Mashed potatoes can be refrigerated for about three to five days as long as they're stored correctly. This includes making sure the temperature isn't too high or too low when they are stored in the fridge, which can cause them to spoil faster or slower. If mashed potatoes develop a sour smell, they are likely to have gone bad and should be thrown out. Mashed potatoes that have been refrigerated can be reheated on the stovetop or in the microwave.
To reheat mashed potatoes on the stovetop, put them in a saucepan over low heat and stir occasionally until they are hot throughout and smooth. You can also reheat frozen mashed potatoes in the microwave by placing them in a bowl and microwaving in one-minute increments until they are warm.
To freeze mashed potatoes, let them cool down before placing them in a plastic freezer bag or in a freezer-safe container. Press out the air as much as possible to prevent freezer burn. Label the bags or containers with the date and contents so you can easily find them when it comes time to eat them again.
Frozen mashed potatoes can last up to 12 months as long as they are stored properly. Make sure that they are in an airtight container to keep them from contaminating other foods in the freezer with bacteria. They can be reheated on the stovetop, in the oven, or in the microwave. When reheating, be careful not to overcook the potatoes as this can lead to them becoming mushy and slimy.