The rice reheat risk
Dry rice can carry Bacillus cereus spores, tough dormant cells that survive boiling. Let cooked rice cool slowly and sit warm, and the spores wake up and multiply. Some strains make a toxin.
Cool rice fast and refrigerate it
Spread hot rice in a shallow tray so it cools fast, and refrigerate it within about an hour. Reheat only once, until steaming hot at 74°C (165°F). The toxin some strains make survives heat, so reheating can't rescue rice that sat out.
Test yourself
Questions from the interactive lesson, with the answer and the why.
Why is cooked rice left out overnight riskier than many foods?
Surviving spores can grow as it sits warm. Spores wake up in warm cooked rice and multiply.
True or false: Bacillus cereus spores can survive the boiling of rice.
True. The spores are heat-resistant, so normal cooking doesn't destroy them.
What went wrong? You make rice at 6 pm, leave the pot on the counter overnight, then reheat it piping hot. It still makes someone sick.
Hours at room temperature let spores multiply. Spores multiply at room temperature, and reheating may not destroy the toxin.
Fill the blank: Cooked rice should cool quickly and be kept ___ until reheated.
Cooked rice should cool quickly and be kept in the fridge until reheated. Cold slows growth, so refrigerate it soon.
Which situation is the classic Bacillus cereus food-poisoning risk?
Cooked rice left warm for hours. Spores grow as cooked rice sits at warm temperatures.
