The norovirus family is actually made up of multiple related viruses, which are the most common cause of gastroenteritis in developed countries. They typically make their way onto fruits and vegetables when feces-tainted water runs into fields where crops are growing, or when food is handled by norovirus-infected people.
One method of killing the viruses involves irradiating produce by subjecting it to gamma rays or X-rays. The dose of radiation that's required to eliminate all of the microbes that may be present, however, is high enough that it can negatively alter the chemical qualities of the produce.
With this limitation in mind, scientists at Quebec's Institut National de la Recherche Scientifique (INRS) looked to a combination of cranberry juice and citrus extract. This can be sprayed directly onto fresh produce, forming an edible coating.
Organic acids and micronutrients known as polyphenols, which are abundant in the juice and extract, proceed to inhibit viral activity. With the microbes thus disabled, a much smaller amount of radiation is required to subsequently kill them.
When the spray was used on lettuce in lab tests, for instance, only half the usual irradiation treatment time was needed in order to eliminate norovirus. The coating can in fact thoroughly kill off the viruses all on its own, without any help from irradiation, although considerably more of the juice and extract is required.
The institute is now looking for industry partners that may be interested in commercializing the technology. A paper on the research, which is being led by Prof. Monique Lacroix, was recently published in the Journal of Applied Microbiology.