Zapping food pathogens at the source

Work to control pathogens in kitchens and food processing centers is getting an assist from cold plasma engineers, who are making appliance surfaces too slick for bugs to stick.

Ferencz Denes, a scientist with the Department of Biological Systems Engineering and the Center for Plasma-Aided Manufacturing, is applying his pioneering work with plasmas to a variety of food safety issues. Denes has a patent through WARF that employs cold plasma technology to modify the surfaces of food-industry materials, such as processing machines, preparation surfaces and packaging, to prevent bacterial attachment and biofilm formation.

The effort is especially important because many of the worst disease-causing pathogens in food, such as Salmonella, E. coli O157:H7 and Listeria monocytogenes, are extremely stubborn and resourceful. They are capable of thriving in the nooks and crannies of food preparation implements, escaping even the most thorough cleaning.

Techniques developed by Denes and Amy Wong, both professors at the Food Research Institute, can follow two steps. The first changes the surface of materials to incorporate anti-microbial agents in extremely thin layers. The second fuses a protective film over the surface to make bacteria incapable of sticking and forming colonies.

The chambers that produce cold plasmas are relatively small, inexpensive and easy to use, and produce oxygen-based plasmas that operate at room temperature.

Plasma-aided manufacturing uses electrically charged particles to alter the surface of materials, giving them unique or superior properties. Often called the “fourth state of matter,” plasmas are formed by adding a gas to an electric field, which causes the gas molecules to split apart and form new compounds.

The sun, stars and 99 percent of matter in the universe are comprised of plasmas; cold plasmas are the same state of matter at ambient temperatures, mild enough to treat organic materials like rubber and plastic.

Plasmas are used in computer chip manufacturing and are used in lighting, polymers and high-performance ceramics. The UW–Madison research team is also looking at the same techniques to improve sterilization of medical devices, such as catheters and implants.