Microwavable foods present a danger to consumers if the foods are not properly cooked. Risks include the transmission of foodborne pathogens such as E. coli 0157:H7 and Salmonella. In 2007 two foodborne outbreaks were associated with foods that were microwaved: an E. coli outbreak linked to Jeno’s and Totino’s frozen pizzas and a Salmonella outbreak linked to Banquet Pot Pies. Below are efforts by the food industry to address the issue of microwave safety. Note that these efforts do not address the problem of E. coli and Salmonella contamination in food processing plants. Although it is important for consumers to be educated as to the correct use of microwave ovens, consumers need to know that food manufacturers and others are liable for contamination of food products with E. coli and Salmonella, meaning consumers who are sickened by their food should be compensated regardless of how consumers cook the food product.

To address this issue, organizations such as the American Frozen Food Institute (AFFI) have been working to ensure consumers are properly cooking their food. AFFI put out a guide called “Cooking with Microwave Ovens, Nutrition and Food Safety Considerations” which shows readers how to prepare nutritious and safe meals using their microwave oven. The AFFI is also working with various organizations to make sure the labels of microwavable products have more information to account for varying power ratings and options on different microwaves.

The Grocery Manufacturers Association is also working microwavable food labels to ensure that cooking instructions on labels are valid, especially among not-ready-to-eat (NRTE) products. The validation of cooking instructions lets consumers know that following the instructions will ensure that their food has been properly prepared and has eliminated the risk of foodborne pathogens in NRTE products.

The need to validate cooking instructions comes from the problem of microwaves to unevenly heat food. Uneven cooking allows for hot and cold spots in the food and is ineffective at inactivating foodborne pathogens in the cold spots.

The International Assocation for Food Protection released a series of presentations that address the risks of microwavable foods. The presentations address a variety of areas that affect uneven heating:

Non-uniform distribution of dipolar molecules and ionic materials within the food.
Differences in microwave absorption of frozen/thawed areas.
Product/component edge heating effects.
Areas of high and low microwave field strength within the oven cavity and product.
Different food component and thermal properties.

All of the compiled information allows consumers to see the bigger picture when it comes to safely preparing microwavable foods. More testing and adequate labeling will allow consumer to know what they need to do to make sure that the food they prepare in microwaves is safe to eat.

Labels: E. coli, microwave safety, Salmonella