The uneven nature of microwave cooking can make it a dangerous way to prepare frozen raw foods. When not all of the food is heated to a safe temperature, pockets of bacteria can survive and sicken people.

U.S. Department of Agriculture food safety experts and major food companies offer several tips for preventing that.

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KNOW YOUR MICROWAVE

Microwave cooking instructions are calibrated to cook food to a safe temperature based on particular wattages, or power. Food takes longer to cook safely in a microwave with lower wattage than one with higher wattage.

But checking your user manual for wattage ratings may not be enough. A microwave's actual output can differ from whatever figure the manufacturer states, and it can deteriorate over time.

To test your microwave, place several ice cubes in water and stir to make sure the water is ice cold and then remove any remaining ice and discard. Then measure 1 cup of ice water and set it in the microwave. Heat on high for 4 minutes, but watch to see when the water boils. If the water boils in less than 2 minutes, the oven has at least 1,000 watts.

If water boils in 2 1/2 minutes, the microwave produces about 800 watts. If water boils in 3 minutes or longer, it is a low-wattage oven producing about 700 watts or less.

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CHECK THE TEMPERATURE

Food safety experts recommend that consumers use an instant-read food thermometer to check the final temperature of microwaved food. Be sure to check in several places to ensure there are no cold spots. Continued...