Haiqiang Chen, Ph.D., of the University of Delaware is busy developing a device using ultraviolet (UV) light to kill foodborne pathogens on fresh produce in consumers’ homes and elsewhere. His UV light oven, which is about the size of a microwave oven, will combine UV light with stirred-up water to reduce Salmonella and other bacteria and viruses that can contaminate fresh produce.

Dr. Haiqiang Chen with his UV light oven in the lab at the University of Delaware. (Photo by Wenbo Fan)
Haiqiang Chen with his UV light oven in the lab at the University of Delaware. (Photo by Wenbo Fan)
“At home, when the fresh produce reaches you, it might not be completely free of foodborne pathogens,” Chen said in a news release. “Typically, consumers don’t wash fresh produce if it has been pre-washed, and those who do generally just wash it a couple of times with tap water. There’s been nothing that’s really effective that you can use at home to ensure clean produce, so the idea was to develop something that can be used in the home.” Chen, who is a professor of food science in UD’s College of Agriculture and Natural Resources, has developed the technology and is currently working with the university’s Office of Economic Innovation and Partnerships to patent and commercialize it. He said the UV oven will be easy to use and could also have applications in restaurants, cafeterias, hospitals and commercial kitchens. The oven will have a simple control panel to allow users to adjust treatment time and will offer a fixed UV intensity. “The decontamination comes through two sources, UV and water. The UV will kill pathogenic bacteria and viruses but the bad thing about UV is that it doesn’t penetrate through solids, although it can penetrate through clear water,” Chen said. “The water will wash off the pathogens from a food surface and whenever they get into the water, they will be killed almost immediately.” Chen compared the device’s efficacy to that of washing produce with plain tap water. He applied both under two simulated Salmonella pathogen contamination scenarios: spot-inoculation, in which he contaminated a piece of produce in a particular spot, and dip-inoculation, involving contaminating the entire piece of produce. After using samples of lettuce, spinach, tomato, blueberry and strawberry in the two scenarios, Chen found that the UV light oven decontaminated the fresh produce much more effectively than washing it with plain tap water. The oven could kill 99.7 percent of the Salmonella on the dip-inoculated lettuce, while the tap water washing could only kill 59.3 percent, he noted. “For spot inoculation, the UV is a lot better. It showed a lot of reduction. It can kill 99.999 percent of Salmonella spot-inoculated on tomatoes – it’s basically gone,” Chen added. The professor said that the UV oven method will not heat fresh produce and will not have a negative effect on its sensory properties. “The produce will be cold. You put it in and take it out, and nothing about the taste changes,” Chen said.

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