In brief.

Recent outbreaks of E. coli in the United States have increased consumer awareness and heightened concern about the safety of fresh fruits and vegetables. With evidence that E. coli is becoming a problem in ready-to-eat foods, someresearchers believe that they may have a solution: irradiation.

They consider irradiation to be the only definitive way to eliminate pathogens in ready-to-eat products. Right now, ready-to-eat products, such as spinach and lettuce, are rinsed with chlorinated water to kill any bacteria on their surface. The problem is that with some outbreaks of E. coli, the bacteria were not just on the surface but inside the product. In that case, irradiation could be the only solution for killing the bacteria.

The process of irradiation can be performed using a linear accelerator, in which a filament heats up and boils electrons, which are then accelerated to almost the speed of light. Because electrons have a small mass, they can be controlled using magnets. The linear accelerator uses a magnet to sweep the electrons over a conveyor belt. This creates a shower of electrons. A product is moved below, absorbing the electrons' energy which causes ionization to occur. Ionization disrupts the DNA of the living organism. It affects only living organisms such as bacteria. It does not affect meat cells, because meat cells are no longer living organisms.

While irradiation seems to be an effective solution for killing bacteria in ready-to-eat foods, the FDA has not approved the technology for this use.

Contact: Dennis Olson, Department of Animal Science, Iowa State University, 194 Meat Lab, Ames, IA 50011. Phone: [phone]. Fax: [phone]. Email: [e-mail].