Can I eat it: what's this about not eating leftover rice??
March 25, 2022 1:04 PM   Subscribe

Possibly just the internet being a ninny, but some article went around the other day about someone having horrible medical problems after eating leftover rice and a few people were like yeah, I never do. Is this really a thing? Is there a real health risk there? I eat next-day rice all the time but since I read that, am reluctant. Somebody science me out of this?
posted by less-of-course to Food & Drink (28 answers total) 7 users marked this as a favorite
Best answer: Rice that is left at room temperature can harbor a bacteria that causes food poisoning. Cooking the rice will kill the bacteria but not the spores.

If you cook rice, immediately refrigerate, and reheat leftovers only once then you should be fine. If you make a big pot of rice that you heat and cool over and over, the cumulative time in the danger zone can increase the risk.
posted by muddgirl at 1:09 PM on March 25, 2022 [17 favorites]

The NHS says. Essentially what muddgirl said.
posted by Splunge at 1:11 PM on March 25, 2022 [1 favorite]

Cooks Illustrated says:
Rice of all types can be contaminated with the spore-forming bacteria called Bacillus cereus. Present but dormant in all raw brown and white rice varieties, the spores are not killed by the boiling cooking water—instead, they are actually revived and converted into potentially harmful live bacteria as the rice cools.

To play it safe, follow these guidelines from the USDA when storing and reheating leftover rice: - Do not leave rice sitting out for more than 1 hour before eating or refrigerating. - Reheat rice to 165 degrees as measured with a food thermometer. - Dispose of refrigerated rice after 3 to 4 days.
posted by fedward at 1:12 PM on March 25, 2022 [3 favorites]

I remember reading the same thing, but I've been eating leftover rice for forty years and I've never had a problem. I also spent a year as an exchange student in Japan, and regularly observed my host family leaving leftover rice at room temperature overnight to eat it the next day. Might this have terrible consequences for me some day? Maybe. But right now I'm not concerned.

(P.S. Don't forget the canieatit tag!)
posted by Faint of Butt at 1:12 PM on March 25, 2022 [18 favorites]

There are an estimated 63,000 cases of Bacillus cereus poisoning in the U.S. each year, surprisingly. It's also a problem in pasta. But yeah, if you store rice quickly and then heat it up sufficiently, you should be completely fine eating it the next day.
posted by pinochiette at 1:22 PM on March 25, 2022 [1 favorite]

In contrast to Fait of Butt's anecdote, my brother and his large extended Vietnamese family never leave rice out and always reheat well. He finally got our (white) parents to stop leaving rice out overnight by patiently explaining the risks of Bacillus cereus to them (the info wasn't legitimate when it came from me, but whatever makes them safer is great). There's no reason to play fast and loose with food safety rules!
posted by twelve cent archie at 1:25 PM on March 25, 2022 [5 favorites]

Anecdotally, I've experienced friends getting sick from leftover rice a couple of times (it was narrowed down due to other people eating other leftover elements besides the rice and being fine). Both occasions the experience apparently wasn't pleasant at all, to put it very mildly. I remember one friend who went through it said it was worse than the time she ate bad seafood.

YMMV if you want to roll the dice on something like that. For me personally it's not worth it, considering how easy it is to make rice fresh.
posted by fight or flight at 1:38 PM on March 25, 2022 [2 favorites]

FWIW I cook large portions of rice, then throw it in the fridge so I can scoop a few servings into in a bowl and nuke with other leftovers the next day, pretty much every week.

I suppose I don't leave the rice out room temp for longer than an hour, though I'm sure I have a few times by accident and never really gave it a second thought. And I never reheat the entire batch all at once. Didn't know any of this was a thing.
posted by windbox at 1:47 PM on March 25, 2022 [3 favorites]

Previously, previously. But I totally understand why this comes up repeatedly: It's intuitive that you don't leave out raw meat and fish, for example, but cooked rice seems like it would be safe. In fact, even though I'd read this before, I currently have some rice in the fridge that I left out for a few hours before cooling. Going to go toss it now...
posted by Mr.Know-it-some at 1:52 PM on March 25, 2022 [5 favorites]

Bacillus cereus spores survive boiling, but not pressure cooking at 15 lbs of pressure, and I’m not sure why, with the proliferation of instapots, we haven’t seen more emphasis on pressure cooking rice.

Maybe it’s a texture thing, or that it could be hard to get the timing just right — and that’s important because you can’t sample rice in a pressure cooker along the way to tell if it’s ready.

