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How Does a Rice Cooker Work?

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How Does a Rice Cooker Work?

A rice cooker is definitely for anyone and everyone, no matter where you live. From standard devices to high-tech computerized models, there’s no shortage of rice cookers that can suit each individual or household’s needs. 

But because they have been around for so long, we tend to forget what an incredible piece of technology they are. Even the simplest rice cooker employs a unique way of cooking. In this guide, we’ll go through the science behind this beloved kitchen appliance and find out exactly how a rice cooker works.

What is a Rice Cooker?

A rice cooker is an automated electric appliance built for cooking rice. There are different types that range from standard, to digital, to more multifunctional ones. Each one has its own unique set of functions and features, but overall, the appliance is built to make creating a warm batch of rice a lot easier by automating the process using unique technology.

Who Invented the Rice Cooker?

Cooking rice used to be a tough feat. Before automated cookers were invented, people had to manually cook rice on a stovetop. Without the automation of today’s rice cooker, it was a lot harder to get the perfect, fluffy rice that we now get to easily enjoy.

Thankfully, manufacturers found a way to simplify the process. Japanese brand Toshiba created the first automated rice cooker back in 1955. While the technology back then was a lot more primitive, this appliance became the blueprint for the standard rice cookers we know today.

How Rice Cookers Work

The cooking cycle in a conventional rice cooker can be divided into four stages: sitting in water, boiling, absorbing water/steaming, and resting/warming.

Sitting Stage

Once you’ve loaded the rice and water into your pot, its weight will press down on the thermal sensing element located at the bottom of the device’s main body. Plug in the rice cooker and turn the power on and the heating plate will conduct heat to your pan.

Heating and Boiling

The goal is to get water to boil, and the amount of time it takes to get there will vary on the material of the inner bowl as well as the amount of water. One cup of white rice will take around 15 minutes to cook.

Absorbing Water/Steaming

You’ll notice your rice cooker will start letting out steam upon boiling. At this point, all the remaining water will also be absorbed by the grains. When the boiling water is all gone, the inner pot’s temperature will once again start to rise.

This is where the mechanism of a rice cooker gets a little complicated! In standard ones, there is a small button within the heating component that is loaded by a spring. At the bottom of this spring is a small but powerful permanent magnet. The button is made of material that is attracted to magnets. Press it down and it comes into contact with the magnet and stays there by magnetic force. When you press the outer switch down to cook mode, the device will go into full power.

However, the button loses its magnetic attraction once it reaches a certain heat temperature. Usually, this temperature point is just a little higher than boiling. This lets it act as a “temperature-dependent kill switch,” because once the inner bowl surpasses the boiling point, the button (which mirrors the temperature of the pot) becomes too hot to be attracted to the magnet at the bottom. The loss of magnetism will depower the lever that allows the cooker to bypass its electric resistor. The result is the device going from full power mode to warm mode. The movement of the lever can be seen when the outside switch jumps up from “cook” to “warm”.

In short, the standard rice cooker is completely dependent upon magnets that can sense temperature, and the heat of the water.

Resting Stage

This is also known as the keep warm stage. A standard rice cooker will have the power cord pass through a resistor to limit the current and thereby keep the inner pot at a low, warming temperature. Many models have the ability to keep rice warm for hours on end, and some stay warm as long as they’re plugged in.

Video Summary of How Rice Cookers Work

How Hot Do Rice Cookers Get?

The water will reach boiling temperature at 100 degrees Celsius or 212 degrees Fahrenheit, at which point it will stop getting hotter and stabilize. The water will then turn into steam or get absorbed by the grains, triggering the rice cooker to switch to warm mode.

How Does the Warming State of a Rice Cooker Work?

When not in cook mode, the electric current that runs through the power cord and into the device is limited to a low power so the rice stays warmed, but not cooked. This is done with an electric resistor that is triggered once the temperature of the inner pot goes past 100 degrees Celsius.

Does a Rice Cooker Cook Rice Faster?

