A&T Food Scientist Advises on Power Outages



February 7, 1997

Greensboro, NC: The combination of ice, wind and trees often results in a loss of electricity. At times, power outages are short and require nothing more than clock resetting. At other times, however, homes may go hours, or even days without power. During these times, food may spoil and present health risks, if the proper precautions are not taken.

"Consumption of food contaminated with bacterial pathogens can result in health consequences ranging from mild to severe foodborne illness," said Dr. Aubrey Mendonca, a food safety research scientist with North Carolina A&T State University's School of Agriculture. "During a power outage, the safety and quality of refrigerated or frozen foods depend on maintaining cold temperatures to inhibit the growth of bacteria."

"Generally, many foodborne bacteria begin to grow when food warms to about 45 oF, and the bacteria grow more rapidly as the temperature exceeds 45 oF," said Mendonca. "Refrigerated foods should be safe within four hours of a power outage, as long as the refrigerator is not opened too frequently. Frequent opening of the refrigerator raises the temperature and speeds up the spoilage of food due to rapid growth of foodborne bacteria."

According to Mendonca, if the temperature in the refrigerator starts to rise above 40 oF (4.4 oC), foods should be placed in plastic bags and transferred to a cooler containing ice. Frozen foods will remain at freezing temperatures for about two days when the freezer is full and for about one day when it is half full. If the freezer is not full, packages of frozen foods should be grouped together to form an "igloo" to maintain freezing temperatures in these foods.

Frozen raw meats, poultry, and seafood should be grouped separately in a corner of the freezer or in a tray so that if they start to thaw, their drippings will not contaminate other foods. Dry ice, block ice, or freeze-pack inserts may also be used to help maintain freezing temperatures.

"The decision to discard or keep refrigerated or frozen foods should not be based only on appearance and odor, because some foods may appear and smell normal although they contain sufficient numbers of bacterial pathogens to cause foodborne illness," said Mendonca. "Suspect food should never be tasted to determine spoilage."

The type of food and the length of time that the food was held above 40 oF must also be considered. Foods that should be discarded if held above 40 oF for more than two hours include:

• fresh or cooked meat, poultry, and seafood
  
• casseroles
  
• soups and stews
  
• cooked vegetables
  
• opened canned meats
  
• eggs and egg dishes
  
• dairy products (except for butter, margarine, and hard or processed cheese)
  
• custard or cream-filled pastries
  
• cooked pasta

Foods such as fresh, dried, or candied fruits, fruit pies, peanut butter, salad dressings, fruit preserves, taco and barbecue sauce, catsup, mustard, olives, and pickle relishes can be kept even if they were held above 40 oF for more than two hours. Frozen meats, poultry, and seafood need to be checked carefully. If, when power is restored, they still contain ice crystals and feel cold, they can be refrozen. If they are fully thawed and remained above 40 oF for over two hours, they should be discarded. Fully cooked foods that may have come in contact with drippings from thawed raw meats should also be discarded.

Mendonca recommends that shelf-stable foods be kept on hand in preparation for long power outages. Some examples of shelf-stable foods are:

• tuna, corned beef, soups and stews, fruit and fruit juices, vegetables, and evaporated milk
  
• powdered milk, breakfast cereal, beef jerky, toasts, peanuts
  
• jams, jellies, and marmalades

Canned meats, soups and stews, and evaporated milk should be consumed as soon as possible after they are opened and leftovers should be discarded if not consumed within two hours.

"Foodborne illness needs to be taken seriously. A mild case may cause a person to be absent from school, work, or recreational activities until the illness subsides," said Mendonca. "More severe cases of foodborne illness can result in fever, abdominal pain, diarrhea, and dehydration, which may require hospitalization. Furthermore, some foodborne pathogens invade the blood and membranes of the brain, resulting in septicemia and meningitis, respectively."

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For more information, please contact Dr. Aubrey Mendonca, NC A&T School of Agriculture, (336) 334-7328.