As much as I love making things like custardy ice cream and macarons, it drives me slightly nuts that you're required to leave half the egg behind. I'll diligently pour the remaining egg whites or yolks into a sealed container, tuck it away in the fridge, and then franticly begin searching for recipes to use the remainder before they go bad.
So I'm answering the question I asked a long time ago when I first found myself in this predicament: Can you freeze leftover egg whites and yolks? The simple answer is yes!
How to Freeze Egg Whites and Yolks
Both egg whites and yolks can be frozen successfully for up to a year. The key is to treat them right from the time you freeze them to the time you thaw them and use them. Here's how to do it.
Freezing Egg Whites
Egg whites can be frozen as is. For the greatest flexibility, pour each one into separate compartments of an ice cube tray. Freeze until solid and then transfer the egg white cubes to a freezer-safe container or zip-top bag. That way you'll be able to reach for the exact amount you need.
To thaw, transfer the cubes to the refrigerator overnight. They'll lose a little of their foaming power after being frozen, but will beat to their best volume if they rest at room temperature for 30 minutes. Otherwise, they can and should be used right after they are thawed. Thawed egg whites are also best used in things you intend to cook, so leave them out of your cocktails.
Read more: 10 Ways to Use Up Leftover Egg Whites
Freezing Egg Yolks
Egg yolks need a little more TLC, as they can gel and become paste-like when frozen. To prevent this, mix a pinch of salt or about 1/3 teaspoon of sugar, depending on whether you plan to use them for savory or sweet recipes, into each egg yolk before freezing — this keeps the proteins in the yolk from thickening up. Like egg whites, they can be frozen individually in ice cube trays, then moved to a freezer-safe container or zip-top bag for storage. They'll also need to be thawed overnight in the refrigerator before using. Use them right after they are thawed in any recipe that calls for them.
Read more: 12 Ways to Use Up Leftover Egg Yolks