OSU makes oysters safer to eat

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Oregon producers sold $3 million of farmed oysters in 2011. (Photo by Lynn Ketchum.)
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Improved purification method keeps oysters alive and doesn't sacrifice taste or texture

Oregon State University has improved an old method of making oysters safer to eat. The improved process nearly rids them of the bacteria Vibrio parahaemolyticus, which can cause gastroenteritis, an infection marked by severe abdominal pain, vomiting and diarrhea. Each year in the U.S., more than 40,000 cases of the illness are linked to seafood, particularly raw oysters.

The method that OSU improved is called depuration, in which oysters are placed in tanks of clean seawater at room temperature. The shellfish expel most of the bacteria that's in them into the water, which is then cleaned by a manmade filter and sterilized with ultraviolet light. But more than 10 percent of the Vibrio bacteria still remain.

So OSU chilled the water in addition to using the UV light. This eliminated 99.9 percent of the bacteria. The system is cheap to build and uses less electricity than methods that rely on freezers, heat, pressurization and radiation.

Source: Yi-Cheng Su, OSU professor of seafood microbiology and safety; OSU Extension Service's 2011 Oregon County and State Agricultural Estimates; the U.S. Centers for Disease Control and Prevention.

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