Irradiation can get at those hard-to-reach places in produce where water and chlorine are not as effective, according to new findings from the U.S. Department of Agriculture.
Microbiologist Brendan Niemira said his research looked at protected areas like lettuce leaves to discover how well irradiation works to kill hidden pathogens found there.
Niemira learned bacteria in cells on the surface of the leaves was more susceptible to irradiation than the inside of leaves.
He also found ionizing radiation reduced pathogens in spinach and lettuce leaves by 99 percent, and that salmonella died more readily than samples with E. coli.
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“The result of the study is E. coli certainly dies when you irradiate it,” he said. “Irradiation is still capable of killing E. coli in a way that chlorine is not.”
Chlorine and ozonated compounds are regularly used by produce packers and processors to wash fruits and vegetables.
Irradiation is generally used to reduce insects on imported produce, to suppress ripening and extend shelf life.
Niemira said his irradiation findings have food safety applications for industry, citing its potential use as a last step before the produce is shipped to retailers. Spinach could be rinsed, dried, bagged and irradiated.
The American Food and Drug Administration is reviewing the food treatment.
Produce risks contamination with bacteria because it generally grows in open fields and is exposed to wildlife, manure and irrigation water.
In future, Niemira will investigate salmonella in tomatoes and biofilms on the surface of leaves and explore consumer acceptance of irradiation practices.
