Keeping Oysters, Clams and Mussels Safe to Eat

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http://www.sciencedaily.com/releases/2011/04/110419121347.htm

Keeping Oysters, Clams and Mussels Safe to Eat

ScienceDaily (May 3, 2011) — Eating raw or undercooked mollusks may pose a

safety hazard if they are harvested from waters polluted with pathogenic

microbes, so U.S. Department of Agriculture (USDA) scientists are studying ways

to enhance the food safety of these popular shellfish.

For example, USDA molecular biologist H. Kingsley at Delaware State

University in Dover is exploring new techniques that will decontaminate mollusks

while protecting the seafood's flavor, texture, and color.

Kingsley, with USDA's Agricultural Research Service (ARS), is investigating the

use of a specialized commercial procedure known as high pressure processing, or

HPP, to inactivate viruses. HPP is already used commercially to pasteurize some

juices and meats, and by some shellfish processors to deactivate Vibrio

bacteria. But Kingsley and colleagues are the first to show that HPP also can

inactivate some foodborne viruses.

HPP equipment compresses water to create intense pressures as high as 90,000

pounds per square inch. Normal atmospheric pressure is about 15 pounds per

square inch at sea level.

In tests targeting hepatitis A virus, the cause of a contagious liver disease,

the team showed that an HPP treatment of 60,000 pounds per square inch of

pressure for five minutes inactivated 99.9 percent of the virus in oysters that

had been exposed to the pathogen in laboratory tanks.

The hepatitis A studies led to a collaboration with researchers in Italy, where

raw or lightly cooked Mediterranean mussels, popular in European markets, are

sometimes a vector for the virus. The ARS scientists and colleagues from Italy's

University of Bari found that the 5-minute, HPP treatment inactivated 99.9

percent of the virus in North American blue mussels and in Mediterranean

mussels.

HPP is not perfect. For instance, the pressure needed to inactivate hepatitis A

virus may alter the taste and texture somewhat. Additional research may reveal

ways to mitigate these changes.

Kingsley and his co-investigators have published these and other findings in

Food and Environmental Virology, Virus Research and other scientific journals.

The Dover team is part of the ARS Eastern Regional Research Center in Wyndmoor,

Pa.