Why Mayo-Based Casseroles Should Never Be Frozen

The freezer is one of modern technology's greatest strengths. It's an excellent way to avoid food waste, prepare meals ahead of time, and always have a ready-made dish on hand in a pinch. While freezing foods is common practice, not everything holds up well in such cold temperatures. Some foods, including mayonnaise, don't maintain their texture when frozen, so the defrosted result is sub-par compared to the original dish. If you ever plan on freezing a casserole you've made with mayo, you might want to think twice unless you're prepared for a pretty ugly result.

Casseroles are great make-ahead meals when they're loaded with things like tomato sauce, but if you're adding a lot of mayo to one, that mayonnaise will almost certainly separate as it defrosts. Mayo is made by emulsifying eggs and oil, and in a refrigerated or room-temperature state, that mayo holds up fine. But when it's frozen, ice crystals are formed. When those ice crystals defrost alongside the emulsion, they mess with the cell walls, causing the eggs and mayo to separate. The end result is a curdled-looking type of mayo — one that, while safe to eat, is a lot less appealing.

There is somewhat of a workaround: You can freeze everything but the mayo, then add it in later. Mayonnaise could be hiding in your store-bought salad dressing, so read the ingredients before making any sort of casserole featuring a creamy dressing. Or, if you're making anything where mayonnaise is the star (for example, a spinach and artichoke casserole likely contains a blend of cream cheese and mayo), you can still get most of it ready ahead of time.

Prepare the pasta, meat, vegetables, and any other freezer-friendly ingredients ahead of time. Then, freeze everything in an airtight container or dish the same way you would if it were fully prepared. When it comes time to defrost it, that's when you can make the mayo mixture that's likely holding the casserole together. While this doesn't work when you need a meal in a pinch, it's a good alternative for if you're planning ahead for a holiday or party. You can still buy all of the ingredients at once and prepare most of it ahead of time, then just build the casserole when you're ready to bake and serve it.