I’ve tried it a number of times with mixed results. It’s not that much of a time saver with white rice and there’s a significant danger of turniing your rice into mush.

But I only make brown rice these days, for which there is a big time savings. However, I also prefer basmati rice, and I’ve never quite convinced myself that the pressure cooker doesn’t tend to destroy the aroma.
posted by jamjam at 1:56 PM on March 25, 2022 [3 favorites]

Some models of Instantpots have a rice cooker setting, which does not get up to pressure-just a note for anyone coming to this thread later.
posted by warriorqueen at 2:26 PM on March 25, 2022 [4 favorites]

I don't know why rice specifically gets such a bad reputation for this as uncooked pasta also contains B. cereus spores. TBH I get a whiff of the same msg-aversion from this but ¯\_(ツ)_/¯

Just treat your leftover rice as you'd treat leftover pasta.
posted by blueberrypuffin at 2:31 PM on March 25, 2022 [6 favorites]

I eat leftover Chinese white rice all the time, unrefrigerated, 18 hours later. I don’t refrigerate it because it ruins the texture. Haven’t gotten sick once.
posted by Melismata at 2:54 PM on March 25, 2022 [4 favorites]

If you "cover" the rice, it should refrigerate fine for a day or two. Uncovered and unrefrigerated rice can get moldy or get "wet" and sour in a day or two, and you don't want that.

I sometimes leave rice in the rice cooker for a day or two, covered and closed, of course.
posted by kschang at 3:20 PM on March 25, 2022 [2 favorites]

I don't know why rice specifically gets such a bad reputation for this as uncooked pasta also contains B. cereus spores. TBH I get a whiff of the same msg-aversion from this but ¯\_(ツ)_/¯

Because rice is much more likely to contain the bacteria than pasta and rice is a much better environment for the bacteria than other starches:
Rice derivatives (boiled, fried), due to its composition and chemical characteristics, represent an excellent growth medium for bacteria and can support the growth of B. cereus at different temperature conditions. B. cereus spores can survive perfectly in the dehydrated rice, without loss of viability for at least 48 weeks of storage.
Note that this article also cites the fact that rice accounted for approximately 95% of cases of food poisoning across various studies compared to other sources (though you could argue that this is because it's generally more common, worldwide, to store partially cooked rice in unsafe conditions vs. cooked pasta). Still, it seems like the bacteria in general is just more common in rice.
posted by fight or flight at 3:30 PM on March 25, 2022 [9 favorites]

Just put leftovers in the fridge within a couple hours of cooking, and I think you'll be fine. Be watchful in humid weather, and if your rice smells at all weird, toss it. This is more of an issue with commercial kitchens, from my understanding. It's rarer for people to suffer issues from home cooking, assuming basic precautions. The person who will die from this kind of issue is more like that one unfortunate young man a couple years back, who consumed grains left out for something like five days.

Of course, you may have greater goals than the mere avoidance of death, but I can honestly say cold leftover rice and pasta has never made me sick, and I eat a LOT of it, because I prefer cold food most of the time, and don't have a microwave anyway. I also keep rice in the fridge far longer than the NHS recommendation of "one day" lmao damn I am a food criminal. If you're a stickler for safety, don't listen to me. But if my risk style sounds like yours, well, I've spent almost my whole lifetime consuming cold leftover rice and pasta multiple times a week. I have yet to become inexplicably ill, or dead.

But I do put leftovers away promptly, and would encourage others to do the same.
posted by desert outpost at 3:40 PM on March 25, 2022 [2 favorites]

the spores are not killed by the boiling cooking water—instead, they are actually revived and converted into potentially harmful live bacteria as the rice cools.

well that is horrifying.

but I've been eating leftover rice for forty years

I wonder if some people are just much less sensitive to it. Like if you eat a lot of starch you have a healthy gut microbiome and maybe it takes care of that bacteria. Or if you eat a lot of rice specifically you build up some kind of immunity.

