Researchers at Washington State University have developed a procedure to reduce the risk of dangerous bacteria in organic produce.

Food scientist Dong-Hyun Kang and his colleagues have tested various methods to reduce E. coli 0157:H7 and two other strains of foodborne bacteria, salmonella and Listeria monocytogenes, on organic fresh lettuce.

After nine months in the lab, they achieved their goal by submerging the produce in an ultrasound tank containing small amounts of malic, lactic and citric acids.

The combined treatment of ultrasound and organic acids has potential for other types of produce as well. But the research showed that some fruits and vegetables, such as tomatoes and strawberries, have skins too sensitive to withstand the treatment.

Despite some limits on its range of use, Kang said, the approach is a feasible way for processors in the food industry to sanitize most types of fresh produce.

"Even local growers could adopt this technology today if they wanted to. It is that simple and straightforward," Kang said. "We developed a simple method because if a procedure like this was difficult at all, no one would use it."

Not only is this new method easy to use, it also has the potential to save the organic food industry a lot of money. Kang said organic acid treatments alone are effective but expensive. Adding ultrasound allowed researchers to reduce the quantity of organic acids needed in the solution from 2 percent to 0.5 percent.

The next step will be to conduct the combined treatment on a larger scale to determine the needed process conditions for organic food industrial applications. The complete results of the current study are forthcoming in the International Journal of Food Microbiology.

-- Steve Brown