Whether you’re a rice cooker enthusiast or have just bought your first one, you’re probably eager to learn how to use it best. In particular, people who have a better-than-basic rice cooker notice that there’s a “keep warm” function along with basic cooking features.
The “keep warm” feature is typically activated after the normal cooking cycle is over, and you can keep it going for several days, but is it safe to do so?
You can safely leave your rice cooker on warm when used for a short period of time. The “keep warm” feature keeps the rice at a safe temperature for several hours, so you can walk away for a while without burning it. However, if you leave it too long, it can lead to overcooked rice and other issues.
This article will look at how to use your “keep warm” feature properly. I’ll also consider how improper use can cause problems, ranging from dried-out rice to a fire, so you’ll know how to get the best results out of your rice cooker safely.
A Rice Cooker Works Like a Hot Pot or Electric Kettle
At their most basic, rice cookers prepare rice by adding heat to the water and rice in their cooking vessel.
Regardless of the kind of cooker you have, all of them direct you to add one part rice and two parts water to the cooking pot. Once you put your rice and water inside, place the pot into the cooker, and then turn the cooker on.
But what happens when you turn the pot on?
As with other countertop cooking pot devices, electricity creates heat, which then transfers to a heating element. With rice cookers, this element is situated underneath the cooking vessel.
During cooking, heat is applied to the pot and its contents through conduction, which is the same process that a spoon inserted into your hot soup makes.
Stovetops also work through conduction, though stoves operate differently.
Rice Cookers Know When To Stop the Cooking Process
If you understand how rice cookers know when to stop the cooking process, it’ll be easier to know how leaving a rice cooker on warm can be safe.
In a nutshell, rice cookers have sensors that tell them when the rice has finished cooking. When water boils, the rice will absorb the water and become soft. Then, the temperature will rise once only steam is left.
At this point, temperature sensors tell the heating elements to adjust the temperature.
The Auto-Off Feature Is Similar to Countertop Appliances
One of the essential safety features of a rice cooker is that it immediately stops the cooking process when the appropriate temperature is reached.
This feature is similar to hot pots, electric tea kettles, and toasters, and for each of these items, the intention is to ensure that you get the correct cooking results.
The problem comes when the continuous operation of any of these devices is at full power, there’s a risk of fire.
Toast can catch fire if overdone, a kettle boiling over can melt, and hot pots also burn food. Luckily, by switching off automatically, these problems are minimized. Unless there’s a faulty switch, you can typically expect the device to operate safely.
When the Rice Is Done, It May Enter “Keep Warm” Mode
Unlike electric kettles and toasters, both of which always switch off completely, rice cookers sometimes have a keep warm mode.
In fact, this function is increasingly common even with lower-end cookers. And there’s a good reason for this: keeping rice warm automatically is very convenient when you want to eat the rice a little while after cooking.
Another great thing about the warm mode is that rice needs a few minutes to rest before eating.
If you’re making rice on the stove, turning the heat off and keeping the pot covered will help it stay warm while the rice sets. However, a rice cooker’s warming feature keeps the rice warmer longer, because heat is still applied to the heating element.
Because of this, you can have hot rice much longer-sometimes for days.
The Keep Warm Mode Is Designed To Maintain Food Safety
As mentioned above, the heat level used during “keep warm” cycles is much lower than the cooking temperature. In particular, cooking rice requires boiling water.
Water boils at a temperature of 212°F or 100°C. On the other hand, keeping the rice warm only requires a temperature of 140°F or 60°C.
Why is this temperature difference significant?
While you can’t cook efficiently at lower temperatures, the warm setting uses the minimum temperature required for food safety. In fact, according to the USFDA, hot foods must be kept at 140°F (60°C) or higher unless consumed within two hours.
This principle has a simple application for rice cookers. As long as you don’t open the cooker and take food out too often, the keep warm feature will prevent food poisoning.
On the other hand, frequent opening of the cooker will cause the temperature to drop and not come back up in a reasonable time.
Rice Cookers Are Designed To Run in Warm Mode
Another thing to consider is that rice cooker manufacturers intend for the appliance to stay in “keep warm” mode for several hours, if necessary.
This feature comes in handy when you get a phone call just before dinner or if the rest of your meal takes longer than expected to cook.
Then, just like an oven, you can walk away from the rice cooker for a while and not worry about it. In addition, the warming feature keeps temperatures low enough to prevent burning.
You Still Need To Be Careful About Fire Risks
With that said, there’s always the risk of an electrical fire if you aren’t careful.
Electrical safety experts recommend that you keep the cooker away from flammable objects any time it’s operating. By doing this, you’ll keep the steam from setting something on fire. Plus, in the unlikely event that your cooker sets off sparks or has an electrical short, there won’t be as much fuel nearby to feed a fire.
Despite the safety features, it’s usually unwise to leave a rice cooker alone for too long because monitoring your cooker while operating is the best way to ensure that you’ll shut the cooker off if there’s a malfunction.
One reason for this precaution is that the keep warm feature on rice cookers was designed to run indefinitely. By contrast, a slow cooker is typically intended to run for many hours but has an automatic timer that eventually switches it off.
Warming Features Don’t Work With Everything
The reason you need to understand how rice cookers work is that it will help you understand a critical safety vulnerability.
When cooking rice or any other product that cooks thoroughly when all water is absorbed, the steam causes the cooker to switch to warm mode. However, as cooker maker Aroma Housewares points out, this principle doesn’t work if you’re cooking something that won’t absorb all the water.
Practically speaking, the inability of a rice cooker to switch to warm unless all water is absorbed means that you must switch the unit off manually if using it this way. Steaming vegetables is an everyday second use for a rice cooker, as is heating soup.
If you don’t turn the cooker off when done, it’ll run until all water is boiled off and create a fire hazard.
Leaving Your Cooker on Warm for Too Long Can Ruin the Rice
By now, we’ve established that it’s generally safe to leave a rice cooker on warm, as long as the food cooked is something that absorbs all of the water.
However, that doesn’t mean that it’s a good idea to do this for a long time. Not only are there dangers to leaving any appliance alone for long hours, but the rice will eventually lose its optimal taste and texture.
The Rice Gets Dry if Left on Warm Too Long
Even though a rice cooker’s keep warm feature stops the rice from burning for hours or days, the rice will eventually dry out. That’s because even though rice cookers keep the food covered, there’s still some evaporation of the water that is absorbed into the rice.
You can see how this works with hot food on a plate. Even though the food isn’t cooking anymore, the food is still hot enough to release steam for some time.
Rice Can Develop Off Taste or Color
Similar to the evaporation of water, the taste of rice changes a while after cooking. While the rice remains safe to eat for a few days, it might not be appetizing anymore. Rice cooker users report rice turning yellow or getting tough if left too long.
While outright burnt rice is unlikely due to safety features, extended exposure to heat from a cooker can still ruin your rice. Maybe this is one reason why leftover rice is typically refrigerated in places like Singapore.
You Can Leave the Rice Cooker on Warm for Several Hours
Despite the risks of leaving your rice cooker on warm for excessive amounts of time, there’s still a generous time window for safe use. All experts agree that keeping the rice on the warm cycle between four and twelve hours produces satisfactory results. Not only can the circuits handle this length of time, but the rice is unlikely to become inedible in this time window.
There are a few factors that determine how long your rice stays tasty in the cooker. For one thing, a larger-capacity cooker has an advantage, because larger volumes of rice tend to lose water more slowly.
The other major factor is cooker features, as some high-end models are designed to keep the rice moist for longer. In this case, your mileage may vary.
Experience will help you learn your cooker’s limits over time.