Cooked rice left at room temperature for too long can become a happy home to intruders. Photo / Karsten Moran, The New York Times
Cooked rice left at room temperature for too long can become a happy home to intruders. Photo / Karsten Moran, The New York Times
Simple, common-sense guidelines to avoid getting sick.
If the social media rumours are true, your leftover rice may be trying to kill you. Experts on the matter, however, tell a somewhat different story.
It’s true that cooked rice left at room temperature too long can becomea happy home to intruders, notably Bacillus cereus, a common type of bacteria that lives in soil and, therefore, in much of the food we eat. “B. cereus loves to grow in the warm and moist environment provided by cooked rice,” said Si Ming Man, a professor in the division of immunology and infectious diseases at the Australian National University.
What has made B. cereus more TikTok-famous than other food-borne bugs is that its spores are hardy enough to survive the cooking process, and then - when food isn’t kept cool in the refrigerator - can grow and produce toxins that even vigorous reheating won’t destroy, Man said. And yes, while the illness is sometimes referred to as “reheated rice syndrome”, since leftover rice is a common pathway, other foods (steak, pasta salad, milkshakes) have prompted B. cereus outbreaks. (The case that recently went viral on TikTok was caused by spaghetti left at room temperature for five days in 2008 - definitely don’t do that.)
So what about the countless batches of leftovers you’ve zapped (or even eaten cold) over the years without a trip to the hospital? Martin Wiedmann, a food safety professor at Cornell University, said the reason we hear relatively little about those cases is because “the disease is typically very mild, unlike other food-borne diseases”. Symptoms show up in one of two unpleasant ways - primarily vomiting or diarrhoea - but both usually resolve on their own within 24 hours.
“The illness is likely to be over by the time you are inspired to do something about it,” said Linda J. Harris, a professor at the University of California, Davis, who researches microbial food safety. “The exception,” she added, “is for those people who might have weakened immune systems” - children younger than 5, adults aged 65 and older, and pregnant and other immunocompromised people. But experts agree even healthy people have good reason to follow the simple, common-sense guidelines below.
How long does rice last in the fridge?
The US Department of Health and Human Services gives us four to six days to eat cooked rice (and up to four days for most other leftovers), so long as it’s been stored in a fridge that’s 4C or cooler, and never left out for more than two hours (or at most one hour on particularly hot days). Some experts go with a more conservative four-day maximum and recommend reheating no more than once, since more trips out of the fridge mean more time spent in the danger zone.
It may take a little trial and error, but steaming rice in the microwave can yield great results. Photo / Julia Gartland, The New York Times
Can you freeze rice?
In the freezer, cooked rice will keep for up to six months, per the US Department of Health and Human Services, but limiting its stay to under two months will help keep it fresher. Andrea Nguyen, who wrote Ever-Green Vietnamese, recommends freezing rice in any airtight container you’d use to refrigerate it. “I don’t keep rice frozen for long so there’s no need to get fussy and complicated,” she said. Thaw it in the fridge, then reheat it as above, or toss it directly into simmering soups and stews.
For evenly cooked grains without the chance of scorching a pot, Priya Krishna, who reported on this very subject in the New York Times last year, recommends steaming rice in the microwave: Rinse the rice well and add it to a large microwave-safe bowl, along with twice the volume of water. Microwave it uncovered for 15 to 25 minutes, depending on the strength of your microwave (finding your exact timing may take a little trial and error). As the rice plumps and water simmers away, the microwave captures the steam, much like a lidded pot. (Pro tip: There is also no better time to wipe down the inside of your microwave.)
How do you reheat rice?
To warm up cold rice and recover much of its fluffy texture, Michael W. Twitty, author of Rice: A Savour the South Cookbook, likes to heat it in a skillet with a little liquid and oil, or another fat “until it’s spongy and steamy again”. Nguyen takes a similar approach, or just uses the microwave, sprinkling on a bit of water then loosely covering and using high power. Both methods restore much-needed moisture to grains that tend to dry out significantly in the fridge.
Kimchi fried rice is a stellar and simple way to use up leftover rice on a weeknight. Photo / Con Poulos, The New York Times
How can I put leftover rice to use?
Cookbook author Julie Sahni’s go-to breakfast is fried eggs nestled in zucchini or spinach stir-fried with leftover rice, cumin, garlic, chilis and coriander, sometimes topped with roasted seaweed flakes or crushed potato chips.
To his fried rice, Twitty adds bits of pastrami or kosher surimi - for example, imitation shrimp or crab, as in California rolls and sushi bakes - in the manner of Carolina crab fried rice.
These days, Nguyen packs her fried rice with vegetables: “Like a 1:1 ratio,” she said. “Vegetable fried rice seldom has enough vegetables.”
