Microwaving Foods Does Not Kill All BacteriaOct 7, 2008 | Parker Waichman LLP Yesterday we reported on a link between 32 cases of salmonella poisoning in 12 states LINKED TO improper cooking of frozen food products such as chicken cordon blue and chicken breast Kiev. According to the United States Department of Agriculture’s (USDA) Food Safety and Inspection Service (FSIS), the entrees appear to be precooked and seem to only require microwaving before consumption; however, cooking the food in the microwave may not be sufficient to kill the bacteria. According to the FSIS, "It is especially important to use a food thermometer to check the internal temperature of these chicken products such that all points of measurement are at least 165° F.”
The recent, multi-state salmonella outbreak associated with undercooked chicken entrees is just the latest in a series of outbreaks related to the consumption of improperly microwaved frozen foods, says the AP. “Given how people use microwaves, it’s great for reheating, but maybe not so good for cooking,” said Doug Powell, scientific director of the International Food Safety Network based at Kansas State University.
Here’s the problem according to the AP report, microwaves heat unevenly, leaving cold spots in food that allow dangerous bacteria, such as E. coli, salmonella, or listeria, to breed. So, microwaving anything that includes raw meat—frozen or thawed—can lead to problems. “I think most food-safety experts probably would have said it’s not a good idea to microwave anything that’s from a raw state,” said Michael Davidson, a University of Tennessee food microbiologist. Microwaves operate by emitting short radio waves that penetrate food about one inch and stimulate the water, fat, and sugar molecules to produce heat; however, experts say this heats food unevenly.
“Many people wrongly assume all frozen meals are precooked and only need to be warmed; it’s a misconception fostered in part by foods prepared to appear cooked, such as chicken that has been breaded or pre-browned,” reported the AP. Actually, some meals meant for microwaving can be unsafe if not heated correctly or cooked using directions meant for a microwave with different voltage.
The government doesn’t track microwave-related food-borne illnesses, says the AP, which added that over 325,000 people are hospitalized for food-related illnesses annually with hundreds falling ill when Banquet pot pies made by ConAgra Foods were linked to salmonella and frozen pizzas made by General Mills were linked to E. coli last year. Both products were recalled. Since the recalls, food companies changed cooking instructions on frozen foods to ensure such instructions are appropriate for killing all dangerous bacteria, says Leslie Sarasin, head of the American Frozen Food Institute trade group. ConAgra and Nestle Prepared Foods, two of the largest frozen foods producers, have issued revised instructions on many of their brands, including Stouffer’s, Lean Cuisine, Banquet, and Healthy Choice.
In the recent outbreak, some of the meals were microwaved despite that the products were not meant for cooking in a microwave. Regardless, experts suggest using a food thermometer to check the temperature of microwaved food in a variety of places, especially if raw ingredients are included.