How Do Rice Cookers Work?

many cuisines around the world. But before the invention and adoption of modern kitchen technology alike electric and gas heating elements, cooking rice was a finicky, hours long process that required you to stand around over a cast iron pot, making adjustments to a coal or wood fire in order to get the heat just right during different parts of the cooking process. Although simple electric rice cookers go back to the nineteen twenties in Japan, the first commercial one for

home use didn't debut until nineteen fifty six from Tashiba. People, and perhaps specifically women who often took on the task were Ready. Company records show that just four years later, about half of Japanese homes had a rice cooker. These days, rice cookers range from basic models that'll run you less than thirty bucks to ones with fancy features that cost over five hundred and Although they're ostensibly meant for cooking

you know, rice, they can be very versatile. Some people use rice cookers as their primary cooking tool for everything from spaghetti to spare ribs to scrambled eggs. So today let's talk about the technologies behind rice cookers. Rice needs two things to go from hard, shelf stable grains to tender morsels, lots of water and lots of heat. You generally accomplish this by boiling grains of dried rice in water anywhere from equal parts of each to twice as

much water by volume. The rice is done when all of the water has been absorbed and or steamed off, and the grains are whatever degree of tender you're looking for. It is ideal if you can do this without melting a layer of rice into a sticky, burnt mass at the bottom of the pot. There are a few ways to accomplish this automatically. Most start with an electric heating element set into a base which can also hold a cooking pot. You add rice and water and cover with

the lid that came with the appliance. The heating element heats the pot, which boils the water. But how does it know when it's done. The classic technology, the least expensive. The type I've got operates on a simple heat sensitive magnetized switch. Okay, you turn on this type of rice cooker by pressing down a switch on the outside of the unit, and when you do, you'll hear a little clock.

That's because the switch is connected to a lever that brings two surfaces in contact with each other that are electrically conducive. This completes an electrical circuit and powers the heating element. The circuit stays closed because the two surfaces are magnetic, but one surface, the upper surface of the pair, is made of a material that's only magnetic up to about one hundred and two degrees celsius, which is right above the boiling point of water. This is a very

clever bit of physics. Water boils at one hundred degrees celsius and won't get hotter than that at normal Earth pressure. So as long as there's water in the pot as the rice is cooking, the temperature at the bottom of

the pot will hold steady. At one hundred the temperature is in check thanks to the presence of water, but when it's all absorbed and or boiled off, the heating element can get to work on the pot and or the rice itself, which can get considerably hotter than one hundred degrees at normal Earth pressure, so the temperature at the bottom of the pan leaps up, at which point our temperature sensitive magnet stops being magnetic and drops the other half of the pair, breaking the circuit and turning

the heating element off with another little clunk. Except in a lot of rice cookers like this, the heating element doesn't turn all the way off, but rather switches to a warming function. This works thanks to another type of heat sensitive switch called a bimetal switch. A bimetal switch is a type of switch that's made up of two types of metals sandwiched together. Makes sense, right. Each of the two is chosen because they are bendable and because

they expand at different rates when exposed to heat. So the switch starts out flat but will bend one way or the other at different temperatures because the metals are expanding or shrinking at different rates, and you can use this property to connect and disconnect a circuit at different temperatures. In the case of our rice cooker, at around sixty

degrees ce elius, that's one forty fahrenheit fairly cool. The switch bends and connects the circuit, turning the heating element on a butt at around eighty celsius or one hundred and seventy five fahrenheit fairly hot. The switch bends the other way, breaking the circuit and turning the element off. It will keep toggling, holding the temperature of the pot nice and warm until you unplug the unit. But of course we humans are not confined to manual physical switches anymore.

Digital rice cookers contain digital thermometers connected to a simple computer that can be programmed at the touch of a few buttons on the outside of the unit to heat or warm the pot, two particular temperature settings, four particular lengths of time, like the way that we use standard microwaves. Computer controlled rice cookers were first introduced in nineteen seventy nine. But if you are going to go ahead and put a computer into a rice cooker, why not ask it

to do a bit more work for you. Rice cookers were one of the first home appliances to make use of the theory of fuzzy logic, which was developed by computer scientists in the nineteen seventies and now helps everything from washing machines to refrigerators to subway cars function. Fuzzy logic is sort of what it sounds like, logic with variables. Digital devices operate on boolean logic, which means ones in zeros you know on or off, yes or no. Fuzzy logic opens up the field of answers to all of

the numbers in between one and zero. Devices programmed with it can recognize an almost yes versus a slightly yes and act accordingly. This lets you program algorithms that take variables into consideration, like not just is the pot hot, but is it getting hotter quickly, and then make a decision about how to control the temperature based on that. Idea is that these machines can adjust for the actual

circumstances occurring in real time. Maybe the ambient pressure is making the cooking go faster, or you added too much water, and it can cook the rice perfectly regardless. It's way better than just using on off temperature settings, and probably better than any adjustments a hungry and impatient human might make.

While fuzzy logic rice cookers function under the same premise as basic models, their mathematical programming can deliver a slew of customized cooking options, making precise fluctuations in cooking time and temperature depending on the programs selected. These may include settings for white rice of varying textures, sushi rice, jasmine rice, brown rice, germinated brown rice, mixed rices, knge steel cutoats, rapid cooking, extended warming, and reheating. And that's just the beginning.

Some machines have settings for steaming foods, baking cakes, auto cleaning, and delayed timers, so you can preset the machine to start cooking at a particular time. Oh and if you do want a layer of crisp, golden brown rice at the bottom of your pot for dishes like tadig, there are rice cookers for that too. You add a bit of vegetable oil to the pot, and after the main cooking is done, a timer holds the pot to the

heat long enough to crispit. There are also rice cookers out there that don't use a standard electric heating element. These days, you can find models that use induction heating technology, which I could have sworn had already done an episode about, but I have not, and I'll have to rectify that in the future. Very basically, induction cookers don't waste energy heating an element that then heats a pan, but rather

use magnetic fields to heat the pan directly. There are also pressure rice cookers, which seal and pressurize their contents to allow for faster cooking times and hotter temperatures. Pressure cooking also a whole different episode. Whatever kind of rice cooker you're using, there are all kinds of recipes out there for how to get the most out of it. When it comes to rice and beyond, at a certain point,

it's a hot pad with a fitted pot. Anything you want to warm or cook, especially anything involving a lot of liquid, can be done in a rice cooker with enough tenacity a rice cooker. Poached fruit, hard boiled eggs, homemade soups, whatever you're cooking in it. Take a moment to appreciate your humble or not so humble rice cooker, and if you don't have one, consider picking up a basic model. After all, it's a robot that, if it could want things, would want you to eat good rice.

That's a good robot to have around. Today's episode is based on the article how rice cookers work on HowStuffWorks dot com, written by Jessica Tooothman for more about the history of rice cookers. Check out my other podcast Savor for the Warm and Fuzzy rice Cooker episode. Brainstuff is production by Heart Radio in partnership with how stuffworks dot com and is produced by Tyler Klang. But four more

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