MOUNT VERNON — When the power goes out, refrigerators and freezers go out too and the food inside them warms quickly. It pays to use caution and common sense before consuming food that has thawed in the freezer or warmed to above 40 degrees in the refrigerator.

The Ohio State University Extension Office in Columbus notes that refrigerator and freezer doors should not be opened until the power comes back on. In addition, a full or nearly full chest-type freezer will hold for 24 hours and perhaps longer. But the food in the average home refrigerator won’t fare as well.

Sometimes it’s just not possible to leave the door closed for hours. But because every door opening lets cold air out and warm air in, make forays into the fridge as fast as possible and make sure the door is re-shut tightly.

Suzanne Dapprich, registered sanitarian with the Knox County Health Department and part of the department’s team that inspects food service operations, said perishable food that has slowly warmed inside a refrigerator without power is at risk.

“If it’s above 41 degrees for more than four hours,” said Dapprich, “throw it out.”

That, she said, is the department’s criteria for restaurants and food service operations, and also applies to home refrigerators and freezers.

She noted that many Coshocton Road area restaurants were without power on Monday morning.

“I’ll be following up on them throughout the day,” she said. “We’ll be making phone calls.”

Dapprich said a full freezer — whether commercial or residential — will “hold” better than a half-full or partially full freezer.

“If you have a doubt about something, throw it out. We certainly want you to be safe, not sorry,” she said.

OSU Extension’s Web site recommends keeping a thermometer on hand for such occasions, or to make a “test packet” of two or three ice cubes in a sealed plastic freezer bag. Leave the bag in the freezer. When the cubes melt, homeowners will know the interior temperature of the freezer has risen above 32 degrees.

The Web site also notes that, “As a general rule, completely thawed foods should not be refrozen. The quality will always be poorer and spoilage may have taken place during the thawing and standing periods.”

The site adds that if a fully stocked freezer has not been opened for 24 hours and the power comes on, it should be left unopened for another 24 hours so food can refreeze before opening the door.