If some of the meat in supermarkets is looking rosier than it used to, the reason is that a growing number of markets are selling it in airtight packages treated with a touch of carbon monoxide to help the product stay red for weeks.
Both of these steaks were red when bought on Feb. 3. Kept refrigerated, they were then photographed on Feb. 16. Why the difference? The one at top was treated with a process that has some consumer groups angered.
This form of "modified atmosphere packaging," a technique in which other gases replace oxygen, has become more widely used as supermarkets eliminate their butchers and buy precut, "case-ready" meat from processing plants.
The reason for its popularity in the industry is clear. One study, conducted at Oklahoma State University for the Cattlemen's Beef Board in 2003, said retailers lost at least $1 billion a year as meat turned brown from exposure to oxygen, because, though it might still be fairly fresh and perfectly safe, consumers simply judged meat's freshness by its color.
The carbon monoxide is itself harmless at the levels being used in the treated packaging. But opponents say that the process, which is also used to keep tuna rosy, allows stores to sell meat that is no longer fresh, and that consumers would not know until they opened the package at home and smelled it. Labels do not note whether meat has been laced with carbon monoxide.
The Food and Drug Administration approved use of the process in 2004. The Washington Post reported in its Monday editions that Kalsec, a Michigan producer of a natural food extract that helps slow the discoloring of the meat but does not "fix" it in the same way as carbon monoxide, had petitioned the agency to reverse that decision.
The Consumer Federation of America and the advocacy group Safe Tables Our Priority have written a letter to the agency in support of the petition because, they say, the bright red color could mask spoilage and dangerous bacteria in older meat or meat that has not been kept at the proper temperature.
Supermarket chains including A.&P. and Pathmark do not carry the treated meat, but it is showing up with increasing frequency elsewhere. In New York City, it is sold at 30 Gristede's stores, at D'Agostino markets under the labels Laura's Lean Beef and Creekstone's, and at the Morton Williams stores in the Associated chain. A spokeswoman for Safeway did not respond to phone calls and e-mail messages about sale of the treated meat there, but it was available at a Safeway market in Bethesda, Md., earlier this month. SuperTarget stores are also selling it, and Wal-Mart reports carrying it in 150 stores.
"This is what is going to happen in the meat business," said John A. Catsimatidis, chairman and chief executive of Gristede's. "The meat looks great. It looks as red as the day it was cut."
Processors say treated ground meat can be sold for 28 days after leaving the plant, and solid cuts for 35 days. The agribusiness company Cargill says it has sold 100 million packages in the last year.
Randy Huffman of the American Meat Institute Foundation, an industry group, said, "The primary benefit in providing this product to consumers is the red color they have grown to expect."
In a firsthand look at the treated meat, a package of a conventionally wrapped rib steak and one with the carbon monoxide were both red when bought on Feb. 3 near Washington. They were then kept refrigerated. By Feb. 16, when they were photographed for the pictures that appear with this article, the conventional meat was brown, but the treated meat was still rosy. And as of yesterday, other treated meat bought at the same time was still red despite having been left unrefrigerated on a kitchen counter since Feb. 14.
Some food scientists who approve of other forms of modified atmosphere packaging as a way of extending a product's life say this form of it can be unsafe. Michael Doyle, director of the Center for Food Safety at the University of Georgia, says one study found that when meat in modified packages that included carbon monoxide was stored at 10 degrees above the proper temperature, salmonella grew more easily.
Representative John D. Dingell of Michigan, the ranking Democrat on the House Energy and Commerce Committee, has asked the F.D.A. to explain its approval of the process.
"It's just common sense that when consumers buy meat, they use color as an important indicator of its freshness," Mr. Dingell said in an e-mail message to a reporter. "For F.D.A. to rely on a promise of some stamp on the package that says 'use or freeze by' is just naïve."
