Is it safe to eat rice left in the rice cooker overnight?

May 16, 2022 1:34 PM

How long is it safe to leave cooked rice in a rice cooker before eating it? If there's rice left over from dinner, can I leave it in the cooker overnight and eat it for breakfast without risking food poisoning?

When I used an instant-read thermometer to check the temperature of some rice I'd forgotten about and left in the cooker overnight, it was above 150F.

I know that it's possible to refrigerate leftover rice and that it makes the best fried rice later; this is about whether it's safe to eat still-hot rice if it's been in the cooker for 12 hours or so.

posted by Lexica to Food & Drink (20 answers total)

Important clarification: do you have a keep warm setting on your rice cooker?
posted by chocotaco at 1:35 PM on May 16, 2022 [6 favorites]

We leave rice in the rice-cooker all the time. For one, it saves fridge space. And second, rice like all starches goes more stale in the fridge. That doesn't always matter.

I have never left it warm in the cooker overnight, though, I don't know if it is good or bad. Usually, we deliberately make enough rice so we can have fried rice for breakfast and there is no need for it to be warm before frying.
posted by mumimor at 1:42 PM on May 16, 2022 [3 favorites]

Some people will tell you it's high risk and never do it or you'll die. Others will tell you that's how there family has done it for 50 years (or more!) and never had a problem.
The truth is somewhere in the middle. I've done it before and I may do it again, but it won't be a common thing for me.

The conservative USDA guidelines would say no, for sure. The NHS says no too, on grounds of food poisoning with Bacillus cereus
posted by SaltySalticid at 1:44 PM on May 16, 2022 [9 favorites]

According to Food Network website:

If you’re serving the rice and place it in a bowl on your table (at room temperature), then it must be refrigerated within two hours of cooking. If the rice sits out for two hours at room temperature or one hour if the temperature is 90 degrees fahrenheit or above (like eating outdoors), then the rice should be tossed.

Some dried rice has a dormant bacteria that is activated by cooking and will grow then if kept at room or warmer temperatures.

Rice is cheap. Throw it out.
posted by tmdonahue at 1:44 PM on May 16, 2022 [7 favorites]

Bacteria is rapidly killed at temperatures of 150* and above. If, you are confident that your keep warm setting kept the rice at 150* or higher all night then you should be safe. If the rice spent time at room temperature or warm outdoor temperature (anything up to 149) then you should toss it.
posted by metahawk at 1:48 PM on May 16, 2022 [3 favorites]

I leave regular rice in the rice cooker overnight all the time, no problem. However, if I'm doing a recipe that incorporates chicken stock, bits of meat or sausage, for example, I wouldn't leave it out.
posted by gimonca at 1:53 PM on May 16, 2022 [3 favorites]

If there's rice left over from dinner, can I leave it in the cooker overnight and eat it ... without risking food poisoning?

We do it all the time, when I forget, without food poisoning. I always turn the cooker off right after it's done, however. Keeping it warming for hours doesn't seem like I'm doing the rice any favors.
posted by Rash at 1:55 PM on May 16, 2022 [1 favorite]

Related questions previously, previously, and previously. But the simple version is what tmdonahue said: Rice is cheap. Throw it out.
posted by Mr.Know-it-some at 1:55 PM on May 16, 2022 [7 favorites]

I'm sorry, I got confused by the first response on warm settings. If it's been held at 150 it is fine per FDA.. It will make the rice dry out and may be a fire hazard, but no food poisoning.
posted by SaltySalticid at 1:59 PM on May 16, 2022 [1 favorite]

If your rice cooker is, for instance, a Zojirushi with a keep warm setting, the answer is "as long as the keep warm setting will stay on," which is usually 12 or 24 hours (often there's a choice between normal/extended keep warm). It sounds like that's the case here, as 150 F is right around the temperature rice cookers with this setting aim for. That said, I don't think the rice is as good as freshly cooked after 8 hours at 150 F. So, if you're confident the rice was at 150 F or above the whole time, it's likely fine, if not as tasty as it could be.

Rice that isn't held above 140 F should be refrigerated as soon as possible and consumed as quickly as possible thereafter. The bacteria mentioned above is Bacillus cereus, and you do not want to mess with it. Durable Bacillus cereus spores are often present on rice and are *not* killed by cooking--In fact, steaming rice is the perfect prompt for them to wake up and begin reproducing and producing toxins, which can happen within 2 hours post-cooking if the rice is held at temperatures between 40 F and 140 F. Once this happens, reheating the rice again, even to above 150 F, does nothing to make it safe to consume, as the heat-stable toxins are enough to cause illness. You do not need to be infected by the bacteria to get sick (though that can happen too!).

