What is a Rice Cooker?
A rice cooker is a kitchen appliance designed to sit on the countertop and cook rice with no supervision. It is made of a heating element with thermostat control under a non-stick inner bowl. These appliances are useful for restaurants and home use alike.
Toshiba introduced the first one onto the market over 60 years ago, and other companies soon followed suit. Today, they have various features, such as the Keep Warm function, which we shall consider today.
Keep Warm Function
Like a slow cooker or an electric pressure cooker, rice cookers also come with the keep-warm function. Rice cookers’ Keep Warm function does exactly what it says – keeps your rice warm once it is cooked for later consumption.
However, what happens when you use this function for an extended time? Is your rice cooker keeping temperatures around the safety level? A rice cooker’s Keep Warm function allows you to skip the reheating process, but at what cost?
Rice Cooker Keep Warm Temperature Function
A good quality rice cooker will keep temperatures at around 140 degrees Fahrenheit, but it is safest to check it with a food thermometer since there is no temperature indicator. 140 degrees Fahrenheit and above is the temperature range where your food is safe from bacterial infestation.
However, according to scientific studies, a bacteria known as Bacillus Cereus can sometimes survive the boiling process and create a heat resistant bacterium within your rice when it’s kept at temperatures around 140 degrees Fahrenheit for periods longer than 24 hours, and sometimes even just 12 to 15 hours.
A bowl of rice infested with the Bacillus Cereus bacteria doesn’t smell bad but, upon consumption, can cause a mild stomach ache to a more serious case of full-blown diarrhea.
This is why you have to make sure your rice cooker – on Keep Warm mode – keeps the rice temperature above 140 degrees Fahrenheit. It is best not to hold the rice at the Keep Warm temperature for more than 5 hours. Some reasons are detailed below.
Dry crunchy rice
Over time, the heat will evaporate every bit of moisture from your rice and will leave you with a pot of unappetizingly dry rice. Even a temperature of around 140 degrees Fahrenheit can do this. Unfortunately, this temperature is high enough that people use the rice cooker – on warm modes – like a slow cooker.
A rice cookers’ warm mode can (very slowly) cook soup, sponge cake, stew, and a lot more. So, having something as delicate as grains of cooked rice sit in this hot atmosphere for too many hours will most certainly lead to undesirable results.
Power use and malfunction
Your rice cooker is an electrical appliance, meaning it will require electricity to keep the warm mode turned on. While rice cookers are economical to use under normal circumstances, more extended usage periods will drain substantial amounts of electricity.
Using the warm mode continuously for 2 days (please don’t do this!) can also lead to overheating and may end up burning the thermal fuse. For these reasons, rice cooker manufacturers always advise their customers to use the Keep Warm mode for no longer than 12 hours.
Some high-end rice cookers come with dual warm mode functionality. They have a Low Warm mode and a High Warm mode. The High Warm mode can take temperatures up to 176 degrees Fahrenheit. This is a safer temperature to hold your rice at to prevent bacterial growth.
So, rather than keeping rice warm for too long, we advise you to pack the cooked rice into a plastic container for refrigeration and later use. Not only will this help to retain the moisture, but refrigerated rice is also the best rice for cooking fried rice. It will also keep your rice edible for a longer period.
To conclude, although the warm mode is extremely convenient when used for an hour or two after cooking the rice, it is in your best interests not to use it for longer than that.