There isn’t a noticeable difference between the cook times of a standard rice cooker and that of a regular stovetop pot. However, this can also depend on the material used. Some metals can conduct heat faster, which might result in faster cooked rice.

Are Rice Cookers Safe?

You can use a rice cooker for cooking a perfect batch of rice. And yes, they’re completely safe! Each part of the rice cooker is made of non-toxic material that will not only cook rice, but also ensure nutrients are stored in your food.

Parts of a Rice Cooker and Their Functions

Understanding its key components will help you use a rice cooker easily. While there are different types of rice cookers out there, most of them have six main parts:

    1. Main Body. This is the exterior pot that houses the inner cooking pan, heating plate, as well as the main circuitry found under the base. It’s usually made of stainless steel or plastic.
    2. Inner Pot. The inner cooking pot is where all the cooking happens. Once it’s turned on, the plate will start to heat and boil the water in the pot. This is usually made of non-stick material, either stainless steel or ceramic.
    3. Heating Plate. Depending on the variety of cooker, the heating element will either direct heat to the bottom of the pan or heat the entire pot (IH).
    4. Thermal Sensor. This is the mechanism that detects whether the temperature has reached boiling temperature and signals the device to stop cooking.
    5. Indicator lights. Found in standard rice cookers, these lights let you know if the device is in cook mode or resting in warm mode.
    6. Navigation buttons. For more advanced devices, you’ll find a display menu for selecting different settings such as delay timer. In multi-cookers, this is where you can select various cooking programs.

Types of Rice Cookers

Standard/Conventional

The standard rice cooker is one of the oldest types of rice cookers in the market. Basic and cheap, these devices are deceivingly simple pieces of technology that are still able to make perfectly cooked rice every time. All you need is the right amounts of rice and water, and you’re good to go! 

Although they aren’t as fancy as newer kinds, there’s a reason they have stood the test of time. For those who just want to make rice and nothing more, this type of rice cooker is your best bet.

Digital Rice Cooker

The digital rice cooker is an improved version of the conventional type. They also include smart features that are navigable through a digital control panel, giving users more control over how their rice is cooked. Some of the added features of such models include an on/off setting, food warming, delay timer, and cooking timer. Many also have specific programs for cooking different rice varieties, such as brown rice or white rice.

Multi-Functional Rice Cooker

A multi-functional rice cooker can cook not only rice, but different recipes as well. It can pressure cook different meats, steam vegetables, boil soup, and even create a whole cake. This is thanks to the digital programming built into it, letting the user select different cook modes through a navigable digital control panel. 

Usually, a multi-functional rice cooker will also have different cook settings such as steam, soup/broth, slow cook, pressure cook, and more. 

Plenty of these multi cookers are able to create a slew of recipes because of fuzzy logic or microcomputer technology. Fuzzy logic technology gives these devices an additional sensing capability, in that they can easily detect when minute changes in temperature and cooking time are needed. The algorithm is programmed to take note of this information then respond accordingly.

Induction Heating Rice Cooker

While multicookers may seem like the most advanced devices out there, induction heaters or IH cookers actually take the cake. In cooking rice, it’s a great way to heat the pan more evenly and yield a perfect batch.

An induction heating cooker will use friction from a magnetic field to generate heat throughout the entire inner cooking pot. Yes, it can heat the entire pot, unlike most rice cookers which only conduct heat from the bottom of the pan and up. The even heat distribution ensures each grain of rice is cooked perfectly.

Pressure Cooker

These are the kind to cook rice more quickly, because as the name suggests, they use both heat and air pressure that is sealed within the inner bowl in order to cook the rice. With their ability to speed up the cooking cycle, a pressure cooker is perfect for individuals who are always on the go.

Uses of Rice Cookers

Whether you eat rice three times a day, every meal, or simply have it as the occasional side dish, a rice cooker is a handy appliance to have. For starters, you can use a rice cooker to create different varieties of rice, including:

  • Long grain white rice
  • Brown rice
  • Sushi rice
  • GABA rice

Some standard rice cookers come with a detachable steam tray for fish, vegetables, and any other food you wish to reheat. Multi cookers have the advantage of being able to cook not only rice, but also fish, meats, vegetables, eggs, and even cake. That’s why many also come with an app or cookbook for different recipes, because you’ll want to try every dish on it!

