Leftover rice doesn't seem like a dangerous dish, but this staple is actually vulnerable to contamination that can lead to food poisoning. Reheating rice does not necessarily remove all the danger; proper storage is the only way to prevent bacterial growth. Safe storage of cooked rice requires prompt packaging and a strict time limit.
Pathogens in Rice
The most dangerous pathogen in rice is a type of bacteria called Bacillus cereus. This microorganism's spores are resistant to heat, meaning that they can survive cooking. As the rice cools to room temperature, the spores produce new bacteria, which in turn produce toxins. These toxins can cause diarrhea, cramps and nausea. Although unpleasant, these symptoms are seldom dangerous and usually go away after about 24 hours. People with weakened immune systems may be at risk, however.
Over time, cooked rice stored in a refrigerator can visibly go bad. It may dry out, change color or texture or begin to smell. However, even rice that appears perfectly normal may contain B. cereus spores or bacteria. Don't rely on the appearance of rice to indicate safety. The only reliable way to keep cooked rice safe is to store it quickly and keep it refrigerated.
Because B. cereus can grow and develop quickly, serve rice immediately after cooking. If you find you've made too much, package the leftovers in an airtight container and refrigerate them as soon as possible. Refrigerated foods should be kept below 40 degrees; above this point is the "danger zone," in which bacterial growth occurs rapidly.
To speed up cooling, spread the rice as thinly as possible in a shallow dish; don't worry about it being perfectly room temperature before putting in the refrigerator. If rice has been sitting at room temperature on the table or in the kitchen for a few hours, throw it out rather than refrigerating it.
Reheating Cooked Rice
When reheating cooked rice, be sure that it is heated all the way through. Turn over the rice with a fork to reach the center of the dish; the center, as well as the surface, should be steaming hot. Cooked rice can last up to 3 or 4 days when refrigerated, but to minimize the chance of food poisoning you should heat it within 1 day of refrigerating it.
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