Forty Litres of Custard That Missed the Window
Saturday, 15:10. Two commis have just turned out 40 L of vanilla crème pâtissière; the kettle probe read 84 °C when they stopped cooking. They divide it into four hotel pans 10 cm deep, cover each with film while still hot, and slide them into the walk-in, whose air temperature is 4 °C at the door and 6 °C at the back. At 18:40 the centre of the deepest pan reads 24 °C. The custard is scheduled to fill 600 éclairs for a Monday 08:00 delivery. Your blast chiller failed on Friday and will not be serviced until Tuesday; six shelves in the walk-in are free. The commis says not to worry because 'it was boiled, so it is sterile.' The kitchen's written cooling standard is the usual two-stage one: 57 °C to 21 °C within 2 hours, then 21 °C to 5 °C within a further 4 hours.
1. Apply the two-stage standard to these numbers and decide the fate of the 40 L. Give the reasoning you would put in writing.
Read the worked answer
Timeline: cooked and turned out at 15:10, centre reading 24 °C at 18:40 - that is 3 hours 30 minutes, and the centre has not yet reached the 21 °C first-stage target. The first stage allows 2 hours. The batch is already at least 1.5 hours outside the standard and has not completed stage one at all, so stage two (21 °C to 5 °C within 4 hours, six hours total) cannot be met either.
Decision: discard the 40 L. Do not re-boil it, do not 'finish cooling and use it for the éclairs.'
The reasoning for the written record:
- The hazard is not only live bacteria. Crème pâtissière is a cooked egg and starch product handled by hands, whisks and film; Staphylococcus aureus can be introduced after cooking and produce a heat-stable enterotoxin, and Bacillus cereus can survive in the starch fraction. Neither is destroyed by returning the custard to the kettle.
- Extended time between 5 °C and 57 °C is exactly the growth window, and 3.5 hours is well beyond what the standard permits.
- The covering is a practical contributor: film placed on hot custard in a 10 cm pan traps an insulating layer of warm air, and a deep pan cools by conduction through its walls only. The product was effectively never exposed to the 4 °C air.
Record the volume, the times, the temperature readings, the corrective action (discard), the estimated value, and who made the call. The 600 éclairs are a scheduling problem; serving temperature-abused custard is a business-ending problem. Then tell the customer honestly and re-plan Monday.
2. The éclairs still have to be filled for Monday. Redesign tonight's cooling so the remaining custard is compliant, using only what you have.
Read the worked answer
Assume the whole 40 L must be remade. With no blast chiller, cooling rate is the constraint, so attack it in two stages.
Stage one - take the heat out in the kettle:
- Cook in four batches of 10 L, not one 40 L batch. A smaller mass cools faster and can be moved before it has spent its budget.
- Stand the kettle in an ice bath (ice, water, salt) and stir with a sanitised paddle, not a ladle. This is what gets 84 °C down to about 21 °C in 30–40 minutes instead of hours.
- Use a probe, not the clock, for the decision to move to stage two.
Stage two - maximise surface in the walk-in: 4. Fill pans to no more than 3 cm deep and leave them uncovered until the custard is at 21 °C, then film directly on the surface. Uncovered hot pans in a walk-in are a hygiene risk, so place them on the top free shelf, away from anything open, and keep the door closed. 5. Do not stack pans and do not use the back of the walk-in: the air there reads 6 °C, which is itself above standard and needs a maintenance call and a log entry. Verify with a probe at 30-minute intervals and log every reading. 6. If any batch misses stage one, discard it and start again - do not carry it forward and hope.
Contingency: 40 L in 10 L batches is six or more hours of section time tonight. If the honest arithmetic says you cannot cool and fill safely before Monday 08:00, cut the order down or move the delivery time. Say so on Saturday night, not on Monday morning.
3. How do you respond to the commis's 'it was boiled' argument, and which records do you fix before the next inspection?
Read the worked answer
Address the belief directly and without contempt. 84 °C is not sterilisation - sterilisation is around 121 °C under pressure - and boiling at 100 °C would still not be enough, because the hazard is not solely vegetative cells. Three things survive a kettle: heat-resistant spores, pre-formed toxins (notably staphylococcal enterotoxin), and anything introduced after cooking by hands, whisks, thermometers and film. 'It was boiled' answers a question nobody asked. The question is 'what happened to it between 84 °C and 5 °C, and how do we know?'
Then make it concrete with their own pan: a covered 10 cm pan of custard in a 4 °C room has a cooling curve closer to an insulated box than to a shallow tray. Show them the numbers from tonight rather than arguing principle.
Records to fix before the next inspection:
- Cooling log - product, batch size, start time and temperature, stage-one and stage-two times and temperatures, initials, and a corrective-action column that was actually used tonight.
- Probe calibration log - ice-point check (0 °C in an ice-water slurry) at the start of each week and after any drop, with the adjustment recorded.
- Walk-in temperature log - the 6 °C reading at the rear is a deviation and needs an entry, a maintenance request and a follow-up temperature.
- Corrective-action record for the 40 L discard, tied by batch number to the cooling log.
Finally, rewrite the cooling standard as a one-page bench card with the pan depth, the ice bath, the intervals and the discard rule, and put the probe in the commis's hand tonight rather than leaving the standard in a folder.