Is It Safe To Eat Meat in Bloated or Swollen Packaging?

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.