You should not use brown paper bags in the microwave oven. It’s a dangerous practice.
You see the articles all across the internet telling you to toss out the store bought bagged microwave popcorn in favor of making your own in a brown paper bag. In fact, here’s a current listing: Microwave Popcorn: Homemade, Cheap, and Easy! The additional headline should also read: Dangerous!
GE warns against the practice in the microwave oven manufacturer’s owner manual:
“Do not pop popcorn in your microwave oven unless in a special microwave popcorn accessory or unless you use popcorn labeled for use in microwave ovens.” [General Electric]
The fact is, cooking anything in a brown paper bag that is not labeled ‘oven safe’ or ‘microwave safe’, is not a good idea. Here’s why.
Brown Paper Bags Can Ignite
Many paper bags are made from recycled products. These can contain ignitable items such as metal flecks that can cause arcing. [General Electric]
Microwaves convert electric energy to microwave radiation. When food is exposed to microwave radiation, it excites the liquid molecules insides the food producing thermal energy that cooks the food. Microwave radiation cannot penetrate metal. If the waves hit metal, they will bounce off causing arcing, which can ignite the paper.
Paper can also contain synthetic fibers such as nylon filaments, which can also ignite.
Brown Paper Bags Can Emit Toxic Fumes
Brown paper bags begin as sheets of paper that are further processed. For example, they must be folded and glued to produce a bag with a square bottom. Many bags are also printed with ink. Some recycled products, the glue, and the ink may produce toxic fumes when heated that can contaminate food. [USDA]
Brown Paper Bags Are Unsanitary
If not labeled for cooking, brown paper bags created for other purposes may not be sanitary, as they were not intended to come into direct contact with food or be used in the microwave. The FDA tests and sets requirements for non-food items that are intended for use in the microwave, such as plastic containers and plastic wrap, but has no such guidelines for brown paper bags.
“Cooking Safely in the Microwave.” USDA. N.p., n.d. Web. 1 Apr. 2014. <http://www.fsis.usda.gov/factsheets/Cooking_Safely_in_the_Microwave/index.asp>.
“Turkey: Alternate Routes to the Table.” USDA. N.p., n.d. Web. 1 Apr. 2014. <http://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/poultry-preparation/turkey-alternate-routes-to-the-table/CT_Index/!ut/p/a1/jZDbTsMwDIafhQewktJtYpdTJLR2rNU0DiE3k2HuQZQkSlygPD0FrkAbzL6y_P2y9QkjtDAWX9>.
“Convection/Microwave Oven Owner’s Manual.” General Electric. N.p., n.d. Web. 1 Apr. 2014. <http://products.geappliances.com/MarketingObjectRetrieval/Dispatcher?RequestType=PDF&Name=49-40480-1.pdf>.
“Kitchen Food Safety: Bags, Bottles & Beyond.” University of Nebraska-Lancaster County Extension. N.p., n.d. Web. 1 Apr. 2014. <http://lancaster.unl.edu/food/ftsep04.htm>.