Here's why you need to be careful when eating reheated leftover rice

A nationwide survey of 2,000 Americans reveals that some 72% of us enjoy eating leftovers - though certain reheated foods are preferred over others. 79% of respondents said that soup was their favorite food to reheat, while pizza came in second at 63%, meat came in third at 62%, and pasta came in fourth at 60%. Rice rounded out the top five at 55%. 

As tasty as all of these and other reheated foods can be coming out of a microwave or toaster oven, some foods require extra caution in order to avoid exposure to foodborne illnesses caused by salmonella, norovirus or staphylococcus aureus. Rice is one such food because it comes with some conditions that make reheating it a bit riskier and trickier than other foods. 

Why are there concerns over reheating rice?

There are a few reasons why you need to be extra careful when reheating rice. The first couple are that rice has neutral pH levels and it holds more moisture than other foods - both of which are conducive to bacterial growth. Rice also contains spores of bacteria known as Bacillus cereus, which can survive cooking and multiply when at room temperature for extended periods of time. 

"This Bacillus cereus can cause vomiting and diarrhea," says Shelley Rael, a registered dietitian and nutritionist based in Albuquerque New Mexico. She explains that this bacterial growth usually occurs when one doesn't get rice refrigerated fast enough after preparing, when rice is kept in the fridge for too long (3-4 days should be your max, according to the The U.S. Department of Health & Human Services' Food Safety app), or when one fails to reheat rice properly. 

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"Reheating rice doesn't usually pose any outright danger, but there are risks associated with doing it incorrectly," says Jen Messer, a nutrition consultant and registered dietitian at Jen Messer Nutrition. 

How long should rice be left out before putting in the fridge?

In addition to avoiding leaving rice in the fridge longer than 3-4 days before eating, it's also important not to let rice sit out too long after preparing before eating or refrigerating it.

Rael says the maximum amount of time rice should be left out after preparing and before eating or refrigeration is 2 hours, but this should be cut in half if serving rice outdoors. During a warm summer picnic, for instance, outside temps can reach the mid 80s or 90s, which would make bacteria growth more likely if rice is sitting out on a serving table alongside other foods. In such conditions, it's best to keep your rice cooled down or to toss it in the garbage if it's been sitting out for longer than an hour. 

How to reheat rice

There are a couple of things to consider when it comes to reheating rice. One is about doing so safely while the other is about doing so in a way that helps it retain its original taste and fluffy texture. 

Messer says the best way to ensure that rice stays tasty and fluffy is to add a little bit of water or broth before reheating. Some people accomplish this by placing a single ice cube and a damp paper towel over a plate or bowl of rice before microwaving it for a minute or two. Some reheat their rice in the microwave alongside a mug of water so that the steam created by the boiling water moistens the rice. Rice can also be reheated in the oven by mixing in 2 tablespoons of water for every cup of rice, per one cooking website, then spreading it out across an oven-safe pan. The container can then be covered with tin foil and heated for 15-20 minutes. Following the same water-to-rice ratio and heating the rice over a stovetop can also work. 

No matter which method you follow, Rael says you need to ensure the rice reaches an internal temperature of at least 165°F (74°C) before eating it. "I like to use an instant-read thermometer to check for this temp," she says. 

Messer agrees that 165° is the temperature necessary "to kill any bacteria and to make the rice safe to eat." She also says it's important to stir the rice frequently while heating to ensure that there are no remaining cold spots.

"Once the rice has reached the desired temperature, remove it from the microwave, oven or stovetop and let it stand for a minute or two before serving," she advises. "And be sure to avoid reheating any rice more than once."