Microwave ovens do not cook food like other appliances. In a regular oven, hot air makes both the food and its container hot, while in a microwave, the air is cool. The microwave oven emits microwaves which cause food molecules to vibrate. The resulting friction causes heat. This heat can get hot enough to kill the bacteria in foods. However, there are a few limitations.
These microwaves mainly heat the molecules on the outside of the food. This can, in turn, heat further inside the food, but usually there are cold spots. These cold spots are uncooked or unheated food where bacteria can survive. But, there are some things you can do to prepare food safely and deliciously in a microwave.
These guidelines are important whether you are cooking raw food or reheating a meal.
It is important to become familiar with your microwave. Different ovens will take longer to cook the same food. All foods should be cooked right away after defrosting. Never partially cook food and store it for later use.
Be especially careful when heating baby formula in a microwave, as it may result in a scald to the baby's mouth or throat. Even though a bottle might not feel warm to the touch after it has been microwaved briefly, there may be hot spots within the formula. Microwave heating is not advised for warming or thawing breast milk. The excess heat can destroy proteins and other nutrients.
It is important to cook food in a container that will not melt. If the container melts, harmful chemicals can leak into the food.
Use cookware made of:
Plastic wraps are commonly used to cover food while cooking in a microwave. Some wraps have chemicals that would be harmful if they leaked into the food. Precautions should be taken to make sure that the plastic wrap does not touch the food at all. Never reuse plastic wrap. Alternatively, a paper towel or a lid for a microwave-safe container might be the safest way to go.
Microwaves themselves do not destroy nutrients. However, heat can cause the nutrient level in foods to be reduced. Water can dissolve and wash away some vitamins. This is true of any type of cooking. There has been some speculation that microwaved food can be harmful to people. There is no credible experimental evidence to back up that statement.
Eat Right—Academy of Nutrition and Dietetics
Food Safety and Inspection Service—United States Department of Agriculture
Canadian Partnership for Consumer Food Safety Education
Cooking meat safely. Clemson University Cooperative Extension Service website. Available at: http://www.clemson.edu/extension/hgic/food/food_safety/handling/hgic3580.html. Updated June 2011. Accessed February 14, 2017.
Cooking safely in the microwave oven. United States Department of Agriculture website. Available at: http://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/appliances-and-thermometers/cooking-safely-in-the-microwave/cooking-safely-in-the-microwave-oven. Updated August 8, 2013. Accessed February 14, 2017.
Dietary guidelines for Americans 2010. US Department of Agriculture and US Department of Health and Human Services. Available at: http://www.health.gov/dietaryguidelines/dga2010/DietaryGuidelines2010.pdf. Accessed February 14, 2017.
Microwave cooking and nutrition. The Harvard Medical School Family Health Guide website. Available at: http://www.health.harvard.edu/staying-healthy/microwave-cooking-and-nutrition. Updated January 2015. Accessed February 14, 2017.
Microwave ovens and food safety. United States Department of Agriculture website. Available at: http://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/appliances-and-thermometers/microwave-ovens-and-food-safety/ct_index. Updated August 8, 2013. Accessed February 14, 2017.
Storing and preparing expressed breast milk. American Academy of Pediatrics Healthy Children website. Available at: http://www.healthychildren.org/English/ages-stages/baby/breastfeeding/Pages/Storing-and-Preparing-Expressed-Breast-Milk.aspx. Updated September 9, 2016. Accessed February 14, 2017.
Last reviewed February 2017 by Michael Woods, MD, FAAP Last Updated: 3/6/2015