Signs you can still eat food even if it's past its best-by date

• Expiration dates predict food quality, not when it will actually spoil.
• Use your senses to determine if you can eat food after the expiration date.
• Apps like FoodKeeper can help you calculate when to throw out old food.
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There are two types of people in this world: those who live by expiration dates, and those who chance it with the smell test.

For those who are tempted to chance it, the good news is that date doesn't always reflect your food's actual condition.

Many foods are OK to eat beyond their peak quality, as long as you know what to look for.

Here's what you really need to know about expiration dates, and how to judge if it's worth taking the risk.

What 'best by' really means

The "best by" date describes when your food is going to be at its best quality - not when it goes bad, said Elisabeth Anderson, director of science communication for the Center for Research on Ingredient Safety at Michigan State University.

The same goes for "use by" or "best if used by" dates. "Sell by" is a message for retailers to know how long to keep an item on the shelves, so that's typically even further from when food actually goes bad.

The only food that truly has an expiration date is infant formula, which contains important nutrients that could change over time. Formula should be thrown out immediately after it expires, Anderson said.

It passes a smell test

Just because a food is not technically expired doesn't mean it will taste good, Anderson said.

For instance, food frozen at 0°F technically never spoils to the point of being unsafe to eat. You can eat freezer-burned foods if you can get past the taste and texture, but the USDA recommends throwing out any frozen foods that develop a rancid odor.

It's even more important to use your senses when trying items that have been sitting in your fridge for a while.

"If it smells weird, don't drink it," Anderson said. Changes in color, consistency, and taste could also indicate it's time to throw out old food.

For instance, salad greens will turn slimy, brown, or yellow as they go bad. A rotten smell is a definite sign your leaves have turned.

There's no sign of mold

Mold is also a surefire sign to toss old fruit, bread, or dairy. You don't know what that organism is and whether it will upset your stomach, Anderson said.

A piece of fruit contaminated by mold should go straight to the trash, she added.

With bread, it might be tempting to throw out the moldy slice and eat the rest. But what looks like a small spot of mold could penetrate deeper into the loaf than the eye can see.

"Maybe if it's at the other end of the bag, I would chance it. But I wouldn't chance it with my child," Anderson said.

It's been stored in a cool, dry place

Food storage is an important factor in the spoiling process. Storing your food in a cool, dark, and dry environment will make it last longer compared to food left out on the counter in a sunny or humid kitchen.

Anderson recommended using the FoodKeeper app to consider how food is stored when determining shelf life.

On the app, you can compare timelines for freezing or refrigerating food versus storing it in the pantry. Eggs, for instance, last three to five weeks in the fridge after their purchase date.

It may be helpful to label your food with the date of when you bought it or the date to throw it out, Anderson said.

Especially with leftovers - which can last three or four days in the fridge if well-wrapped - it can give you some peace of mind to have the date set in Sharpie instead of guessing at it.