Ben Swann KFOX Morning News Anchor/Reporter

It's been two years since the biggest power outage in American history. 50-million people lost electricity from New York to Ohio. When the lights finally came back on, plenty of people had lost a lot of food. Since the historic black-out, our consumer experts tested to see how long refrigerators and freezers can keep your food safe without power. Here's what they discovered.

Ramona Grey-Harris loves to cook and always keeps a full refrigerator. So when her power went out for nearly 20 hours, she had a real mess on her hands.

Romona Grey-Harris: "I had to clean the whole refrigerator out."

Consumer Reports wanted to find out just how fast your refrigerator warms up when the power goes out. To do that, testers drilled holes in packages of frozen spinach. Then they inserted sensors to track the temperature. They also used sensors to measure the temperature in the refrigerator and the door compartments over a 24-hour period. The tests show food in some parts of the refrigerator will last longer than others.

Emilio Gonzalez-Consumer Reports: "The lower the food is, the colder it is and the less likely it is to spoil. Whereas the higher it is or on the door, which is typically warmer, it's more likely to spoil."

Consumer Reports' Linda Greene says, as a general rule you should throw out any perishable food in your refrigerator if your power has been off for four hours or the temperature has risen above 40 degrees for more than two hours.

Linda Greene-Consumer Reports: "Poultry and meat, cold cuts and eggs. They can make you sick even if you cook them. Never taste them to see if they're spoiled."

You should also throw our soft cheeses such as mozzarella, ricotta, cottage cheese and cream cheese, also creamy dressings. Butter, hard cheeses and condiments, such as ketchup, jelly and mustard should be fine. As for food in the freezer

Linda Greene-Consumer Reports: "If the food contains ice crystals, it's safe to cook immediately or refreeze it."

If you experience a power outage, open your refrigerator and freezer only when necessary. This will help keep your food cold longer. Now our experts tell us that it's a good idea to put a temperature gauge in your refrigerator and keep the fridge at 37 degrees. Freezers should be kept at zero degrees or below.

For more helpful consumer information, visit *Consumer Reports on the web.

http://www.consumerreports.org/

*Consumer Reports is a fee based website. Many of the articles require a subscription.