High Pressure Keeps Food Fresh, Fans Say

March 27, 2005|By Frank Greve, Knight Ridder Newspapers

WASHINGTON -- Some food-industry Ph.D.s sound as if they've been smoking something other than salmon.

They talk of orange juice that, after 12 weeks of refrigeration, tastes as good as fresh, of TV dinners that "deliver a gourmet restaurant experience," of bananas that don't turn black and of scrambled eggs for soldiers' rations that taste as if they were just cooked.

The secret, they think, is a costly new high-pressure preservation technology. Only a few U.S. food processors use it, but Martin Cole, the director of the National Center for Food Safety and Technology at the Illinois Institute of Technology in Summit, Ill., predicts that high-pressure preservation will be "the biggest thing in food processing since commercial canning."

Part of the argument for high pressure is that, when it's used on fruits, "flavors and vitamins are not degraded," Cole said.

Tom Mertensotto, marketing director for Perdue Farms' ready-to-eat products, seconds the claim. High pressure, which Perdue uses for its Short Cuts grilled chicken and grilled turkey, "does not change the texture, taste or nutritional values of our products," he said.

The process, which uses pressure equal to the weight of two elephants standing on a dime, takes about 10 minutes. Vacuum-packaged food is dunked in tanks of water, the tanks are sealed, then more water is pumped in. As the water pressure rises, compressing the food, it kills bacteria, enzymes and molds by breaking their molecular structures and popping their cell walls like blisters. Once the pressure's off, the food returns to its original volume and appearance.

Why isn't the food pulverized? As long as pressure is uniform on all surfaces of an object, it won't distort it.

The process might enhance taste. In a blind tasting of deli meats, grilled chicken and guacamole preserved by high pressure and by chemical additives, 22 tasters assembled by Knight Ridder generally preferred foods treated the new way.

Even a cold-cut pro -- Steven Loeb, meat buyer for Loeb's Deli, a Washington fixture since 1959 -- was mildly impressed. "This turkey tastes like turkey," he said. "Some doesn't, but this does."

High-pressure preservation has its down side, though. It's too expensive for many products and still requires refrigeration. It doesn't work well on vegetables and discolors foods if the pressure is too high.

For all these reasons, processors tend to use the process on foods with high markups, such as deli meats, oysters and convenience products.

High pressure has a lot of advantages, though.

First, it offers better protection than chemical additives from food-borne illnesses such as salmonella and listeria, which, according to the federal Centers for Disease Control and Prevention in Atlanta, kill about 5,000 Americans a year. That helped it win U.S. Department of Agriculture approval.

Second, high-pressure preservation eliminates the need for chemical preservatives.

A third advantage appeals both to the USDA and to the food industry: High-pressure preservation extends shelf life. This could mean new and expanded markets for U.S. producers.

Take Don Bowden, 72, of Keller, Texas, the president of Avomex Inc.

Bowden owned a string of Tex-Mex restaurants in Texas in the '80s and made his guacamole in Sabinas, Mexico. If the guacamole was trucked into Texas fast he could distribute it almost statewide. A better preservative, he thought, could expand his market dramatically.

So he and 30 pounds of avocado flew to Columbus, Ohio, in 1989 to visit Autoclave Engineering, which made machines that sterilized doctors' implements by pressure-cooking them. Autoclave had improved pumps and stronger water tanks.

Working without heat, technicians produced pressure of 80,000 pounds per square inch and avocado pulp that, if vacuum-packed and refrigerated, tasted fresh for 30 days. It's now sold nationwide as AvoClassic guacamole.

So how does Bowden's AvoClassic guacamole taste?

"It tastes like it's fresh," Bowden said. "But then we never had any ugly children in my family, so you'd better ask someone else."

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