The Minnesota Department of Health (MDH) conducted a study looking at the types of food service establishments that use microwave ovens, how those ovens are used, the types of food cooked, and the level of compliance with U.S. FDA guidelines. Microwave ovens are good at reheating food, but can be a food safety hazard when used to cook foods such as meat, chicken, or eggs because of uneven heating or improper use.
MDH collected data from 60 food establishments in the state, including fast-food restaurants, sit-down restaurants, school food service, nursing homes, hotels, motels, and day care centers. The food prep was classified as pre-serve, cook serve, or complex.
Most of the establishments in this study reported using microwave ovens to warm commercial ready-to-eat products and to warm foods for palatability. No minimum temps are required for these foods because they do not require pathogen destruction (except when RTE foods are contaminated).
But, food establishments using complex preparation (stove top, microwave, plus oven) did use the microwave for processes that require heating to a temperature to kill pathogens. For those establishments, most managers reported following FDA recommendations for cooking and heating, but many did not let the food stand for 2 minutes on a solid surface, as required by the government, for the food to reach a safe final internal temperature. The study recommends that additional training be given to employees of these establishments.
The USDA offers information on cooking safely in a microwave oven that applies to consumer use too. Those rules state that large cuts of meat should not be cooked on high power, because the exterior could be overcooked by the time the interior reaches safe temperatures. Stirring or rotating food halfway through the cooking time can help eliminate cold spots where bacteria can survive and make someone side.
Food should never be partially cooked in a microwave and held to finish cooking in a conventional oven or on the grill. And standing time is important for cooking to complete. Let the food stand for 2 minutes before checking the final temperature with a reliable food thermometer. The food should stand on a solid surface, and not on a wire rack, so the heat doesn’t dissipate as it stands.