A group of Texas A&M University researchers say they’ve developed a system that cuts by as much as a half the amount of radiation needed to kill most salmonella, E. coli and other pathogens on fresh produce while preserving the quality of the product.


Packing produce in a Mylar bag filled with pure oxygen allowed researchers to significantly reduce the amount of radiation needed to kill pathogens, said Carmen Gomes, a Texas A&M food safety engineer and one of the project’s leaders. Higher amounts of radiation can cause leafy vegetables to decay and lose freshness.


“Reducing the amount of radiation is not so much a safety measure as it is a way to preserve quality of the produce,” Gomes said in a Dec. 6 statement on the Texas AgriLife Research website. The researchers are part of Texas A&M’s extension system.


Radiation doses used by the researchers were enough for a 100,000-fold reduction in pathogens. That corresponds to a 99.999% kill rate, according Rosana Moreira, another researcher on the project.


“If you had 100,000 bacteria in your vegetable, it means you would end up with just one bacteria still living,” Moreira said in the statement.


E. coli and other pathogens have caused growing concern in the fresh produce industry in recent years after illness outbreaks linked to tainted romaine lettuce and spinach.


Found in the intestines of cattle, E. coli may be spread through tainted irrigation water, runoff from nearby farms or by wild animals.


The lower radiation doses used by the Texas A&M researchers left no residue on the vegetables and the products are safe for human consumption after the process, Gomes said.


“It is analogous to the heat treatment when you expose milk, juices and cans of vegetables to very high temperatures for a period of time to kill pathogens,” Gomes said.

Food irradiation has been in use for almost 50 years in the U.S. But just a fraction of fresh produce is treated with irradiation, and the technology has struggled to gain consumer acceptance. Much of the fresh produce sold in the U.S. is treated with chlorine rinses.