Mash freezes well when it has plenty of butter, cream or cheese in it. Plain, low-fat mash turns grainy and watery, because there is nothing holding the starch together.
Potato starch separates from water when frozen, which is what makes thawed mash grainy. Fat coats the starch and prevents that, so the richer the mash, the better it survives. This is one case where the thing that makes it taste better also makes it freeze better.
| Keeps for | Up to two months |
|---|---|
| Freezes well | Mash made with butter, cream, sour cream or cheese |
| Freezes badly | Plain mash made with water or skimmed milk |
| Portion into | Scoops on a tray, or a flat bag |
| Reheat with | A splash of cream or milk, low and slow |
How to freeze and reheat it
- Make the mash richer than usual if you know it is going in the freezer.
- Cool it completely before it goes anywhere near the freezer.
- Scoop portions onto a lined tray and freeze until firm, then bag them.
- Reheat from frozen in a covered dish at a low oven temperature, or gently in a pan.
- Stir in a splash of cream or milk and a knob of butter as it heats, which brings the texture back.
What happens when you get it wrong
- Grainy, separated mash. Not enough fat. Beat in warm cream and butter as it reheats and most of it recovers.
- Watery mash. Usually from a floury potato variety or from freezing it warm.
- Gluey mash. Over-beaten, either before freezing or during reheating. Fold rather than whip.
- A frozen block you cannot portion. Freeze in scoops rather than one container.
Freeze it as duchess potatoes, piped into rosettes on a tray, which freeze and reheat beautifully.
Leftover mash also makes excellent potato cakes, which freeze better than mash does.
Frequently asked questions
Can you freeze mashed potatoes?
Yes, for up to two months, as long as the mash is rich. Butter, cream or cheese coats the starch and stops it separating. Plain low-fat mash thaws grainy.
Why does frozen mash go grainy?
Starch and water separate during freezing. Fat prevents that, so mash made with plenty of butter or cream survives and plain mash does not.
How do you reheat frozen mashed potatoes?
From frozen, covered, in a low oven, or gently in a pan. Stir in a splash of warm cream or milk and some butter as it heats to restore the texture.
Can you fix grainy mash?
Mostly. Beat in warm cream and butter over low heat. It will not be quite as good as fresh, but it is perfectly good.
What potatoes freeze best as mash?
Waxier varieties hold together better. Very floury potatoes make lighter mash fresh but tend to turn watery after freezing.