Cooling 60 kg of rabbit stew for a Maltese wedding
A small catering kitchen in Mosta prepares 60 kg of rabbit stew (stuffat tal-fenek) for a wedding. Cooking finishes at 19:30 on Friday. The stew is divided into four 15 kg stainless pots and left in the yard to cool; the night-time ambient temperature is 28°C. At 23:00 the pots are carried into a domestic fridge that already holds prepared salads and desserts for Saturday. The fridge door is opened repeatedly during the night. On Saturday at 08:00 the stew is reheated in the same pots until it is 'steaming', then transferred to chafing dishes and held at 62–68°C until service at 13:00. The caterer has no cooling or reheating records, and the probe thermometer has a cracked screen and has never been calibrated. On Sunday, two guests report vomiting and abdominal cramps that began 10–14 hours after eating. An Environmental Health Officer visits on Monday and asks how the stew was cooled and reheated.
1. Explain why the cooling and reheating process was unsafe, using the times and temperatures given. What is the most likely cause of the guests' illness?
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Cooling. At 19:30 the stew is near boiling. Four 15 kg pots have a large thermal mass, and a 28°C yard provides no forced cooling. After 3.5 hours the centre of each pot is likely still well above 21°C, so the stew has spent hours in the danger zone of 5–63°C. Moving the pots into a fridge already full of salads and desserts makes things worse: a domestic fridge cannot remove that much heat quickly, and the hot pots raise the fridge temperature, putting the salads at risk too. Overnight the core may never reach 5°C.
Why this matters biologically. Spores of Clostridium perfringens and Bacillus cereus survive cooking. Slow cooling through the danger zone lets them germinate and multiply. Reheating 'until steaming' is not a control: steam can appear at 65–70°C, well below a verified core temperature of 75°C. Holding at 62–68°C is also borderline, because part of the holding period is below 63°C.
Likely cause. The 10–14 hour incubation period and the vomiting/cramps are consistent with Clostridium perfringens food poisoning from stew cooled slowly and then inadequately reheated. The cracked, uncalibrated probe means no temperature measurement in this kitchen can be trusted, so the caterer cannot demonstrate that any step was safe.
2. Set out the corrective actions the caterer must take for future large-batch stews, including cooling times, equipment and reheating/hot-holding limits.
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Cool quickly in two stages. The target is 63°C to 21°C within 2 hours, then 21°C to 5°C within a further 4 hours (6 hours total). To achieve this with 60 kg:
- Divide the stew into shallow pans no more than about 5 cm deep, or use several smaller containers rather than four 15 kg pots.
- Use an ice bath, stirring, or a blast chiller. If none is available, use sealed bags or pans in iced water and monitor the core.
- Do not put hot pots into a stocked fridge. Either cool first, or use a dedicated fridge with space and forced air.
- Label each container with the date, time cooling started and use-by date. Keep cooled stew at 5°C or below and use within the business's safe shelf life (commonly 3 days for cooked high-risk food, subject to local guidance).
Reheating and hot holding. Reheat to at least 75°C at the core, or an equivalent time/temperature such as 70°C for 2 minutes. Stir to avoid cold spots. Hold hot food at 63°C or above; check with a calibrated probe at least every 2 hours and record it. If the food falls below 63°C, reheat it to 75°C once, or discard it. Do not reheat the same batch repeatedly.
3. What records should be kept, and what should the caterer do with the remaining stew and with the cracked probe?
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Records. Keep a cooling log (date, batch, start and end times, temperatures at 2 hours and at the end of cooling, initials), a reheating log (core temperature and time), a hot-holding log (temperature every 2 hours), a fridge temperature log, a probe calibration log and a record of any corrective action. The records must be contemporaneous and readable; a retrospective note is weak evidence.
Remaining stew. The stew that was served is implicated in illness. Any leftover stew from the same batch should be withdrawn and discarded; it must not be served, frozen or given to staff. The caterer should tell the EHO what happened, provide the batch details and cooperate with any investigation.
Cracked probe. Stop using it immediately. A cracked screen and no calibration history mean it cannot be relied on. Replace it with a waterproof digital probe, calibrate it using ice-point (0°C) and boiling-point checks, and record the results. Until a working probe is available, the business cannot verify cooking, cooling or holding temperatures and should not produce high-risk foods that depend on those measurements.
Root cause. The real failure is the absence of a planned cooling procedure, not just a broken thermometer. The caterer should rewrite the method for large-batch cooking, train staff and verify the procedure on the next batch by actually measuring the core during cooling.