Daniel Marsula, Post-Gazette

If the meat you buy at your neighborhood grocery store is bright pink, it must be fresh, right? Not necessarily.

Since 2002, the Food and Drug Administration has allowed the meat industry to sell various types of meat treated with carbon monoxide, which preserves the meat's pink color long after it normally would have turned brown without actually spoiling.

Keeping it pink allows grocery stores to sell meat they otherwise might have thrown away, but it's not to everyone's liking. Some lawmakers, meat industry observers and even some local grocers aren't so sure it's a good idea for consumers.

Ed Steinmetz, vice president of meat, seafood and prepared foods for Giant Eagle grocery stores, said consumers who aren't paying careful attention to expiration dates or who, in their thrift, are inclined to use meat past those dates, might well be misled by the carbon monoxide-treated meat's fresh-looking color into buying and even eating spoiled meat.

"One of the concerns about that technology is that beef and fresh cuts of meat, as they age, they'll show visual signs of aging. But with that technology, those signs of aging are less apparent," Mr. Steinmetz said.

The FDA has long banned the addition of food colorings, or color additives, to fresh meat because consumers might be deceived into thinking the meat is fresher than it is. On the other hand, it has allowed the addition and application of substances such as citric acid, ascorbic acid and rosemary extract to delay the natural browning process as meat ages.

The FDA, under a fast-track approval process begun in January 2000, found that past federal rulings held that carbon monoxide is not a color additive, but rather "fixes" the red color normally found in freshly packaged meat. And, in response to requests by companies, including meat-packing giants Cargill Meat Solutions Corp., Hormel Foods Corp. and Tyson Foods Inc., the agency began allowing companies to treat fresh ground and whole muscle cuts of meat such as steaks and roasts with carbon monoxide beginning in 2002.

While color change and spoilage are linked in the minds of most people because they tend to occur at the same time, color is not necessarily a good indicator of spoilage, according to George Pauli, associate director of the FDA's Office of Food Additive Safety.

"You can't see microorganisms," Mr. Pauli said. "Color is a chemical change that has nothing to do with bacteria. They're really independent processes."

Researchers for the beef industry have found that the industry could recover as much as $1 billion a year in discarded meat if beef on retail shelves was kept a desirable-looking color just a day or two longer than usual, according to the National Meat Institute. Treatment with carbon monoxide can keep the meat pink for weeks longer than usual.

Nationwide, about 10 percent of so-called "case ready" meat packaged at a central meat-packing plant and then shipped to grocery stores now is treated with carbon monoxide, the trade group has found. About a quarter of all beef and half the ground beef now sold is "case ready," according to the group.

During the treatment, which occurs at the packing plant, ground or whole meat is placed in a high-sided styrofoam tray and covered with a thick plastic film that allows the atmosphere inside the package to surround the top and sides of the meat. In some, but not all, cases, carbon monoxide is used to displace the oxygen in the package.

Once in contact with the meat, the carbon monoxide reacts with the natural myoglobin in meat, the substance that usually carries oxygen into the muscle tissues, to produce carboxymyoglobin, a bright red substance that resists turning brown. Normally, oxygen reacts with myoglobin to create oxymyoglobin, which tends to turn brown over time.

Research submitted by the meat industry, federal food regulators said, showed that other than a delay in browning, there was no difference between treated and untreated meat that might endanger consumers.

The data showed that carbon monoxide-treated meat contained no more bacteria than untreated meat, still gave off a foul odor and gases when it spoiled, and turned brown by the end of its shelf life, said Robert C. Post, director of the Labeling and Consumer Protection staff at the U.S. Department of Agriculture.

When buying meat, he said, consumers should base their decisions on how much time is left before the package expires -- 28 days after packaging for ground meat and 35 days for whole cuts -- not on its color.

"The critical thing is that they use the 'use by' or 'sell by' date," Mr. Post said. "We have been training consumers to know that's a critically important piece of information on which to base their purchase decisions."

Some lawmakers are questioning the practice, however, and a Michigan company has asked the FDA to ban the treatment, saying it can trick consumers into thinking they're buying meat that's fresher than it really is.

Don Berdahl, vice president and lab director of Kalamazoo-based Kalsec Inc., said Friday that a package of carbon monoxide-treated ground beef in his refrigerator which expired Nov. 26 is still a bright, wholesome-looking pink.

"It mimics the pigment. It stays bright red so the consumer can no longer use the color as a judge of freshness," said Mr. Berdahl, whose company makes natural food colorings that the federal government prohibits from use in fresh meat. "We think it's an unnecessary risk."

Opening that long-expired package would release a rotten smell, he said. But if the meat was less spoiled, some consumers might not get such an obvious warning sign, and others wouldn't discover a problem until they had bought the meat and opened it at home, Mr. Berdahl said.

In one experiment, he said, untreated meat left overnight at room temperature had turned brown and started to stink by the next morning. Treated meat left out at room temperature stayed bright red for five days, then started to leak and stink, Mr. Berdahl said.

The FDA has not ruled on Mr. Berdahl's request, which he made Nov. 15. On Feb. 9, U.S. Reps. John D. Dingell and Bart Stupak, both Michigan Democrats and members of the House Committee on Energy and Commerce, questioned the FDA's decision to allow carbon monoxide-treated meat and asked the agency to respond by Thursday to its concerns about whether the process is safe for consumers. The European Union banned the practice in June 2003.

Meat industry representatives, however, said treated meat is safe. It makes sense to allow meat that has not expired to look as fresh as possible, said Janet Riley, senior vice president of public affairs for the American Meat Institute, the nation's largest meat and poultry trade association.

"Color is just one factor in freshness," she said. "What this does is help meat stay red throughout its shelf life. It maintains the appeal. If you slice an apple and it becomes brown, it becomes less appealing to the consumer, but that doesn't mean it's less safe."

Carbon monoxide-treated meat has had mixed success with consumers at some stores that have tried it. A spokeswoman for Wal-Mart, which increasingly is using "case-ready" meat in the special packaging, said the company tried marketing monoxide-treated meat at about 100 stores in Missouri and Arkansas. It has dropped the products because of a lack of consumer demand, she said.

At Giant Eagle, the only carbon monoxide-treated product is a pre-made hamburger which is produced and packaged under the Giant Eagle brand name by Pennsylvania-based Taylor Packing, a division of Cargill, according to Mr. Steinmetz. The burgers are shipped to Giant Eagle's smaller stores, which don't employ enough people to make burgers at the store, as is done at the larger Giant Eagle stores, he said.

Those stores have been ordering pre-made burgers from Taylor for two or three years, Mr. Steinmetz said. Taylor began treating the burgers with carbon monoxide about a year ago, he said.

For now, the "jury is still out" on whether carbon monoxide-treated meat shipped from a central warehouse will become widely accepted, he said. Giant Eagle doesn't plan to expand the number of carbon monoxide-treated products at its stores, according to Mr. Steinmetz.

"We've basically committed to producing products fresh for our customers at the store," he said. "That's really the direction we're committed to right now because of the freshness aspect and because customers tell us they enjoy the service we provide."

Some stores don't know what, if any, meat they sell has been treated. A spokeswoman for Supervalu, the owner of Pittsburgh's Shop 'n Save grocery stores, said some of her company's meat products are in the kind of packaging that can include carbon monoxide, but she didn't know if the meat is treated with carbon monoxide.

Because the FDA does not require meat treated with carbon monoxide to be labeled as such, there's no way for consumers to know if the meat they're buying is pink because it was just packaged or because it was treated with carbon monoxide, Mr. Berdahl said.

"That's the problem. You cannot tell definitely that it hasn't been treated," he said.