You'll occasionally see reports of young and healthy people dying from Bacillus cereus toxin exposure, but it's more likely to just give you watery/bloody diarreha and vomiting. It doesn't matter if there's chicken broth, meat, or anything else in there. Rice alone is enough to grow a nice batch of Bacillus cereus. Seriously, don't mess around with rice.
posted by pullayup at 2:00 PM on May 16, 2022 [32 favorites]

If the rice is being maintained at 150F, then it is totally fine to eat if stored at that temperature overnight. There's no risk of botulism growth at 150F (or of anything else that you need to worry about). The USDA, for instance, says you can hold food at 140F or above indefinitely.

You probably are using about half a kWh of electricity leaving the rice cooker on warm overnight though, which isn't a huge amount, but also isn't nothing.
posted by ssg at 2:23 PM on May 16, 2022 [1 favorite]

Everybody does this, but:
Can reheating rice cause food poisoning?
Uncooked rice can contain spores of Bacillus cereus, bacteria that can cause food poisoning. The spores can survive when rice is cooked.

If rice is left standing at room temperature, the spores can grow into bacteria. These bacteria will multiply and may produce toxins (poisons) that cause vomiting or diarrhoea.

The longer cooked rice is left at room temperature, the more likely it is that the bacteria or toxins could make the rice unsafe to eat.

so I don't leave the rice out anymore. This is adulting is not popular.
posted by theora55 at 2:50 PM on May 16, 2022 [3 favorites]

Bacteria is rapidly killed at temperatures of 150* and above.

The problem is Bacillus cereus produces toxins that are what make you sick and are not destroyed by heat.
posted by Candleman at 3:16 PM on May 16, 2022 [4 favorites]

Anecdata incoming. I use my rice cooker all of the time. It's some model of Zojirushi. I'm not sure which. I cook 2-3 cups of rice at a time and when it's finished, I leave it in the cooker. My cooker keeps the rice hot. I then pull rice from it for the next several days — until it's gone, becomes crusty/gummy, or I simply want fresh rice. I have been doing this for years. I have never ever had a single problem with food poisoning from doing this.

I learned this method or rice cooking from a Korean co-worker. We used to travel together for work, and he'd bring his rice cooker. He'd fix a batch of rice on Monday nights, then eat from that same batch for the entire week. (His rice cooker too kept the food hot.) As far as I know, he never suffered from food poisoning either.

It has never occurred to me that doing this might be problematic. I just checked the manual for my Zojirushi, though, and it cautions against keeping rice for more than twelve hours. Whatever. I see no reason to change what has worked for the past 30 years...
posted by jdroth at 3:52 PM on May 16, 2022 [2 favorites]

pullayup et al, methods adjusted accordingly, 150°F, thanks for the enlightenment.
posted by Rash at 6:20 PM on May 16, 2022

Zojirushi with a keep warm setting, the answer is "as long as the keep warm setting will stay on," which is usually 12 or 24 hours

I have a Zojirushi and do this all the time. I don't think I've had food poisoning.
posted by corb at 6:36 PM on May 16, 2022

I have a Zojirushi and I do what jdroth does. Like, all the time. For years and years. I never don’t go two whole days and have gone three a few times too. Would I do this if the rice was at room temp, NO. But in my mind this is the principal benefit of a rice cooker. I mean it’s easy to cook good rice in a pot on the stove. The whole point of the cooker is to have rice at the ready for every meal.
posted by HotToddy at 6:46 PM on May 16, 2022 [2 favorites]

The main danger here would be if there was a power interruption during the night and the rice cooker automatically returns to a keep warm setting, and you ate that rice unaware of that fact. As mentioned above, reheating rice that has cooled to room temp will not make it safe to eat again, so you'd want to be sure the power remained on while you weren't there to watch it.
posted by Aleyn at 10:43 PM on May 16, 2022 [1 favorite]

The can I eat here is a question of probabilities. You will likely be fine 99 out of 100 times that you do this. One out of 100 times you will get terrible food poisoning and regret it. This 1 out of 100 happened to me (leaving guacamole out, not rice, but the same kind of thing) and it sucked so bad I will never take another chance. So my vote would be: no, there's bacteria in there!
posted by dis_integration at 9:31 AM on May 17, 2022

I eat rice that's been in the Keep Warm setting overnight and never had a problem. But the risk is real, and you shouldn't do this. Put it in the fridge.
posted by AlSweigart at 11:00 AM on May 18, 2022