What Does It Mean If Your Canned Food Makes A Hissing Sound?

There's no denying that canned foods are an essential staple of kitchen pantries everywhere. Whether it's canned tuna for an easy tuna salad lunch, canned soup for a rainy day, or canned tomatoes to make your favorite comfort food recipes, canned foods are an affordable, nutritious, and time-saving option for busy families. Chances are, you have a few cans of food laying around your pantry right now.

Canned foods are also handy to have around because they have such a long shelf life. According to the USDA, depending on how acidic the contents are, canned goods will maintain their best quality from 18 months up to five years. Stored properly, canned foods in good condition are safe to consume indefinitely. What does it mean for a can to be in good condition? You probably already know to avoid eating from a dented can, since cans with severe dents, including cracks and broken seals, or dents along a seam, could be contaminated with Clostridium botulinum, a dangerous bacteria that could cause severe illness or even death. What if the can makes a hissing sound when you open it? Are the contents still safe to eat?

Canned foods are vacuum-sealed during the canning process to keep out harmful microorganisms, a process that can involve vacuum packing or using heat to create the vacuum, explains Britannica. According to the USDA, cans that were vacuum packed can make a hissing sound when they are opened — the noise is due to the air pressure and "is perfectly normal." In other words, it's perfectly safe to eat the food in those cans.

However, the USDA goes on to warn that there are certain situations where canned food should not be consumed. If the hissing sound is loud, or the contents of the can "spurt forcefully out," then there is a good chance that the food has spoiled and is no longer safe to eat. Consumers are warned not to eat or to even taste the food from any such cans. Other signs of spoilage that consumers should be aware of include rusty, bulging, or leaking cans, or any food that smells off, the Canned Food Information Council explained to the Los Angeles Times. All such cans should be thrown away in a closed garbage bag and properly disposed of in the trash container or landfill.