It's just, if this were a thing I feel like Chinese people would be sick a lot. And a lot of other people who eat a lot of rice.
posted by Glinn at 4:17 PM on March 25, 2022 [7 favorites]

Yeah, another instance of Chinese food syndrome where there's one giant pot of rice made and served all day long, not much of a problem if it's kept appropriately warm. I sorta live off of 15 pound bags of rice and a smart cooker, still like everything leave it out a couple of hours to cool to room temperature before tossing it into the fridge. Or making a pot in the morning for breakfast, packing some in a sack for lunch and leaving the rest on keep-warm for dinner when I get home. No problems. It does get really nasty rather quickly if you forget about it, nasty orange spores or moldy looking or smelly. Mostly around here, it dries up into a brick rather quickly (dry climate). Definitely on the three or four days in the fridge spectrum before throwing out like 20 cents worth of rice instead of just making more.
posted by zengargoyle at 4:29 PM on March 25, 2022

I've gotten food poisoning from rice a couple of times. Both times I left the cooked rice on the stove, which was always slightly warm from the pilot light. (It took the second time getting sick for me to realize that prepping and storing rice like this was the cause, because the rice was the common factor in both food poisonings.) You're most likely to get sick if the rice is kept warm but not hot for an extended period, like in a situation where it's served at a buffet station over a sterno can. You cannot smell or taste or see cereus bacillus and the poisoning is caused by toxins excreted from it, so whether it's alive or dead or the rice passes a sniff test or you have a good immune system is irrelevant.
posted by phoenixy at 9:39 PM on March 25, 2022 [2 favorites]

This story about a student was reported on very inaccurately. A lot of places reported he had amputations because of food poisoning but it was actually meningitis.
posted by fiercekitten at 9:46 PM on March 25, 2022 [1 favorite]

pinochiette: "There are an estimated 63,000 cases of Bacillus cereus poisoning in the U.S. each year"
It's worth asking is this a big number? CDC estimates that there are 1,500,000 cases of Campylobacter and 1,350,000 cases of Salmonella poisoning in the USA annually. You could of course do neither a) wash your chicken in the kitchen sink [aerosol salad alert!] b) eat reheated rice.
posted by BobTheScientist at 12:38 AM on March 26, 2022 [3 favorites]

I treat cooked rice in the same way as other leftovers -- into the refrigerator in covered tupperware ASAP after cooking -- and I have never been sick. I am aware that rice is particularly risky (spores; large surface area) so I definitely never leave cooked rice standing around unrefrigerated and would throw it out if it happened by accident.

(I was in my thirties when I found out that there are people who think you can't reheat and/or refrigerate rice; I wonder if this is either a texture issue which leads people to leave cooked rice outside the fridge, or conversely a mutation of the belief that you can't eat leftover rice at all because it's unsafe. I don't understand this; I refrigerate and reheat rice all the time. It's not exactly the same as fresh, but it's fine.)
posted by confluency at 4:45 AM on March 26, 2022

The starches in cooked rice that is refrigerated undergo retrogradation, which permanently changes the texture of the rice. It is impossible for reheated rice to have the same texture as freshly cooked rice or rice that has never been chilled.
posted by slkinsey at 6:49 AM on March 26, 2022

I eat rice almost every day, and I cook a large batch in a Zojiruji rice cooker, then put it into a glass pyrex container and put it in the fridge when cooled, then eat off of it for up to 5 days by taking some out and reheating. Never had food poisoning in the hundreds to thousands of times I have done this. N=1, anecdata, blahblahblah.
posted by SinAesthetic at 8:42 AM on March 26, 2022 [1 favorite]

It is impossible for reheated rice to have the same texture as freshly cooked rice or rice that has never been chilled.

Which is why freshly cooked rice doesn’t work well in fried rice….that effect is a feature not a bug.
posted by koahiatamadl at 9:42 AM on March 26, 2022 [6 favorites]

For what it’s worth, I pressure cook my rice and it’s usually perfect. I’ve done it with long, short, and medium grain using the same recipe:

- Rinse 2-3 cups of rice and drain, add to instant pot
- Add equivalent (1:1) amount of water. Add butter/salt as desired for taste.
- pressure cook at high pressure for 4 minutes, let sit 10 minutes after it’s done before venting and opening the cooker
- fluff the rice after you open the pot
- that’s it!
posted by sleeping bear at 12:34 AM on March 27, 2022 [3 favorites]

Yeah, pressure cooked rice works well, but in my experience you must get the measurements and timing EXACTLY right for for the grain and texture you're aiming for. Any even small deviation can lead to pretty poor outcomes.
posted by flamk at 10:52 AM on March 27, 2022 [2 favorites]

Having had Bacillus cereus poisoning, I can tell you I have never been sicker in my entire life. I am scrupulous about food safety with rice now. Trust me when I say you don't want to take chances with this, especially for something as cheap as rice.
posted by fiercecupcake at 9:09 AM on March 28, 2022 [2 favorites]

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