The U.S. Department of Agriculture’s (USDA) Food Safety and Inspection Service (FSIS) issued a public health alert on October 3, 2008 because 32 people in 12 different states seemed to have contracted Salmonella from eating raw, frozen, breaded, stuffed, and pre-browned chicken products such as Chicken Cordon Bleu and Chicken Breast Kiev that they had cooked in a microwave oven.
The FSIS noted that the chicken products carried instructions that they were raw, and there was no mention in the instructions that the products could be microwaved. However, the people who became ill from eating these products ignored the package directions, and cooked the chicken in the microwave as though it were a pre-cooked item that only needed reheating.
While the microwave oven can be a useful tool in any cook’s arsenal, to use it effectively you must understand its limitations. The microwave process relies on high heat that results from transforming electric current into short radio waves that are transmitted at a frequency of 2450 Megahertz. What this means is that cooking food on high in a microwave causes it to cook so quickly that heat only penetrates the food being cooked to a depth of 1 to 1.5 inches.
In thicker pieces of food, like large cuts of meat, the microwave doesn’t reach the center, leaving it raw. If you want to cook thicker pieces of food in a microwave, you should do so by using medium power, and allowing the food to cook for longer periods of time.
In this way, heat will reach the center without overcooking the outer edges. Another important limitation to be aware of is a microwave’s ability to destroy bacteria during cooking.
A microwave oven does destroy bacteria as long as the food is brought to the recommended internal temperature level that is considered safe. The problem arises because microwave cooking is less even than cooking in a traditional oven, making it possible that sections of the food being cooked haven’t reached the correct internal temperature. That’s why it is necessary to use a thermometer to test the food in several areas to see that all parts have reached the point at which bacteria has been destroyed. Here are the temperatures the USDA recommends:
- All ground meats — 160 degrees Fahrenheit
- All poultry — 165 degrees Fahrenheit (minimum)
- All cuts of pork — 160 degrees Fahrenheit
- Beef, veal, lamb steaks, chops, and roasts — 145 degrees Fahrenheit
- Eggs, and casseroles containing eggs — 160 degrees Fahrenheit
- Fish — 145 degrees Fahrenheit
The Department of Agriculture has also put together these tips to help you cook food more evenly in your microwave:
- Arrange food items evenly in a dish and add liquid if necessary. If possible, de-bone large pieces of meat because bones prevent heat from penetrating.
- Cover the dish with plastic wrap. Allow enough space between the food and the plastic wrap so that the plastic doesn’t touch the food. Poke vent holes in the wrap to allow steam to escape. This will create moist heat that will kill bacteria and ensure even cooking.
- Stir food midway through the cooking process to eliminate cold spots where bacteria can survive. Don’t rely on the microwave’s turntable; stir the food from top to bottom by hand.
- Follow the cooking instructions on the package, or in the recipe. Start with the recommended lowest amount of time, and added more time as necessary to reach the recommended internal temperature.
- Observe the carryover cooking time principle: Food continues to cook even after it is out of the microwave. This is known as “carryover cooking”, “standing time” or “resting time”. During this time, the internal temperature of the food can rise several degrees. That’s why it is important to follow directions if they call for allowing the food to rest. Just be sure to use a thermometer designed for microwave cooking to check that the food has reached the correct temperature before serving. Remember to check the item in several places.
If you would like more tips about how to use your microwave safely, including how to thaw in the microwave, how to reheat cooked food, and what kinds of containers are safe to use, check out the USDA’s free booklet Microwave Ovens and Food Safety (PDF).
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