Value Village ／ Food & living
This answer is a draft. It stays unpublished until legal review and source verification are complete.
"Retained-heat cooking" (保温調理, hoon chōri), turning off the flame and letting the pot finish cooking in its own heat, spread in Japan as an energy-saving idea. Leaving curry or stew in the pot at room temperature and eating it the next day, however, is the classic route to Clostridium perfringens food poisoning, and the Ministry of Health, Labour and Welfare (MHLW) warns about it repeatedly.
| Item | Details | Source |
|---|---|---|
| Clostridium perfringens food poisoning | 20–30 outbreaks a year, 1,000–2,000 patients. Many patients per outbreak (catering, mass cooking) | MHLW food poisoning statistics |
| Foods involved | Curry, stew, simmered dishes, soup: made in bulk and left standing | Same |
| Growth temperature | About 12–50°C, fastest at 43–47°C. Multiplies at the bottom of the pot, where there is little oxygen | Same |
| Spores | Survive several hours at 100°C. Germinate and multiply as the food cools | Same |
| Countermeasures | Divide into small portions and cool quickly (to 20°C or below within 2 hours), then refrigerate. Reheat to 75°C or above, stirring the whole pot | Same |
[Verify] Check the outbreak numbers and temperatures against the MHLW's material on Clostridium perfringens and the latest year of the food poisoning statistics.
Curry left at room temperature is the classic case of Clostridium perfringens poisoning. Finish it the same day, or divide it into portions and refrigerate.
Spores survive heating, and some of the bacteria that have multiplied can survive reheating. Reheating is necessary, but not leaving it standing comes first.
The centre of a large pot takes hours to cool, and the bacteria multiply in the meantime. Divide it into shallow containers, or stand the pot in water to cool it.
Inside a thermal cooker, the food stays for a long time in the bacteria's growth range. Eat within a few hours, or refrigerate. Making it in the morning and keeping it warm until evening is not recommended.
Catering and restaurants dominate the statistics because each outbreak affects many people. At home, "stomach ache after eating yesterday's curry" is a common case; severe illness is rare but does occur.
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https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/kenkou_iryou/shokuhin/syokuchu/
https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/kenkou_iryou/shokuhin/syokuchu/04.html
https://www.maff.go.jp/j/syouan/seisaku/foodpoisoning/
⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.
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