An outbreak of Salmonella that sickened 44 people highlights the need for consumers to follow all directions when it comes to microwaving food — including letting food "stand" after cooking, according to a new investigation of the outbreak.
During the outbreak, which occurred in summer 2010, people in 18 states fell ill with a type of bacteria called Salmonella enterica. The outbreak was later linked with consumption of Marie Callender's frozen chicken-and-rice meals, which were subsequently recalled.
Most of the people who fell ill in the outbreak reported cooking their meal in the microwave, but not all of them let the meal stand for the recommended time in the microwave before they dug in, according to a recent report from the Centers for Disease Control and Prevention. [5 Things You Shouldn't Do with a Microwave Oven]
"Microwave standing time is part of the cooking process," the report said. "Consumers should not only follow instructions for microwaving, but should also allow the product to stand for the recommended time before consuming," the CDC said.
A common feature of foodborne-illness outbreaks linked with frozen meals is the misconception that these foods are ready to eat, and just need to be reheated, the CDC said. But often, microwave cooking is a "critical control point to ensure raw and uncooked ingredients ... reach a sufficient temperature to render them safe from microbial hazards," the report said.
To prevent future outbreaks, manufacturers should clearly label products as "not ready to eat," and provide step-by-step cooking instructions on frozen meals that account for variability in microwave wattage, the report said.
In addition, consumers should know the wattage of their microwave and carefully follow instructions on how to prepare their frozen meals, the report said.
The CDC also recommended using a food thermometer to ensure that frozen meals are fully cooked and that all components reach 165 degrees Fahrenheit (74 degrees Celsius).
The report was published in the Dec. 6 issue of the CDC's Morbidity and Mortality Weekly Report.
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Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.