Sanghyup Jeong, a visiting assistant professor in biosystems engineering at Michigan State University, loads samples of lettuce into a prototype x-ray machine to kill bacterial pathogens.
The patented process, from Rayfresh Foods Inc., Ann Arbor, Mich., has been in the works for more than 10 years. It has been tested at Michigan State University, East Lansing, for the last three, resulting in data that supports the process’ ability to kill foodborne pathogens and extend the shelf life of produce.
Rayfresh’s process is a low radiation X-ray that has shown it can kill 99.9% of foodborne pathogens, including E. coli 0157: H7, on both meat and produce items. The company was contracted by Omaha Steaks, Omaha, Neb., to build its first full-scale X-ray irradiation machine in 2008, and should be finished with the machine by August, said Pete Schoch, president. The machine will also be able to handle foodservice-size bags of lettuce, he said, although that will not be its purpose for Omaha Steaks.
“We built the first machine, but it didn’t run as fast as we were told it would, so we had to rebuild parts of it,” Schoch said.
Schoch is especially optimistic about Rayfresh’s process for foodservice lettuce and spinach, he said, in response to the U.S. Food and Drug Administration’s August decision to allow food processors to use irradiation on fresh spinach and iceberg lettuce to kill E. coli and other pathogens.
“There’s significant interest in the technology and how it might be used on leafy greens,” Schoch said. “And we’re interested in the leafy green market.”
The company custom builds the machines, so it has yet to build a full-scale irradiation machine specifically for produce.
“They’re a couple million bucks, so we’re not keeping them in our pockets,” Schoch said.
The two irradiation methods currently in the market use gamma radiation or electron beam radiation. Both of those methods require products to be shipped to a separate building specifically for radiation. A big benefit of X-ray radiation is that it would be able to be built directly into a packer’s line, not requiring the produce to be shipped to another building.