Cooking regime

Wet heat under pressure

Every other wet method is capped by the boiling point of water. A sealed pressure cooker raises that cap by raising the pressure inside it, and the resulting increase in temperature cuts cooking times dramatically.

Why sealing the pot changes the physics

Water boils when its vapour pressure matches the pressure pushing down on it. Increase that pressure and the water has to get hotter before it can boil.

A sealed pot traps the steam it produces, the pressure rises, and the water inside reaches a temperature meaningfully above ordinary boiling point. Cooking rates rise steeply with temperature, so the effect on time is much larger than the temperature difference suggests.

It is the only wet method that escapes the ceiling, and that single fact is what makes it useful. Everything else about it — the sealing, the venting, the caution — follows from the pressure it needs to do it.

What it changes

Time

Dramatically shorter. Long braises, stocks, pulses and tough cuts take a fraction of the usual time.

Tough cuts

Collagen converts to gelatine much faster, so shin, cheek and oxtail become tender quickly.

Dried pulses

Cooked from dry in a manageable time, which is the single most useful thing it does.

Stock

A rich stock in an hour rather than several, and clearer, because there is no agitation.

Evaporation

Almost none, because the pot is sealed. Sauces do not reduce and need less liquid than a normal recipe.

Aroma

Volatile compounds are retained rather than lost — sometimes an advantage, sometimes a muddiness.

Browning

Still impossible inside. Brown before sealing, in the same pot.

What it does not do

• It does not brown. The interior is wet and the surface stays wet. Sear first, in the pot, before sealing.
• It does not reduce. Nothing evaporates, so a sauce that would have thickened will not. Reduce afterwards with the lid off.
• It does not let you taste as you go, which is a real loss. Season conservatively and adjust at the end.
• It does not suit delicate food. Fish, eggs and green vegetables overcook in the time it takes to come up to pressure.
• It does not develop slow-cooked flavour in quite the same way. A pressure-cooked braise is tender faster and tastes slightly less deep.
• It does not make safety judgements for you. Whether a food is safely cooked is a matter for a food safety authority rather than for a description of how the heat arrives. In the UK the Food Standards Agency sets that guidance and it is the one to follow.
• It does not replace a normal pot — it is a specialist that happens to be very good at three or four jobs.

Using one well

1. Brown everything first, in the open pot, exactly as you would for a normal braise. This is the step people skip and it is the one that matters.
2. Deglaze thoroughly. Anything stuck to the base can scorch under pressure and will trigger a burn warning on an electric model.
3. Use noticeably less liquid than a conventional recipe, because none will evaporate. Enough to generate steam and no more.
4. Do not overfill. Every manufacturer states a maximum, and foods that foam — pulses, grains, pasta — need a lower one.
5. Bring it to pressure, then turn the heat down to the minimum that maintains it. More heat achieves nothing.
6. Time from the moment pressure is reached, not from when it went on the heat.
7. Release pressure the way the dish wants — quickly for anything that would overcook, naturally for meat and pulses.
8. Open it, taste, and reduce or adjust with the lid off. Almost every pressure-cooked dish needs finishing.

Common questions