Kathy Bernard, of the U.S. Department of Agriculture Food Safety and Inspection Service, said it is important to know the wattage of your microwave oven.
"To find it, look on the inside of the oven door or in the owner's manual, or you can test how long it takes to boil a glass of water. If it takes 2 minutes or less it's a very high-wattage oven, around 1,100 watts. Four minutes or longer it's a lower wattage -- around 625 watts," Bernard said in a statement. "If your microwave's wattage is lower than the wattage recommended on the package cooking instructions it will take longer than the instructions specified to cook the food. The higher the wattage the faster it will cook food."
If cooking instructions don't recommend cooking the product in a microwave, then don't, Bernard said.
To cook food safely in a microwave, cover with a lid or microwave-safe plastic wrap, leaving a corner open to release steam.
"The temperature should be 165 degrees Fahrenheit, unless otherwise stated on the label," Bernard said. "That's the internal temperature that will kill any harmful bacteria if present. Use a thermometer."
If leftovers are being stored in a mini-fridge, make sure it is 40 degrees F or lower. Having a thermometer is key to checking food is cooked hot enough and stored cold enough, Bernard said.