A Purdue University researcher has found a way to eliminate bacteria—and the worries associated with food-borne illness—in packaged foods, such as spinach and tomatoes.

Kevin Keener designed a device consisting of a set of high-voltage coils attached to a small transformer that generates a room-temperature plasma field inside a package, ionizing the gases inside. The ionization turns oxygen into ozone, which kills harmful bacteria, such as E. coli and Salmonella, according to a news release.

Treatment times range from 30 seconds to about five minutes, Keener says.

The longer the gas in the package remains ionized, the more bacteria are killed. Eventually, the ionized gas will revert back to its original composition.

The process uses only 30 to 40 watts of electricity, less than most incandescent light bulbs. The outside of the container only increases a few degrees in temperature, so its contents are not cooked or otherwise altered.

"Conceptually, we can put any kind of packaged food we want in there," says Keener, an associate professor based in West Lafayette, Ind. "So far, it has worked on spinach and tomatoes, but it could work on any type of produce or other food."

Other methods of ozone treatment require adding devices to bags before sealing them to create ozone or pumping ozone into a bag and then sealing it.

Keener's method creates the ozone in the already sealed package, eliminating any opportunity for contaminants to enter while ozone is created.

"It's kind of like charging a battery. We're charging that sample," Keener says. "We're doing it without electrode intrusion.

We're not sticking a probe in the package. We can do this in a sealed package."

Keener says testing has worked with glass containers, flexible plastic-like food-storage bags and rigid plastics, such as strawberry cartons and pill bottles.

His next step is to develop a commercial prototype of the device that could work on large quantities of food.