Carbon Monoxide Packaging of Fresh Meat

Recent media reports have raised concerns regarding the safety of fresh meat packaged with carbon monoxide. These reports have resulted from persistent efforts by private interests to garner public and legislative support for a ban on CO for fresh-meat packaging.

These efforts have included a petition to the Food and Drug Administration requesting that CO no longer be permitted for meat packaging. The petition does not question the safety of the low (0.4%) levels of CO permitted but instead claims that the practice is deceptive and will result in unsafe products.

CO is useful for fresh-meat packaging because the gas binds with the muscle pigment myoglobin to produce a bright red color. Myoglobin can bind several different substances, including gases, to create a variety of colors. Oxygen in the air, for example, is present in sufficient amount (20%) to produce a bright-red meat color and is often used in meat packaging at elevated levels (80%) to enhance the natural color. When CO binds to myoglobin, it produces a color visually identical to that produced by oxygen but stable longer.

It is widely recognized in the meat industry that consumers select and purchase meat on the basis of color and appearance. Unfortunately, typical oxygen-based fresh-meat color is easily lost during retail display. The longer-lasting color resulting from CO has been the basis for criticism of CO packaging, with claims that consumers might inadvertently consume spoiled or unsafe meat because color might remain unchanged.

While it has been documented that CO-based meat color can remain red even at high levels of bacterial growth, it is highly unlikely that meat which is truly spoiled would be consumed, even if the color was still red, because of the other warning signs such as odors that accompany excessive bacterial growth. FDA has examined this issue thoroughly and requires that meat in low-CO packaging be labeled with a “use or freeze by” date of 28 days after packaging of ground meats and 35 days after packaging of intact steaks or roasts.

One of the criticisms directed at FDA is that CO should have been classified as a color additive and consequently much more rigorously reviewed. However, on at least three occasions, FDA has ruled that CO is a colorless, odorless, “invisible” gas and therefore cannot directly transfer color to meat. Because the FDA definition of a color additive is essentially “a substance that is capable of imparting color,” the issue becomes one of interpretation. It seems relevant to consider that the CO reaction with meat is the same as that of oxygen (another “invisible” gas), both of which result in a virtually identical red meat pigment. The oxygen-based meat pigment is unequivocally accepted as a “normal and expected” color for fresh meat. Because there has been no claim that oxygen is a color additive, it seems inconsistent to claim that CO should be a color additive.

The claim that CO packaging will result in unsafe products is not scientifically sound. There is no greater risk of pathogenic bacteria associated with CO packaging than with any other packaging system currently used for fresh meat. In fact, a valid argument can be made that CO packaging creates opportunities to increase safety. It is important to realize that the presence or absence of bacteria of public health significance on meat is independent of meat color.

CO packaging of meat offers opportunities to utilize complementary processing technologies that inhibit or even kill bacteria. The result is a significant improvement in shelf life in terms of both bacteria and color. Some examples include packaging with elevated carbon dioxide concentrations, scrupulous sanitation and antimicrobial treatments during packaging, and post-packaging irradiation. Ground beef with an advertised 38-day shelf life is commercially available because of such combined technologies (see www.cornerstorefoods.com).

Inevitably, introduction of new technology has the potential to alter the marketplace. In this case, CO packaging competes with the high-oxygen packaging methods for fresh meat. The latter improve meat color but typically utilize antioxidants to counter the oxidative effect of the high-oxygen atmosphere. The use of CO packaging has potential to reduce the market for antioxidants and has resulted in an antioxidant supplier’s petitioning FDA to rescind approval of CO packaging for fresh meat.

Certainly, it is essential that consumers be informed regarding food safety and be protected from unsafe practices. Consumers should be allowed to make informed decisions in the marketplace. Because scientific studies have validated the safety of low-CO packaging technology for fresh meat, it seems appropriate to let the marketplace decide the success or failure of the process.

Joseph G. Sebranek ( [email protected] ), a Fellow of IFT, is University Professor, Depts. of Animal Science and Food Science & Human Nutrition, Iowa State University, Ames. Melvin C. Hunt ( [email protected] ) is Professor, Dept. of Animal Sciences & Industry, Kansas State University, Manhattan. Daren P. Cornforth ( [email protected] ) is Professor, Dept. of Nutrition & Food Sciences, Utah State University, Logan. M. Susan Brewer ( [email protected] ) is Professor, Dept. of Food Science & Human Nutrition, University of Illinois, Urbana. All are Professional Members of IFT.