Cooking science

Carryover cooking

Food does not stop cooking when it leaves the heat. Heat already in the outer layers keeps travelling inwards for several minutes, and for a large piece of meat that can be a difference of several degrees — enough to take it from perfect to overdone while it sits on the board.

Why it happens

Cooking heats food from the outside in. When you take it off the heat, the surface is far hotter than the centre, and heat always flows from hot to cold. So the outer layers continue giving up their heat to the interior until the whole thing evens out.

The surface starts cooling immediately, because it is losing heat to the room as well. The centre, which has nowhere to lose heat to except outward through already-hot flesh, keeps rising for a while before it starts falling.

How much it rises depends on size and how hot the surface got. A thin fillet from a moderate oven barely moves; a large joint seared hard and roasted at high heat can rise substantially. This is why the instruction to take meat out below the target temperature is not optional for anything large.

Roughly how much to expect

Indicative rather than precise — it depends on the shape, the cooking temperature and the room.

Thin fillet, steak or chop

A degree or two. Barely matters.

Chicken breast or a small joint

A few degrees. Worth accounting for.

A whole chicken or a medium roast

Noticeably more, over ten to fifteen minutes.

A large joint or a turkey

Substantial, over half an hour or more. This is where people most often overshoot.

Anything cooked at very high heat

More carryover than the same thing cooked low, because the surface-to-centre difference is larger.

Sous vide

Almost none, because the surface was never hotter than the target.

What it means in practice

• Take large joints out early. How early depends on the size — the bigger the piece, the further below the target.
• Rest meat. Ten minutes for a steak, twenty to forty for a joint. It is doing two things at once: letting the carryover finish, and letting the tightened fibres relax and reabsorb liquid.
• Take scrambled eggs off underdone. They finish in the pan's residual heat in seconds, and this is the single most common carryover failure.
• Take custard off the heat before it looks thick enough, and pour it straight into a cold bowl. A hot pan will curdle a finished custard.
• Undercook vegetables slightly if they will sit, or refresh them in iced water to stop it entirely.
• Take fish off while the centre is still slightly translucent.
• Take a cake out when a skewer has a few moist crumbs on it, not when it is bone dry.

Resting, and the two things it does

The usual explanation for resting meat is that the juices "redistribute". That is broadly right — the muscle fibres contract under heat and squeeze liquid towards the centre and out; as they cool slightly they relax and hold on to more of it, so a rested steak loses far less onto the board when cut.

The less-discussed half is the carryover. Resting is also the period in which the interior finishes cooking, which is precisely why the meat came off the heat before it was done.

Rest uncovered or loosely tented. Wrapping tightly in foil traps steam against the surface and softens any crust you worked to build, which is a real cost on anything roasted or seared.

Common questions