Why does bread go hard? The answer is the starch

August 2, 2026

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The bread was soft yesterday and hard today. Most people assume it has dried out. Usually that is not what has happened.

Short answer: Bread goes hard because the starch inside it recrystallises after baking. The technical word is retrogradation. In everyday speech we just say the bread has gone stale. The process runs fastest at fridge temperature, which is why bread in the fridge goes hard sooner than bread left on the worktop.

Hard and dry are two different things

Dry bread has lost water. The water has evaporated into the room air, and it does not come back on its own.

Hard bread has often lost no water at all. The water is still in there, but it no longer sits where it sat when the bread was fresh. That is why a hard slice can turn soft again after a few minutes in the oven, while a slice that really has dried out only gets warm and hard.

The simplest test is the weight. A loaf that has stood out and gone hard weighs much the same as it did coming out of the oven. It has not dried, it has set.

How the starch settles back

Flour is mostly starch. During baking the starch granules soak up water and swell. They go from hard grains to a soft, jelly-like mass, and it is that mass that makes fresh crumb tender.

As soon as the bread cools, the starch works its way back towards the firm form it had before. The molecules line up again, and the crystals that form are hard. At the same time some of the water is pushed out of the starch and over towards the crust.

The crumb turns firm and crumbly, even though the bread still holds almost as much water as before.

Why it happens fastest in the fridge

The speed is governed by temperature, and not in the way most people think. The process runs fastest between 0 and 8 °C, which is exactly where your fridge sits.

Place	Temperature	What happens to the starch
Freezer	Around minus 18 °C	Almost a full stop, the water is locked up as ice
Worktop	18 to 22 °C	Steady, but slow
Fridge	0 to 8 °C	Faster than anywhere else

A loaf in the fridge can go as hard in one day as a loaf on the worktop does in three. The whole explanation is in the article on storing bread in the fridge. The freezer does the opposite, because there the water is locked up as ice. If the bread has to last for weeks, freezing is the right answer, see the guide on freezing bread properly.

The crust and the crumb go different ways

Straight out of the oven the crust is dry and crisp, while the crumb is moist. That difference wants to even itself out, so the moisture travels from the inside out.

Two things therefore happen at once in the same loaf: the crust turns softer and chewier, and the crumb turns firmer. Wrap the bread completely tight and the moisture gathers under the crust and the loaf goes limp. Leave it lying open and the moisture escapes altogether, and then the bread is dry as well as hard.

The answer lies in between. Bread should sit in something that breathes. A bag in cotton and linen coated with beeswax holds the moisture in the crumb without smothering the crust, and the clip closes the bag without making it airtight. With a baguette the balance is even more obvious, see the guide on keeping a baguette crisp.

Heat turns the clock back, for a while

The crystals that make bread hard melt when they are warmed. At around 50 to 60 °C they dissolve, the starch turns soft again, and the bread behaves almost as if it were freshly baked.

That is why a few minutes in the oven rescues a hard slice, and why toast tastes fresh. But the effect is borrowed. As the bread cools down again the crystals form once more, and now it goes faster, because a little water was lost along the way.

The rule is simple: only reheat what you are going to eat straight away. Take the bread out of the bag first, because the bag must never go in the oven. The methods with water, oven and steam are in the guide on reviving dry bread.

Five habits that keep bread soft for longer

1
Let the bread go completely cold before you wrap it
A lukewarm loaf steams. Steam that gets shut in gives you a soggy crust and a risk of mould.
2
Cut only what you are eating now
Every new cut surface lets moisture out. Stand the loaf cut side down on the board between meals.
3
Keep the bread at room temperature
The worktop, not the fridge. And in something that breathes, not in sealed plastic.
4
Freeze the rest the same day
Slice the loaf first. Freeze it while it is fresh, not once it has already gone hard.
5
Choose a coarser loaf when you want it to keep
Wholemeal and rye bread hold on to water better than a white loaf, so they go hard more slowly.

The type of grain matters more than most people think. There is more about that in the article on wholemeal and rye bread.

Frequently asked questions

Why does bread go hard so quickly?

Because the process starts the moment the bread begins to cool. A white loaf often feels different the day after baking, while coarser bread with more moisture takes longer.

Does bread go hard faster in the fridge?

Yes. Fridge temperature is precisely the range where the starch crystallises fastest. If the bread has to keep for a long time, it belongs in the freezer, not in the fridge.

Can I eat bread that has gone hard?

Yes. Hard bread is not spoiled, only set. It is mould that makes bread unsafe, not the hardness. Hard bread is lovely in the oven, in soup or as croutons.

Does it help to wrap the bread in a plastic bag?

The crumb stays soft a little longer, but the crust turns soft and chewy, and the damp air inside the bag brings mould on sooner. A material that breathes is the better compromise.