Vol. XV · Dry Heat Plate 6 of 11roasting, oven temperature, roast beef, hot and fast, low and slow, grey band, juiciness, carryover, resting, thermometerHT

Roasting.

The same 8 cm joint takes under an hour and a half at 230 °C and nearly three hours at 120 °C. The slow one is pink almost to the edge.

A roast is too thick for a pan: its centre would never cook before the outside burned. The oven surrounds it with hot air and radiating walls (II.7) and lets heat creep inward for an hour or more. The choice is the oven temperature. Hot and fast — 220–230 °C — browns well and is quick, but the outside races ahead of the centre, leaving a thick band of grey, drier meat, more juice lost and a big carryover rise (II.9). Low and slow — 110–140 °C — heats more evenly: the meat is the same doneness nearly to the edge and loses less juice, but browns little and takes much longer.

Cooks combine them: a short blast of high heat at the start or the end for the crust (XV.7), with most of the cooking at a lower temperature. Whatever the oven, the thermometer in the centre, not the clock, decides when it comes out (I.4), and the roast rests before carving while its temperature evens out. The workshop roasts a joint.

Below: an 80 mm beef joint roasted to 52 °C at the centre and rested 20 minutes, at the oven temperature you choose (thermal bench): time, cross-section of the highest temperatures reached, grey band, juice lost and browning, compared across ovens.

What you will learn

Compare hot-and-fast with low-and-slow roasting.
Relate oven temperature to grey band and juice loss.
Use a thermometer and resting.
Choose an oven temperature for a cut.

Workshop

Thermal bench: beef, 80 mm slab, from 5 °C, in an oven with wall radiation (h 12 W/m² K), roasted until the centre reaches 52 °C, then rested 20 minutes. Grey band: depth of meat whose highest temperature passed 62 °C. Juice loss from the course loss curve; browning on the course teaching scale.

Hot crust or even pink

In this model the 80 mm joint takes 2 h 47 min at 120 °C and 80 min at 230 °C. The slow roast has a grey band of about 26 mm in total; the fast one, 80 mm — most of the joint. The fast roast browns well; the slow one barely browns at all, which is why the best of both is a slow roast finished with a short, very hot blast or a sear (XV.7).

Practical roasting. Take the joint out of the fridge an hour ahead only if it is small; salt it well ahead (VIII.2); put it on a rack so air reaches all sides; use a probe thermometer and pull it 5–10 °C below the target, more for a hot oven (II.9); rest it loosely covered for 15–30 minutes. Tender cuts (rib, sirloin, loin, leg of lamb) roast well; tough cuts need moist heat (XVI.4). For poultry, whose breast and legs want different temperatures, see XVIII.7.

At the stove

Roast two small identical joints, one at 230 °C and one at 130 °C, to the same centre temperature. Slice both and compare the band of grey meat under the crust.

In English the word "roast" once meant cooking on a spit before an open fire; what most kitchens now do in an oven was historically called baking, and the old distinction survives in the phrase "spit-roast".

Terms

Roasting: Cooking a large piece in the dry heat of an oven.
Hot and fast: Roasting at 220–230 °C: quick, brown, with a thick grey band.
Low and slow: Roasting at 110–140 °C: even, pink to the edge, little browning.
Probe thermometer: A thermometer left in the meat in the oven.

A hot oven browns and is quick but leaves a thick grey band; a low oven cooks evenly but pale. Combine them, and cook to temperature, not time.

Sources

A teaching value chosen for the course: the right order of magnitude and shape, not a measurement of a particular food.
H. McGee, On Food and Cooking: The Science and Lore of the Kitchen, 2nd ed., Scribner, 2004.