U.S. House of Representatives

Committee on Agriculture

Mr. Collin Peterson, Chair

Mr. Chairman and Members of the Committee:

Thank you for the opportunity to visit with you today about some of the
current issues associated with technologies in the meat industry. My
name is Joe Sebranek. I am a University Professor in the Department of
Animal Science and the Department of Food Science at Iowa State
University where I have been responsible for research and teaching in
Meat Science for the past 32 years. I received a joint Ph.D. in Meat and
Animal Science from the University of Wisconsin-Madison prior to joining
the faculty at Iowa State. I have conducted research and published
several peer-reviewed scientific reports on meat packaging technology
which I understand to be the focus of this hearing. In particular, I
have researched the use of carbon monoxide in fresh meat packaging which
has been criticized as a "deceptive and hazardous" technology. This is
an issue that I would like to address today because, in my opinion,
there is no scientific basis for these claims.

When considering fresh meat packaging technology, it is important to
understand the options available for packaging of fresh (refrigerated,
unfrozen) meat and advantages and limitations of each. Meat is a highly
perishable commodity and packaging plays a very critical role in
protecting meat products from contamination and spoilage during
distribution to consumers. For example, vacuum packaging of wholesale,
primal cuts of meat, which is one packaging option, is universally
practiced for wholesale packaging because it results in a several-fold
longer refrigerated storage time without spoilage in comparison with
products exposed to air. It is important to note that vacuum packaging,
which consists of placing meat into a gas-impermeable bag or container
and evacuating all of the air before sealing the package, is effective
because it eliminates oxygen from contact with the meat. Eliminating
oxygen prevents growth of aerobic bacteria which are the primary
spoilage bacteria of fresh meat. Eliminating oxygen also prevents
development of oxidative rancidity and associated off-flavors at the
same time. Unfortunately, vacuum packaging is not a suitable option for
retailing fresh meat because in vacuum, meat color reverts to a dark
purple-red which is not attractive to consumers. There have been several
attempts by the meat industry in the past to offer fresh meat to
consumers in vacuum packages but these attempts have been unsuccessful
because of the color issue. However, the advantage of eliminating oxygen
from contact with fresh meat in terms of greatly improved storage
stability is an important point to remember.

The second option for packaging fresh meat is aerobic packaging. This
approach uses a permeable, clear film which allows oxygen from the air
to permeate the film and contact the product surface. The oxygen is
bound by the meat pigment myoglobin and in doing so, forms oxymyoglobin
which has a bright, cherry-red color. This is the color clearly
preferred by consumers as documented by many, many studies on meat
color. Unfortunately, oxygen contact allows rapidly-growing aerobic
spoilage bacteria to proliferate and also initiates chemical oxidation
reactions that eventually result in rancid flavors. Consequently, the
keepability or shelf-life of fresh meat in an aerobic package is
relatively short, consisting of a few days to a week or two at most,
depending on the meat cut and how it has been handled.

The third option for fresh meat packaging that has developed more
recently is use of a impermeable film similar to a vacuum package but
includes first evacuating the air from the package and replacing the air
with a specified mixture of gases that provides for better control of
product properties. This is modified atmosphere packaging or MAP. The
air in the atmosphere we live in is 75% nitrogen, 21% oxygen, and less
than 1% carbon dioxide with minute amounts of a few other gases, thus,
changing the gas composition in a package from that of air is considered
MAP. For fresh meat, two forms of MAP have been utilized. One approach
is to use an oxygen concentration greater than air, as much as 80%, in
MAP. This results in red color that may last as long as 10 to 14 days
compared to about five days in a conventional oxygen-permeable package.
Keep in mind that contact with oxygen allows many of the same effects as
conventional aerobic packaging; that is, aerobic bacterial growth and
development of rancid flavors over time. It has also been observed that
high oxygen exposure can result in what is called "premature browning"
when the meat is cooked. This means that meat turns brown at cooking
temperatures lower than what is typical. Some scientists have expressed
concern that consumers may not thoroughly cook products, particularly
ground beef, to achieve bacterial safety in this case because the cooked
color will look "well-done" when that is really not the case.

