I have an unopened bag of dog treats that is puffed up like a balloon about to burst. And I’ve seen similar packages of swollen plastic wrap in the meat section at the grocery store. Though I know that some bags like potato chips are purposefully bloated with plenty of air to make sure they don’t get crushed, is that true of fresh foods like meat? Here’s what I found out from the experts.
Why Packaging Swells or Bloats
Perishable food like meats or cheeses is susceptible to spoilage from the growth of bacteria and mold when exposed to air. Sometimes manufacturers use what’s called modified atmospheric packaging, or MAP, to lessen the chance of spoilage and encourage freshness by changing the gas inside the package. And MAP does sometimes make the packaging bloat.
“If it is not done by the manufacturer as part of MAP packing, then the puffiness is the result of microbial action,” says Martin Bucknavage, an expert in food safety at the Penn State Department of Food Science. “We see this with the normal overwrap with Styrofoam trays used by grocers or in vacuum-packed products.”
Oxygen is the most likely culprit for spoilage in food packages. An oxygen-rich environment can cause food to go bad and lose its nutrients. When microorganisms grow, they emit a gas such as carbon dioxide which can cause the package to engorge.
“Much like humans, when bacteria eat, they create waste in the form of chemicals and gasses. In an enclosed space with no holes, that gas will accumulate and eventually lead to swelling,” says microbiologist Jason Tetro, host of the Super Awesome Science Show and author of The Germ Codeand The Germ Files. “In this case, you do not want to be opening the package because it will smell quite bad.”
Are Swollen Meat Packages Safe to Eat?
“Assuming the packaging has swollen due to the growth of microorganisms, it may still be safe to eat, although perhaps not a pleasant experience,” says Jacob Tuell, assistant professor of animal science/food science at Northwest Missouri State University, and member of the muscle foods division at the Institute of Food Technologists.
Take a look at similar packages, he suggests. If they’re equally puffy, then it’s likely on purpose. Tuell recommends looking for other signs of spoilage such as odd coloring, an “off” smell, or a slimy texture. If any of those accompany the swelling, then toss the meat.
“It can be tricky for consumers as the bacteria that cause foods to spoil usually do not cause foodborne illness, and vice versa,” he says. “Pathogenic bacteria that cause people to get sick typically thrive at warmer temperatures, so making sure meat is kept cold is critical.”
Then, when you prepare it, make sure you cook it to the minimum safe temperature recommended by the United States Department of Agriculture (USDA). That’s 165°F for chicken, 160°F for ground meats, and 145°F for steaks, chops, and roasts.
To err on the safe side, however, it’s best just to avoid buying and eating meat with unusually swollen packaging.
“If the puffiness is not done on purpose, but rather the result of microbial spoilage, we would say no, that it should not be eaten,” says Bucknavage. “At this point, there is sufficient spoilage.”
To keep meat from puffing up at home, make sure it’s refrigerated and that you use it quickly. If you won’t use it in a timely manner, then freeze it to keep it from becoming spoiled.