Cooling the Curry
A hospital catering kitchen cooks 40 litres of chicken curry at 11:00 for the next day's lunch service. The cook decants it into four shallow stainless pans, each about 10 cm deep, and places them on a bench in the prep area to cool 'so they don't warm the fridge up'. The prep area is 24°C. At 15:00 the cook checks with a probe and finds the curry at 32°C in the centre of one pan. She moves the pans into the walk-in chiller, which is at 5°C and already three-quarters full with other food. At 09:00 the next morning the curry is reheated in a large pan and served at 12:00. The kitchen's HACCP plan states cooling must reach 8°C within 90 minutes.
1. Assess the cooling process against the HACCP plan and explain the microbiological risk created by what actually happened.
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Against the plan: the curry sat at 24°C for four hours and was still at 32°C at 15:00. The plan requires 8°C within 90 minutes; the actual process took many hours and never met the standard before chilling. Placing hot pans in a full chiller also raises the chiller's air temperature and puts other stored food at risk - the chiller is not designed to absorb that heat load.
Microbiological risk: the danger zone is 5–63°C, and the range 20–50°C is where food-poisoning bacteria multiply fastest. Four hours at 24°C, falling only slowly to 32°C, gives Clostridium perfringens and Bacillus cereus ideal conditions. C. perfringens is the classic cooked-meat-and-gravy organism: it forms heat-resistant spores that survive cooking, then germinate and multiply during slow cooling. Reheating kills the vegetative cells but not the toxin already formed, so reheating does not make the food safe.
The curry is therefore a high-risk product that has been through a documented time/temperature abuse.
2. Recommend a corrected cooling method and the monitoring that must accompany it, including what to do if the target is missed.
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Corrected method (choose one or combine):
- Decant into shallow pans no more than 5 cm deep to increase surface area, and place in a blast chiller if available.
- Use an ice bath or cooling paddles to bring the temperature down quickly.
- Divide into smaller batches so the chiller is not overloaded; never place hot food in a full chiller with other ready-to-eat food.
- Target: 63°C to 8°C within 90 minutes (or the plan's stated time), then hold at 5°C or below.
Monitoring:
- Probe the centre of each batch with a calibrated, disinfected probe at the start, at 45 minutes, and at 90 minutes.
- Record batch, time, temperature, and initials on the cooling log.
- Verify the chiller is holding 5°C or below with a separate check.
If the target is missed: treat the food as unsafe. Do not serve it. Discard it or, if the plan allows and the time/temperature is within a defined safe limit, reheat to 75°C or above and use immediately - but where the limit has clearly been exceeded, discard. Record the incident and review the cooling procedure.
3. The cook argues that reheating to boiling the next day makes the curry safe. Explain why this is wrong.
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Reheating kills bacterial cells but does not destroy heat-stable toxins or spores already formed. Clostridium perfringens produces a toxin in the gut after ingestion of large numbers of cells; slow cooling allows those cells to multiply to high numbers, and reheating does not remove them all. Bacillus cereus forms heat-stable toxins in food. So the food can still cause illness after reheating.
The purpose of reheating is to reduce risk in food that has been correctly cooled and stored - it is not a rescue step for food that has been temperature-abused. The safety of the dish depends on the whole chain: cook, cool fast, store cold, reheat thoroughly. A failure at the cooling step cannot be corrected later. The correct action is to discard the affected batch and record the decision.