Reheating cold rice safely requires careful attention because cooked rice can sometimes harbor spores of Bacillus cereus, a bacterium commonly associated with improperly stored foods. These spores can survive cooking, and if rice is left at room temperature for too long, the bacteria may multiply and produce toxins.

One important point is that some of these toxins can be resistant to heat, meaning that simply reheating the rice until it is steaming hot may not always eliminate the risk. That is why proper storage immediately after cooking is just as important as reheating it correctly.

To reduce the risk of foodborne illness, leftover rice should be refrigerated in shallow containers within two hours of cooking, or within one hour when temperatures are above 90°F (32°C). Keeping the rice in smaller portions also allows it to cool more quickly and evenly before refrigeration.

For best safety, refrigerated rice should generally be eaten within three to four days and reheated thoroughly until it reaches at least 165°F (74°C) throughout. When in doubt about how long rice has been sitting out or how it was stored, it is safer to discard it rather than take the risk.