Three Hundred Profiteroles That Collapse
A pastry section must produce 300 profiteroles for a christening on Sunday. On Saturday at 07:00 the commis makes choux paste with 1 L water, 400 g butter, 500 g bread flour and 16 eggs, pipes 4 cm rounds onto trays and bakes them at 190 °C on fan for 22 minutes, opening the door at 15 minutes to check, and rotating the trays. The buns come out golden, but as they cool about half slump into flat discs with a damp, doughy core. The pastry cream, made with 1 L milk, 200 g sugar, 80 g cornflour and 6 yolks, was cooked until it looked thick, then poured into a deep 20 cm pot, covered while hot and refrigerated. It is now lumpy and tastes of raw starch. The event is tomorrow and the section has flour, butter, eggs, milk and time, but no second oven.
1. Give at least three distinct causes for the collapse, with the mechanism behind each and the correction, and say which you think is the main one here.
Read the worked answer
1. The paste is too slack - the main cause. The classic ratio behind 1 L water and 400 g butter is about 600 g flour, not 500 g. With 500 g flour and 16 eggs (roughly 800 g of egg), the dough carries far more liquid than the flour can hold. Too much water means too much steam, the shell inflates before the structure sets, and when it cools the thin walls cannot support themselves. Correction: bring the flour up to about 600 g for that quantity of liquid, or add the eggs gradually and stop when the paste forms a soft peak that holds a V on the beater.
2. The panade was not dried enough. The flour must be cooked in the pan until it gelatinises and a film forms on the base - a minute or two of stirring over heat after it comes together. Under-cooked panade holds free water rather than bound water, giving a doughy core and weak walls.
3. The oven door was opened at 15 minutes. The buns rise on steam; releasing it before the protein and starch structure has set deflates them, and the temperature drop stalls the set. Correction: keep the door shut for at least 25 minutes, then check one bun.
4. Not pierced and cooled in a draught. As they cool, steam condenses inside; piercing each bun with a small knife and leaving them in the switched-off oven with the door ajar equalises it.
Under-baking is the usual partner to all of these: golden is not the same as dry and hollow inside.
2. Diagnose the pastry cream - why is it lumpy and why does it taste of raw starch? - and show how to salvage the batch.
Read the worked answer
Both symptoms point to the same fault: it was pulled off the heat when it merely looked thick. Starch thickening begins well below boiling, but full gelatinisation and the loss of the raw, pasty taste need the mixture to reach a boil and be held there briefly, about a minute, while whisking. Stopped early, the starch granules are only partly swollen, the cream is unstable and it tastes of flour.
The lumps come from uneven heating and from starch settling: cornflour added dry or a pot heated without constant whisking to the corners and base lets granules clump and gelatinise around each other. A deep pot of hot cream also cools very slowly in the middle, so it sits warm for hours - a genuine food-safety concern with egg and milk, as well as a texture problem.
Salvage: pass the batch through a fine sieve or tamis while still warm to break the lumps, return it to a clean pan with a splash of milk, and bring it back to a boil, whisking constantly, for one minute. Taste it: the raw note should be gone. Then cool it properly - spread in a shallow tray, cover with film touching the surface to prevent a skin, and chill quickly (blast chiller if free). If it still tastes of starch, more cooking will not fix it; start again, which costs 1 L of milk.
For tomorrow: bring it back to room temperature and beat it smooth before piping, and keep the filled profiteroles cold and assemble as close to service as possible, because choux softens within a couple of hours.
3. You have one oven, one day and 300 profiteroles to produce. Set out the production plan and the acceptance checks that stop a second failure.
Read the worked answer
Plan backwards from the event and use the oven in full batches.
Formula check first. Recalculate before mixing again: keep the 1 L water and 400 g butter, take the flour to about 600 g, and add the eggs gradually, assessing the paste rather than counting them, because egg size and flour dryness vary. Aim for a paste that falls from the beater in a slow V.
Batch and bake. One oven means the trays must not be overloaded and the door stays shut. Pipe at 4 cm, leaving room to double, bake at 190 °C fan for 25–28 minutes, then drop to 170 °C for a further 5–8 minutes to dry the interior. Then switch off, pierce each bun and leave them in the residual heat with the door ajar to dry. Work out the number of trays per hour from one test batch, not from optimism.
Acceptance checks. Cut one bun from every batch: it must be hollow with a dry interior and no doughy core, and it must still hold its shape five minutes after coming out. If a batch fails the cut test, stop and fix the paste rather than baking 300 of the wrong thing. Record the batch number and time.
Assembly and hold. Fill close to service only, keep them refrigerated and out of the humid area, and hold a reserve of unfilled shells. For 300 guests, bake around 340 shells so that breakages and failures do not force a last-minute substitution.