Producer question: For several years now the meat industries have studied irradiation as a way to eliminate food safety hazards. Is it any closer to becoming a reality?
Olson's response: Irradiation of meat and poultry is quietly gaining favor in the respective industries. All food companies know they're as susceptible to bacterial nightmares as companies who have already faced product recalls. Meat and poultry product recalls have averaged more than one a week so far this year. That's twice as many as two to three years ago. While not all of these recalls are due to pathogenic bacteria contamination, most are.
In 1993, when hundreds of people became ill and several children died from eating undercooked hamburgers at a Jack-in-the-Box restaurant in the Pacific Northwest, consumers' food concerns changed dramatically. Before that incident, consumers were most concerned about pesticides in their food due to a nationwide media frenzy in 1989 about Allar being sprayed on apples.
Now consumers' greatest food safety concern is bacteria in their food. Yet, few in the food industry recognized the intensity of the consumers' concern about food safety or the ramifications that would result.
The first ramification was the declaration of E. coli O157:H7 as an adulterant rather than a contaminant in raw ground beef. There is zero-tolerance for an adulterant, and when it is found in a product, it must be pulled. The result has been dozens of recalls involving millions of pounds of ground beef. The fact that only about one lot of ground beef tests positive for E. coli O157:H7 for every 1,000 lots sampled means no effective sampling program can be economically implemented to assure zero defects. Hence, the ground-beef industry can only hope that USDA doesn't sample their product or if it does, that the sample tests negative for E. coli O157:H7.
A second ramification triggered the revamping of the inspection system and bacterial testing requirements. The expected outcome is fewer illness of people eating meat and poultry products. It will take years to determine if this outcome develops. What's more, we may never know because the methods used to estimate illness numbers keep changing. We do know that the Hazard Analysis and Critical Control Points program will not destroy pathogenic bacteria. HACCP's objective is to reduce or prevent contamination from occurring.
The latest industry shocker was the recall of 50 million pounds of processed meats produced by Bil Mar and Thorn Apple Valley in early 1999. Those events shook the foundation of the industry, because everyone thought the products were already safe – afterall, they had been cooked. The meat and poultry industries have always relied on cooking to produce safe products. Whether cooking was done in the processing plant, restaurant or home, it was the sole technology used to kill pathogenic bacteria. The prevailing attitude was to cook products under inspection to produce a safe product or to educate the food-service worker or consumer to handle and cook meat and poultry products safely.
But we know that a single cooking process is not sufficient to always render products safe. With the recalls of ready-to-eat meat products this year due to Listeria monocytogenes, we know that even though there is only a brief time between cooking and packaging, it is still sufficient for potential contamination to occur.
Ideally, we need to destroy pathogens after products are packaged so that no further contamination can occur. Irradiation is the only technology that destroys pathogens after packaging and that is economically feasible.
In the United States, irradiation is approved for use with poultry and meat. Refrigerated or frozen poultry are approved at dosages between 1.5 kilograys and 3.0 kGy to control pathogenic bacteria. Meat, including pork, is approved with a maximum dosage of 4.5 kGy for refrigerated product and 7 kGy for frozen. Micro-organisms are more resistant to irradiation in frozen products than refrigerated products, which is why a higher dose is needed to achieve a microbial kill. USDA's final rules for implementing irradiation in meat are expected by late fall.
While the primary objective of food irradiation is to destroy pathogenic bacteria, it also substantially reduces spoilage organisms. A two- to three-fold increase in shelf life typically occurs after irradiation.
Meat quality changes can occur in irradiated products that consumers might notice. Those changes generally relate to changes in odor, color and flavor. To minimize quality changes, products need to be packaged without oxygen present, as is the case with vacuum or modified-atmosphere packages. Even then there still can be slight odors unique to irradiation in the raw product and a slight increase in redness in irradiated pork. But, both quality changes are reduced drastically when the products are cooked.
In the near future, you will see irradiated ground beef enter the market place. Titan Corporation and Cloverleaf Cold Storage are building an irradiation facility in Sioux City, Iowa. IBP, Excel and other companies have committed to irradiating ground beef at this new facility once it is operational. Colorado Boxed Beef has announced its intention to irradiate ground beef in the Food Technology Services irradiation facility in Mulberry, Florida, after USDA issues its final implementation rules. Once irradiated ground beef enters the market place, it will tell us how consumers react to these products. If these initial market trials are successful, as expected, it is likely that irradiation for use on many more meat products will spread as quickly as new facilities can be built.
Dennis Olson is a meat scientist at Iowa State University, Ames, Iowa.