Eggs can be scrambled, poached and even frozen, but there's one thing they should not be in the vicinity of: empty eggshells. You probably already know some of the other commandments of food safety and egg handling, but if you've been putting eggshells back into the carton with whole eggs, it's time to think again.
Related: How to Tell If Eggs Are Bad
Why You Should Never Put Eggshells Back in the Carton
Even if the unused eggs in your carton are free of cracks, bacteria could be lurking on the inside and outside of an egg, so it's best to limit any potential exposure by tossing them after use.
"For anyone handling shell eggs while cooking or baking, we recommend that after cracking open an egg, they immediately discard the shell in a compost or waste bin, rather than placing the shells back into the carton," explains Jeanine Flaherty, vice president of food safety and quality assurance at Vital Farms. "The raw egg residue left on eggshells after cracking can host bacteria, so this helps prevent possible contamination in the fridge. You should also immediately wash your hands, any utensils, equipment and surface areas after coming in contact with raw egg," Flaherty says.
Can I Get Sick from Keeping Eggshells in the Carton?
Even clean and uncracked eggs can contain Salmonella bacteria, which can cause foodborne illness, so it's best to avoid keeping cracked eggshells in the carton. Though egg producers have safeguards in place, safe handling must continue once the eggs have left the store and entered your home.
"Since you cannot properly wash a carton containing cracked eggshells with exposed raw egg, we do not recommend placing shells back into the carton with unused eggs as a precautionary measure to prevent any possibility of contamination and illness," says Flaherty.
While shopping, always check to make sure your eggs are uncracked and have clean shells!
How to Store Eggs Properly
Eggs should be stored in their original packaging and situated in the coldest part of your refrigerator, typically the middle or bottom shelf, to maintain safety and quality. This makes it so the eggs are less likely to be exposed to warm temperature changes as you open and close the fridge door.
The Food and Drug Administration recommends storing your eggs at a temperature of 40 degrees Fahrenheit or lower, which can be checked with a refrigerator thermometer. Use them within three weeks of purchase for the best quality and results. As for cooked dishes like egg casserole, consume any leftovers within three to four days, while hard-boiled eggs should be enjoyed within one week after cooking.
Common Uses for Eggshells
Eggs are a hard-working protein, and that includes their shells! Did you know that you can use eggshells to sharpen your blender blades? And instead of tossing them in the trash, add them to your compost.
"I give the shells a quick wash and store them in a bucket until I get a good bit. Then I grind them up with a food processor. A coffee grinder works well too," says Lisa Bynum, blogger at The Cooking Bride. "Eggshells are loaded with nutrients that plants need, such as calcium, phosphorus and magnesium. But since eggshells take a long time to break down on their own, it's important to grind them up before adding them to the compost."
Are Egg Cartons Recyclable?
Not all egg cartons are recyclable yet, but many companies are moving in that direction—just look for that triangular symbol of arrows on the carton. Whether or not you can recycle your carton, you can definitely reuse it as long as there has been no contact with raw egg. Use it to organize loose screws and wall-hanging bits in your tool storage, or try flipping it into a planter for herb seedlings.
If you're in the habit of placing empty eggshells back in the carton with whole eggs, stop it. You must kick that habit. Salmonella and other bacteria sometimes found on eggshells can make you sick and contaminate the other eggs.
Now that you know what to do with cracked eggshells—toss them, compost them, sharpen your blender blades—try your hand at eggs with jammy yolks with this Slow-Cooked Egg recipe, or add a little spice to your morning breakfast with this recipe for Salsa Scrambled Eggs.