The Top Five Myths about Microwave Cooking
MYTH 1: Microwaves make food radioactive.
Fact: Microwaves are a form of non-ionizing electromagnetic radiation used to detect speeding cars and to send telephone and television communications. But microwaves have relatively low energy and cannot make food radioactive. Consumers are most familiar with microwaves as a source of energy for heating food.
MYTH 2: Microwaves kill the bacteria in food.
Fact: The heat that microwaves generate — not the microwaves themselves — kill bacteria found inside or on the surfaces of foods. Microwaves cook food by heating water molecules within the food. Put another way, microwaves cause water molecules to vibrate, and this vibration produces friction, which converts the water into steam, which, in turn, heats and cooks food.
MYTH 3: Microwaved food is less nutritious than food cooked in a conventional oven.
Fact: When cooking in a microwave, the energy heats only the food, not the entire oven compartment. This rapid cooking may help microwaved food retain more vitamins and minerals than with other cooking methods. This is especially true when microwaving foods without added water.
MYTH 4: When food cooks unevenly in a microwave oven, it means the oven isn’t working.
Fact: Foods with irregular shapes or varying thickness can cook unevenly in a microwave oven, leaving cold spots. In addition to shape and thickness, packaging material affects heating. Glass, paper, ceramic, or plastic containers are used in microwave cooking because microwave energy passes through these materials, heating only the food. Packaging materials and containers only become hot when they absorb heat from food as it cooks.
MYTH 5: It’s safe to microwave food until partially done.
Fact: Sometimes microwaves are used to partially cook or thaw foods that are then finished on the grill or in the oven. But, to maximize safety, it’s important to complete the cooking process right away. Avoid transferring partially cooked microwaved foods — especially meats — to the refrigerator to finish cooking later. Even more important, don’t leave partially cooked foods on the counter for an extended period. The partial cooking process may warm food to the perfect growth temperature for bacteria. Be sure to always measure the temperature of foods with a thermometer to make sure they are fully cooked and safe to eat.
The USDA has established these safe cooking temperatures for foods cooked in a microwave oven, conventional oven, grill, or stovetop.
Beef, pork, lamb, and veal steaks, chops, and roasts: 145°F
Ground meats: 160°F
The USDA also advises allowing microwaved food to stand for three minutes (to allow the cooking process to complete) before checking the internal temperature with a food thermometer.
Barbara Ingham is a professor in the Department of Food Science and a food safety specialist with the Division of Extension. Her expertise includes consumer perceptions of food safety and health as well as safe meat and food processing systems.