How Long Do Rice Cookers Take?

This all depends on the heat, inner pot, how much water the grain type calls for, etc. 1 cup of white rice will usually take 15-17 minutes on a dedicated appliance. A cup of short grain white rice should have 1 ¼ cups of water, while short grain brown rice has a water-to-rice ratio of 2:1. 10 cups of water will naturally take longer to boil than, say, 2 cups of water.

What Can You Make in a Rice Cooker?

What many don’t know is that a dedicated rice cooker can also do more than just cook rice! Some food that can be cooked in a rice cooker include:

  • Fluffy pancakes
  • Quinoa
  • Oatmeal
  • Soup
  • Barley
  • Dumplings
  • Rice pudding

Of course, all of these require different steps and instructions to cook perfectly if you’re using a dedicated rice cooker. However, it goes to show that even the simplest device can still be a versatile appliance.

How to Cook Rice In a Rice Cooker?

Whether you want to make jasmine rice, white rice, brown rice, or mixed, you have to remember that different types of rice follow the same general instructions. Here are the basic instructions for making rice:

  1. Using a measuring cup, put your grains in a rice washer/pot. Rinse the rice grains with running water in a rice washer or the inner pot of your rice cooker. Add water until the grains are completely submerged. 
  2. Take two handfuls of grains and rub them against each other. This ensures the dirt, as well as excess starch, is stripped away.
  3. Your water will have turned cloudy by this point. This is due to the dirt and other debris found in your uncooked rice. Rinse out the dirty water, then repeatedly rinse the rice as shown in steps 1-2 until your water is no longer cloudy or muddy. This takes about 10 minutes. Once your water is clean, your grains are safe to cook.
  4. Using a measuring cup, add water into the pan along with your grains. How much water you need will depend on how many cups of rice you plan to cook as well as the type of rice. 
  5. Once the rice and water is in the bowl, select the cook setting or push the cook switch on your device. Now all you have to do is wait!
  6. Once the cooking cycle is over, the device will switch to Warm mode. Let it warm for 10 minutes, then fluff the rice and serve using a rice paddle. Now you can enjoy a batch of freshly-cooked, fluffy rice on your table!

Rice Cooker & Rice Water Ratio

Water to rice ratio is probably the biggest factor that determines how well your rice is going to turn out. The tricky part is how much water you have to add to make rice, and it all depends on the quantities as well as the variety. Here’s a quick water-to-rice ratio guide for each type of rice:

White Rice. For this common grain, the rice to water ratio is simple. Short grain, medium grain, and long grain white rice don’t need a large amount of water for cooking. For 1 cup of rice from this variety, you will need:

  • Long grain rice (Basmati rice/Jasmine) – 1 ¾  to 2 cups water
  • Medium grain – 1 ½ cups water
  • Short grain (Sushi rice or Japanese rice) – 1 ¼ cups water

Brown Rice. Brown rice is a whole grain, full-fiber variety, hence requires a longer cooking time. If you want to prepare brown rice, you’ll have to wait around 40-50 minutes on a standard cooker. It also needs more water. For 1 cup of rice from this variety, you’ll need to add:

  • Long grain rice – 1 ¾ cups water 
  • Short grain – 2 cups water

What Temperature Should Rice Be Cooked At?

Rice cooks at boiling temperature (100° celsius or 212 F). Usually, automated rice cookers will sense when the water starts boiling and stop the cooking process. However, if you’re creating rice manually, you can use a cooking thermometer to monitor your pan’s temperature.

How to Clean a Rice Cooker

Maintaining a rice cooker ensures it lasts as long as possible. Cleaning a rice cooker will depend on what type you have. 

