UV light oven kills foodborne pathogens

A US researcher has developed an ultraviolet (UV) light oven that can decontaminate fresh produce.

Combining UV light with water, the device is designed to look like a domestic microwave oven and will be suitable for use in the home and well as restaurants, cafeterias, hospitals and commercial kitchens.

Haiqiang Chen, professor of food science in the University of Delaware’s College of Agriculture and Natural Resources (CANR), has developed the technology, which will be simple to use, offering a fixed UV intensity and a simple control panel that allows users to adjust treatment time.

“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.”

To test the decontamination efficacy of the oven, Chen compared it to that of simple tap water washing under two simulated Salmonella pathogen contamination scenarios: spot-inoculation, where a piece of produce was contaminated in a particular spot, and dip-inoculation, which is the worst-case scenario and involves the entire piece of produce being contaminated.

Using lettuce, spinach, tomato, blueberry and strawberry samples, Chen found the UV light oven decontaminated fresh produce much more effectively than tap water washing. In the case of the dip-inoculated lettuce, the oven could kill 99.7% of the Salmonella population while the tap water washing could only kill 59.3%.

“For spot inoculation, the UV is a lot better. It showed a lot of reduction. It can kill 99.999% of Salmonella spot-inoculated on tomatoes — it’s basically gone,” said Chen.

Despite being described as an ‘oven’, the device will not heat the produce in any way 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.