Microwave Food Safety

Traditionally, most people rely on cooking to kill harmful bacteria present in food. With regards to microwave ovens, some special precautions are necessary. Studies have shown that when certain foods (hot dogs, hamburgers, and tomato soup) were intentionally contaminated with bacteria, and then cooked two different ways, higher levels of bacteria survived microwaving than conventional cooking. Thus, thorough cooking of meats, poultry, and fish is necessary to prevent food borne illness.

The problem is that microwave cooking has a tendency to leave “cold spots” in food. Cold spots, or uneven cooking, can occur because of:

Cold spots are a problem more than just because unevenly heated food is unappetizing. When foods are heated unevenly, and some parts are left undercooked, it allows bacteria and other microorganisms to survive and flourish. As it is, more than 1/3 of marketed raw chickens are contaminated with Salmonella. Allowing Salmonella to grow and multiply because of undercooking is like asking for a bout with a food borne illness. As another example, undercooked pork has been known to cause illness because the microorganism Trichinella survived the cooking process.

In addition to the problem of cold spots inside a food, much of the moisture near the outside surface of the food evaporates during long microwave cooking times. This leaves the surface cooler than the inside. Because the air around the food never gets hot like traditional ovens do, bacteria on the surface of the food are more likely to survive the microwaving process.

To ensure the most even heating as possible, some standard microwave cooking techniques must be used. There are five important ways to minimize cold spots:

See Leader’s Guide Level A for a discussion of these techniques.

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