What It Really Means When Your Canned Food Makes A 'Hissing' Sound

Canned food is one of the most affordable ways to shop for groceries without sacrificing nutrients. According to the Can Manufacturers Institute, canned vegetables cost substantially less than their fresh or frozen counterparts — up to 50% less than frozen and 20% less than fresh. The best part? The nutrients are almost perfectly preserved, so you can still get the vitamins and minerals that come from those vegetables.

Besides being affordable, canned food is also a great way to preserve food for long periods of time. You might have noticed that some of the canned items you purchase at your local store have expiration dates that are several years into the future. This is great for situations where refrigeration isn't possible, such as a power outage. It's also useful for places like food pantries, where foods may be stored for a while.

Though canned food has its perks, there are also a few risk factors to be made aware of, such as why cans make hissing sounds — and when that sound might indicate a spoiled product.

Why does canned food sometimes hiss?

If you've ever opened a can of food and noticed a hissing sound, you're not alone — and it's not always a cause for concern. According to the U.S. Department of Agriculture, canned foods sometimes release a hiss when opened simply because they are pressurized when prepared. In that case, the food is perfectly safe to eat.

However, the USDA warns that if the canned food "hisses loudly" or the contents "spurt forcefully out of the can" upon opening it, it's a sign that the food has not been properly stored. If either of these occur when opening a can, the food should not be tasted or touched. Rather, it should be immediately thrown away.

The USDA also notes that when canned goods have not been properly pressurized and sealed, they can also potentially carry botulism spores. This is quite rare, but can cause serious illness or even death in anyone who consumes these goods, so if your can's hiss sounds amiss, it may be better to stay on the safe side.