Gluey mashed potato

What has actually happened

A potato cell is a bag of starch granules. Cooked gently, those granules swell and the cells separate cleanly, giving a fluffy mash of intact cells.

Worked too hard — and particularly by a blade — the cell walls rupture and the swollen starch is released into the liquid. Free starch in water is glue. That is not a metaphor: it is the same mechanism that thickens a sauce, working against you.

Once the starch is out it cannot be put back. There is no ingredient and no technique that reverses it, which is why this page is mostly about prevention.

What is causing it

• A food processor or blender. The single worst thing you can do to a potato. Blades shear the cells open in seconds.
• A stick blender, for the same reason.
• Over-mashing or over-beating, even by hand. Mash until just smooth and stop.
• The wrong potato. Waxy varieties have smaller, denser cells and go gluey far more readily than floury ones.
• Mashing them wet. Water left in the pan is what the free starch turns to glue in. Drain thoroughly and dry them off.
• Adding cold butter or milk, which makes the mixture stiff and tempts you to beat it harder.

Making mash that is not gluey

1. Choose a floury potato — Maris Piper, King Edward, Rooster, Russet. Not Charlotte, Jersey Royals or anything sold as salad potatoes.
2. Cut them into even pieces so they cook at the same rate, and start them in cold water so they cook evenly rather than overcooking outside.
3. Simmer rather than boil hard. A rolling boil knocks them about and starts breaking cells before you have touched them.
4. Drain thoroughly, then return them to the dry pan over a low heat for a minute to steam off the surface water.
5. Use a ricer or a mouli if you have one. A masher is fine. A fork is fine. A blade is not.
6. Warm the milk or cream and soften the butter before they go in, so the mash does not need working to combine.
7. Fold gently, season, and stop. Every extra stroke is a risk.

What to do with gluey mash

It cannot be fixed, but it need not be wasted.

Potato cakes or farls

Gluey mash holds together beautifully. Shape, flour and fry.

A topping

Spread over a cottage or fish pie, forked and baked, where the texture is disguised.

Gnocchi

Poor choice — gnocchi needs dry fluffy potato and gluey mash gives heavy dumplings.

Thickening a soup

A spoonful works, since glue is what you want there.

Starting again

Sometimes the honest answer. Potatoes are cheap.

Common questions