Cooking encyclopedia
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Food safety
Cooked rice and Bacillus cereus
Also called fried rice syndrome
Why leftover rice needs handling more carefully than most cooked food.
What it is
Cool cooked rice quickly โ ideally within an hour โ keep it refrigerated, use it within a day, and reheat it once until steaming hot all through. Do not hold it warm for hours and do not leave it out overnight.
Why it works
Bacillus cereus survives cooking as spores. Cooked rice left in the danger zone lets those spores germinate and produce a heat-stable toxin, and reheating destroys the bacteria while leaving the toxin intact. The illness is from the toxin, not the organism, which is why "I reheated it thoroughly" is not a defence.
When to use it
Every dish that keeps cooked rice, pasta or other cooked starch for later, including fried rice made from yesterday's.
What goes wrong
Leaving a pot of rice out to cool slowly; keeping a rice cooker on warm all day; reheating the same rice twice; judging it by smell, which tells you nothing about the toxin.
More on this shelf
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Cassava and cyanogenic glycosides
Why cassava must be processed before it is eaten, and why traditional methods are the safety step.
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Cooling cooked food safely
Getting hot food out of the danger zone quickly, which is harder than getting it in.
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Cross-contamination
How raw food makes cooked food unsafe, and the small habits that prevent it.
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Home canning and botulism
Why low-acid food in sealed jars needs a tested process, not a household one.
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Raw fish and parasites
What makes fish safe to eat raw, and what does not.
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Reheating leftovers
How hot, how often, and what will not be fixed by reheating.
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Safe internal temperatures
The internal temperatures published guidance gives for cooked food, and how to measure them.
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Thawing safely
The three safe ways to thaw frozen food, and the one everybody uses that is not.
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The temperature danger zone
The temperature range in which bacteria multiply fastest, and how long food may spend there.