Q. Does microwaving kill the bacteria in food that can cause food poisoning?
A. Yes, if the food is cooked properly to avoid uneven heating. But there have been cases of food poisoning (e.g., Salmonella), from frozen foods?particularly pot pies?not microwaved properly.
For packaged products, it’s important to follow directions. And it helps to know the wattage of your oven, because the amount of time needed to zap potentially harmful bacteria varies depending on a unit’s wattage. That information is usually found on or near the inside of the oven door. If it isn’t, you can estimate it with the following test.
Time-to-Boil Test. Fill a two-cup measuring glass with water and ice cubes; stir until ice cold. Discard ice cubes; pour out water to make one cup. Heat in the microwave on high for four minutes, watching through the window for when it boils.
- If it boils in less than two minutes, it’s a high-wattage oven of 1,000+ watts.
- If it boils in two-and-a-half minutes, it’s medium wattage?about 800.
- If it boils in three minutes, it’s a low-wattage oven of 650 to 700.
- If it takes more than three minutes or hasn’t boiled by four minutes, it is a very-low-wattage oven of 300 to 500.
Adjust Cooking Time for Wattage. If the package’s microwave instructions give a range of times, use the minimum for high-wattage ovens and the maximum for low-wattage ovens. (Be aware, however, that even the minimum cooking time may overcook food, so you need to know your microwave’s tendencies.)
Stouffer’s, for example, provides instructions assuming a 1,100-watt oven (though it doesn’t say that on the package). If your oven has a lower or higher wattage, adjust cooking times accordingly.
Cooking Evenly Is Key to Safety. In addition to cooking to the proper temperature, it’s important that food is heated evenly throughout. A carousel helps heat distribution; otherwise, you?ll need to rotate food 90 degrees at least once during cooking. Stirring food once or twice during cooking also helps eliminate cold spots in which bacteria can survive. Once cooked, it’s also important to allow food to stand for one to two minutes to allow for heat distribution. These same rules of stirring and standing apply when reheating leftovers. Heat till leftovers are bubbling hot; don’t just rely on the ?reheat? button.
EN’s Bottom Line. Food cooked in microwaves is safe to eat if cooked properly. Know the wattage of your oven and cook according to package instructions, including stirring, rotating and observing standing times.