August 11, 1998

The USDA has advised consumers that using a meat thermometer when cooking hamburger, not the internal color of the meat, is the best way to determine whether it is safe to eat. Ground beef must be cooked to 160 degrees to eliminate harmful bacteria such as Escherichia coli O157:H7.

The USDA-FSIS said the emphasis on using a meat thermometer results from research that indicates some ground meat may turn prematurely brown before a safe internal temperature has been reached.

Thomas J. Billy, administrator of the USDA-FSIS, said the phenomenon of premature browning may be more prevalent than originally thought and may occur under normal consumer handling conditions. He said the FSIS is thoroughly investigating the issue.

"We are conducting a survey and risk assessment to confirm and extend observations on the premature browning effect," Billy said. "In addition, FSIS will convene an open meeting in the near future to discuss all of the issues surrounding safe cooking of hamburger."

One issue being discussed relates to other research findings that present the opposite of the premature browning effect. Some ground meat patties that are being cooked to 160 F and above remain pink.

Billy said the FSIS will call for additional research on this and other issues. Currently, FoodNet, the foodborne disease surveillance system sponsored by the CDC and USDA, is analyzing data from E coli case-control studies to determine risk factors for the illness.

For further food safety information, call the USDA's nationwide, toll-free meat and poultry hotline at 1-800-535-4555, or visit the USDA's Food Safety Inspection Service Web site.