This brings us to the use of carbon monoxide in MAP. This is an
alternative MAP system that has been approved by the regulatory agencies
and has been available for a little more than four years. This system
uses 0.4% carbon monoxide (CO), 30% carbon dioxide (CO~2~) and 69.6%
nitrogen (N~2~). This approach produces very attractive meat color
because CO binds to meat pigment in the same way as oxygen, only with a
stronger bond, and produces a cherry red color that is visually
identical to that of oxgmyoglobin. The most immediately obvious
advantage of this approach is a stable red color that can last for 28 to
35 days in refrigerated storage. This has been the basis for much of the
criticism of this packaging concept, with claims that this is "deceptive
and hazardous". There is simply no scientific basis for these claims.
Carbon monoxide is colorless and affects meat color the same way as
oxygen, that is, by combining with myoglobin. The color is derived from
the meat pigment in both cases, not an external coloring agent.

It has been suggested that the color will last too long, resulting in a
spoiled product that still looks good. I would like to point out that
spoilage also manifests itself in other ways, the most obvious of which
is odor. Thus, there are other very obvious warning signs of spoilage.
Further, the MAP with CO packages include "use by" and/or "freeze by"
dates to give consumers guidelines on the time by which the product
should be used. It is also important to remember that elimination of
oxygen prevents aerobic bacterial growth and dramatically slows spoilage
compared with aerobic packaging. Perhaps more importantly, very recent
research by Dr. Michael Doyle at the University of Georgia has shown
that MAP with CO repressed the growth of pathogenic *E. coli* O157:H7 on
ground beef compared to conventional aerobic packaging, thus there is an
impact on this pathogen as well. Dr. Doyle concluded that
"...refrigerated or mildly temperature-abused MAP-CO ground beef has
better quality and microbial safety characteristics than overwrapped
beef stored under similar conditions." Recent studies have also shown
that meat cuts in high oxygen atmospheres were less tender than those
packaged without oxygen probably due to the activity proteolytic,
tenderizing enzymes that are known to be inhibited by oxidative
conditions.

A final issue raised by some critics of MAP-CO system is the human
exposure to CO, a recognized environmental hazard. However, at 0.4% in a
package, it would require over 200 packages to exceed what the
Environmental Protection Agency considers a limit for exposure to CO.
This issue has been addressed many times and it is widely accepted that
CO exposure from meat packaging is negligible.

Consequently, the use of MAP-CO for fresh meat offers numerous
significant advantages including improved product appearance, better
flavor, greater tenderness, and suppression of bacterial growth. The use
of CO provides all the advantages of a vacuum package for storage
stability with the attractiveness of an aerobic package for retail
display. To quote one of my colleagues in Meat Science, Dr. Daren
Cornforth of Utah State University, "What's not to like about that?"

There is one other point to be made. Carbon monoxide packaging can be
combined with other antimicrobial treatments to dramatically improve
fresh meat shelf-life and safety while retaining attractive color. A
good example is irradiation, which when applied to ground beef to reduce
or eliminate bacteria, typically results in a color change to a
purple-red resembling vacuum packaged meat. However, if ground beef is
irradiated in MAP-CO, cherry red color is retained while bacteria are
reduced to very low numbers. Commercial ground beef processed with this
combination has been advertised with a 38-day refrigerated shelf life
which is a dramatic improvement over the typical 5 days. I fully
recognize that irradiation is itself a controversial process. However,
this provides a good example, in my opinion, of the often-unrecognized
potential to combine MAP-CO with other technologies to maximize food
quality and safety. Packaging with CO should continue to be available as
an option to allow for development of new and innovative combinations of
packaging with other new technologies to maximize quality and safety of
fresh meat.

Finally, the MAP-CO technology has now been used commercially for almost
five years and there have been no complaints that I am aware of from
consumers about unexpected or unusual spoilage. This technology is
establishing a track record that has been free of problems and has not
been an issue with consumers. It seems to me that it is most appropriate
to let the marketplace decide the ultimate success or failure of this
technology.