Thank you for your question.
According to the Food Safety and Inspection Service in a publication
dated April 2002, as a general rule all foods will be safe as long as
the power has been out less than 2 hours.
The refrigerator will keep food safely cold for about 4 hours if it
is unopened. A full freezer will hold the temperature for
approximately 48 hours (24 hours if it is half full) if the door
They go on to explain:
Always keep meat, poultry, fish, and eggs refrigerated at or below 40
ºF and frozen food at or below 0 ºF. This may be difficult when the
power is out. Keep the refrigerator and freezer doors closed as much
as possible to maintain the cold temperature. The refrigerator will
keep food safely cold for about 4 hours if it is unopened. A full
freezer will hold the temperature for approximately 48 hours (24 hours
if it is half full) if the door remains closed. Obtain dry or block
ice to keep your refrigerator as cold as possible if the power is
going to be out for a prolonged period of time. Fifty pounds of dry
ice should hold a 18-cubic foot full freezer for 2 days.
Never taste food to determine its safety! You will have to evaluate
each item separately. If an appliance thermometer was kept in the
freezer, read the temperature when the power comes back on. If the
appliance thermometer stored in the freezer reads 40 °F or below, the
food is safe and may be refrozen. If a thermometer has not been kept
in the freezer, check each package of food to determine the safety.
Remember you cant rely on appearance or odor. If the food still
contains ice crystals or is 40 °F or below, it is safe to refreeze.
Refrigerated food should be safe as long as power is out no more than
4 hours. Keep the door closed as much as possible. Discard any
perishable food (such as meat, poultry, fish, eggs, and leftovers)
that have been above 40 °F for 2 hours.
In addition, this site includes a handy chart of refrigerator foods,
What to save and when to throw it out if held above 40 ºF for over 2
Food Safety and Inspection Service
United States Department of Agriculture
Additional information that may interest you:
Guidelines for Food Safety During Short-Term Power Outages
Consumer Fact Sheet by Linda Harris, Specialist in Microbial Food
Safety, Department of Food Science and Technology
University of California, Davis
I hope you find this information helpful.