Double packaging systems reduce irradiated meat odor.

Before processors sell products that have been treated by electronic pasteurization techniques, they may want to know how double packaging systems will reduce odors caused by irradiating meat. Longer shelf life is an added benefit that irradiation provides in certain cases. Research also shows that the dark, firm dry variety of pork best resists the development of odor.

Researchers at Iowa State University follow a double-packaging strategy because odors caused by irradiation stay inside the package, no matter how long you store meat. When pork loins are only vacuum-packaged, odors can build during the longer shelf life that irradiation gives a product. Double packaging involves individually packing meat with oxygen- permeable film and then repackaging several individual packages in large vacuum bags. The vacuum bags are removed a few days before marketing or consuming the product.

When you only vacuum-package a product, you open the bag and can smell the irradiation odor, researchers explain. That could discourage consumers from taking advantage of irradiation's assurance of a pathogen-free product. Dark, firm dry cuts of pork can benefit most by the irradiation process. These cuts are juicy and tender, but also are very susceptible to microbial spoilage. So a prolonged storage time would ordinarily be harmful to their freshness. Irradiation can extend the length of storage time and enable companies to sell them as fresh cuts.

The three types of pork-normal; pale, soft exudative; and dark, firm dry-all become redder after irradiation, especially the pale cuts. The extra red color is a benefit to consumers of pork and is a contrast to beef, which becomes brown after irradiation. The pale, soft exudative pork cuts become redder with irradiation, but they are more susceptible to off-odors. Nonirradiated cuts of pale pork are unattractive to consumers because of their lack of color. If the color is appealing after irradiation, and the off-odor can be reduced by packaging, irradiated meat may be accepted by consumers.

Irradiated dark, firm dry pork tends to offer the best commercial prospects and has fewer problems in storage. It has higher water-holding capacity, and its yield will be increased if it is used in further processing. Those meat products could be juicier and more tender than others.

Further information. Dong Ahn, Department of Animal Science, 2276 Kildee Hall, Iowa State University, Ames IA 50011; phone: [phone]; fax: [phone]; email: [e-mail] <mailto:[e-mail]>.