Also, ionizing radiation it is not so likely to reduce nutrients such as chlorophyll, carotenoids and valuable antioxidants as thermal processes do, said Dr. Elena Castell-Perez , the third member of the team.
"Ionizing radiation can actually enhance some nutrients such as carotene and other antioxidants," Gomes said. "And irradiated food stays fresh longer."
But no matter how healthy and safe to eat, few consumers would want their lettuce a bit on the mushy side. Consequently, the team was looking for ways to reduce the amount of ionizing radiation without reducing its effectiveness in killing pathogens.
An electron-beam gun is typically used to irradiate food for several reasons, Gomes said. Electron beams will kill pathogens without using a radioactive material for a source. But electron beams also generate ozone, a corrosive form of oxygen, which is a drawback for many applications. However, ozone has a bactericidal function as well.
"Therefore, though it (ozone) was something that was considered detrimental in irradiation facilities, we decided to work to our benefit and use it synergistically with irradiation," Gomes said. "The question we asked was, 'What if we irradiate a bag of fresh produce with enough oxygen inside that it becomes ozone? Will that allow us to decrease the required dose?'"
Working with this concept, the researchers packed the vegetables in Mylar bags filled with pure oxygen, a nitrogen oxygen mix or plain air. Prior to bagging, the team uniformly inoculated both fresh and frozen spinach samples with a cocktail containing either salmonella or listeria cultures. They then subjected the sample bags to various levels of radiation, ranging from 0.2 t
|Contact: Robert Burns|
Texas A&M AgriLife Communications