While most chefs advocate for making them fresh, mashed potatoes can be made ahead and frozen until ready to use.
The answer is yes—and it's easier than you might think to do it. Just whip up your favorite mashed potatoes, let them cool completely, then store them in a freezer bag, freezer-safe storage container, or a tightly covered, freezer-safe casserole dish and pop it in the freezer.
The most important thing to remember is the fat content (the milk, butter, or oil), so long as there's enough fat in the mashed potatoes, they will freeze well and will taste delicious when thawed and reheated (more on this below!)
Schmidt tells us that, for best results, you can keep mashed potatoes in "a freezer set to 0°F or colder" for "up to one year." At this temperature and for this length of time, frozen mashed potatoes can be thawed and reheated without losing texture or flavor (and without risking the transmission of foodborne bacteria) ...
Place frozen or thawed potatoes in a covered oven-safe dish and heat in a 350º F oven for 20 to 30 minutes, stirring occasionally, until heated through.
Restaurants prepare the potatoes ahead by boiling and mashing just the potato, then just before serving, it is mixed into boiling cream (or milk or even broth or a combination thereof) to reheat it and make it nice and creamy.
The reason behind this is that potatoes have a very high water content which means they don't freeze well and can turn soggy, watery, and potentially gritty once thawed. In fact, if you freeze raw potatoes, each drop of water will crystallize.
After defrosting them they are watery. That's pretty normal for frozen and re-heated mashed potatoes, just cook them a bit longer to drive off some excess moisture. They will tighten up.
Mashed potatoes(Cooked and refrigerated) will last 3 to 4 days. Raw potatoes(cut and stored in water) will last almost 24 hrs. Boiled(Cooked and refrigerated) will last 3-4 days.
Mashed potatoes, like other starchy dishes that are made with dairy (think: creamy casseroles, macaroni and cheese, scalloped potatoes), can develop a dry, gluey texture when reheated for too long, or at a temperature that's too high.
4 Ways to Reheat Mashed Potatoes. The reason mashed potatoes are so difficult to reheat has to do with their starch content. The amylose starch in potatoes reacts one of two ways when heated.
Microwave. The microwave is a more ideal method if you are reheating single-serve portions rather than a large batch of mashed potatoes. Plus, you'll need to let them thaw if they were frozen. Place your mashed potatoes into a microwave-safe container and heat them for 2 minutes.
Just transfer the mashed potatoes from the freezer to the fridge the night before you plan to use them. When you wake up, they'll be thawed and ready to reheat (gently and over low-medium heat). If you don't have the time, you can also thaw them on the stove.
You can use what you have on hand: Flour, cornstarch, or powdered milk are all solid options that are probably already in your pantry. For what it's worth, we recommend sticking with cornstarch—it has twice the thickening power of flour and it's safe for gluten-free diets.
Too much whipping (or mashing) will give you sticky — not fluffy — mashed potatoes. Make the best of it and turn them into cheesy mashed potato cups: Mix the potatoes with grated cheddar and an egg, then scoop the mixture into lightly greased muffin cups.
When too much starch gets released, the potatoes become gummy, gluey, and unappetizing. Overworking the potatoes can happen in a couple ways: either by simply handling them too much, or by using a food processor, blender, or similar tool, which mixes the potatoes too aggressively.
Some cells will inevitably burst, releasing tacky gel that helps give mashed potatoes their cohesiveness. But if too much gelled starch seeps out of the cells, either from overcooking or too-vigorous mashing (or both), gumminess ensues.
Lay the potato on a tray without letting them touch each other. Pop the tray into the freezer and, when frozen solid (about six to 12 hours), transfer to a resealable airtight freezer bag, remove any excess air, label and pop back into the freezer.
This process, which is called oxidation, happens because potatoes are a naturally starchy vegetable. And when exposed to oxygen, starches turn gray, brown, or even black. An oxidized potato is completely safe to eat. The process doesn't affect the flavor or texture of the vegetable.
Because you just put them into the freezer, the cell structure hasn't broken down so while the visual looks bad, they are probably still safe to eat.
Make-ahead mashed potatoes are a great option for the holidays. You can do nearly everything — boil, peel, and mash; stir in milk and salt — up to two days ahead. Before serving, reheat. Adding butter at the last minute makes them taste freshly mashed.
If mashed potatoes are on the menu — and oh, we hope they are! — you may have wondered if you can shave off some party-day stress by making them ahead of time. We've got good news: You can prep the potatoes themselves a few days beforehand — and actually mash them up to 1 day before.
As soon as you peel the potatoes, you'll want to place them into a bowl of water so they're fully submerged, and then store the bowl of potatoes and water in the refrigerator. The water will seal off the potatoes from the air, so the chemical reaction can't occur. Pretty smart.