Research shines light on organic fruit, food safety

Scientists at Washington State University (WSU) have shown that ultraviolet C (UVC) light is effective against foodborne pathogens on the surface of certain fruits and could be used on organic produce as an alternative to chemical sanitizers.

Recently published in the International Journal of Food Microbiology, the method of using UVC light to sanitize surfaces has been around for several years, but this is one of the first times it has been tested and found to be successful on fruits. This is especially promising for organic farmers as the U.S. Food Safety Modernization Act, which aims to help prevent foodborne illnesses and create a safer food supply, will increase government regulations on foods when it’s announced next month.

“UVC radiation is present in sunlight; however, it is completely absorbed by the ozone layer and Earth’s atmosphere,” WSU food safety specialist, Shyam Sablani explained in a recent article. “It has germicidal properties and can be effective against bacteria, mold and viruses.”

UVC light works by destroying nucleic acid and disrupting their DNA but not disturbing the chemical or physical quality of the fruit, Sablani added. In the study, him and his colleagues exposed apples, pears, strawberries, raspberries and cantaloupe to different doses of UVC to determine how effective the pathogen-killing light was against different strains of E. coli and Listeria. They found that the light can inactivate up to 99.9% of pathogens on apples and pears, and that Listeria was more UVC resistant than E. coli.

The best results were found on apples and pears due to their soft skin compared to the rough surfaces of strawberries, raspberries and cantaloupe. The article states that these rough surfaces offer places where pathogens can hide, reducing the effects of UVC light. The article also states that if bacterial contamination levels are high, then UVC technology alone may not be sufficient to achieve the desired level of effectiveness.

However, adding UVC lamps to a fruit packing line does not require major modifications, Sablani notes and UVC lamps enclosed behind protective barriers can be easily set up in a tunnel that exposes fruit to the light as it passes on a conveyor belt.

“Interest in this technology is high because it’s simple to implement and inexpensive,” he added.

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