed.

Davies went out on his own around 1940, and with his brother--an electrical engineer--worked on the process in a garage. They found that there was no way to radiate sufficient heat from a filament around which the milk fell, so in the late 1940s they turned to steam.

In the 1950s, he established Daveat Processing Co. (Davies' Heat) and found investors. The goal was a commercial prototype. Davies progressed from sending milk through a tube surrounded by steam to sending a film of milk falling over the plates that helped form the film to substituting screens for plates to reducing the length of the screens. Each step reduced burning and the resultant cooked taste.

But burned milk was collecting even on the abbreviated screens after the machine was operating for a while. That problem and the absence of asceptic packaging stymied them, and they ran out of money in the early 1960s.

Processes for quickly heating liquids outside their final container, improving their quality, began to enter the European market in the late 1960s.

Nothing more was done until 1970 when Nahra entered the scene. He had come to the United States in 1955 from Lebanon, had received an undergraduate degree in engineering science from Case Reserve, and then a masters degree and PH.D. in aeronautical and astronomical engineering from Purdue. Nahra then worked for TRW's systems division in California on mission analysis for the Apollo program, and for Bellcom, a D.C.-based subsidiary of AT&T, on the manned space program.

Then he followed a cousin's suggestion and contacted Jim Sands, whose father-in-law had invested in Davies' process. Sands asked him to look into the process.

Nahra left Bellcom to form DASI with Sands. They found investors, tested Davies' hypothesis and developed a working system with the University of Maryland under a program that since has ended. During that program, the burning was eliminated by removing the screens and forming the liquid film in other ways, and technology was developed for getting the milk out of the heater and into new sterile packaging.

A small Canadian dairy company bought DASI's first system in June 1981--and it is just getting into operation.

"We haven't earned any money" so far, Nahra notes. He believes that the only way the company can make money is by licensing others to make the system.

UHT milk is now available in the United States from Dairymen's Inc. under the Farmbest label, using European technology. It is priced about 10 cents a quart higher than normally processed milk now, but Nahra believes it eventually will cost less because distribution and storage advantages will more than offset higher processing costs.

"I don't think anybody has a clear view as to how the market will change," Nahra says. "Sometime downstream, pasteurized milk is going to be just like cream milk--you won't be able to buy it."