For a standard rice cooker as well as electric pressure cooker, simply wipe the outer lid and inner cooking pot with a damp cloth. If dirty, use a sponge and soap to thoroughly clean away any stains on the inner pot. Use a damp cloth to clean the inside of the main body, but make sure not to wet the heating plate.

If you have an induction heating rice cooker, you can wipe both the sides as well as the surface of the interior with a damp cloth. The lid usually comes with a detachable stainless steel cover that can also be wiped down.

Some newer models will have a detachable steam cap that you can easily remove and wipe down, as well as a dew dish located at the back that collects moisture. To clean, remove the water and wipe with a damp cloth. Most accessories, such as a rice paddle and measuring cup, are dishwasher-safe.

How Much is a Rice Cooker?

These appliances can range from as little as $20 to $500. Usually, the pricier ones are those with all the fancy cooking technology, like fuzzy logic or induction heating. They could also be the larger capacity ones. If you have no need for those extra features, stick to a budget-friendly dedicated rice cooker.

Are Rice Cookers Worth It?

From pressure cookers to instant pots, it is almost guaranteed that you will find one that will change your kitchen routine forever. As long as you invest in an appliance that suits your needs (especially if that need is making the best rice possible), we say they are definitely worth it.

Advantages of a Rice Cooker

It automatically cooks the rice

Gone are the days of manual stovetop rice cooking. With the advent of automated rice cookers, you’re guaranteed a perfectly cooked batch of rice every time. As long as you get the rice to water ratio right, of course.

It’s easy to clean

Many of these appliances can be cleaned with a good old damp cloth, or a soft sponge with dishwashing soap. Just make sure to clean them regularly, as well as read the instructions to know the best way to maintain your device.

It keeps rice warm

There’s nothing sadder than eating a cold plate of rice because you were too busy to get to the dinner table right away! Luckily, most models have a keep-warm function to store your rice while you’re busy running errands.

What Kind of Rice Cooker Should I Buy?

There’s no such thing as a one-size-fits-all rice cooker. True enough, the best one will always depend on your individual needs and preferences. Some factors you will have to look at are:

  • Large vs. Small
  • Simple vs. Advanced Technology
  • Electric vs. Induction Heating
  • Dedicated vs. Multifunctional

Are you a stay-at-home mom of five? Get a rice cooker that can make at least 6 cups of cooked rice. If you’re a single dweller, you may opt for a small rice cooker instead. Those who can’t afford to get a whole arsenal of kitchen appliances would fare well with a multifunctional appliance to create a whole meal.

Troubleshoot Rice Cooker Problems and Solutions

When you have an electronic appliance, coming across different problems and issues is par for the course. But you might want to hold off on trading your device for a new product. Instead, here are a few ways you can fix your device without resorting to buying a new one.

Rice Cooker Won’t Turn On

If you’ve checked the power cord for any frays, the problem might have to do with the thermal cutoff. The thermal cutoff can break if the rice cooker goes beyond a certain temperature threshold. If you tend to overheat your cooker, then this is the likely culprit. To fix, unscrew the bottom of the pan and replace the thermal cutoff.

Rice Cooker Cook Button Not Working

If the switch won’t stay in cook mode, then the likely problem might be a faulty thermal sensor. The button found in the middle of your heating plate is most likely the culprit, because it no longer attracts the magnet found under it.

Rice Cooker Light Not Turning On

If your device can power up but doesn’t indicate whether you’re in cook mode or warm mode, the likely diagnosis is a faulty LED.

How to Repair Rice Cooker

  1. Unplug the device from the power source and remove the lid and inner pot as well as any accessories.
  2. Remove the screws at the bottom of the base and open it.
  3. Remove the heating component to test it with a multimeter. If your heating component is fine, the next step is to test the resistor.
  4. Sometimes, the switch contacts become dirty or corroded, resulting in a break in the flow of the electrical current. If they are burned, they might need to be replaced. You can also test the switch to see if the contacts touch when you push it. If they don’t, simply use the screwdriver to move the contacts closer.

If all else fails, most of these appliances will come with a warranty and some only require a quick sign-up using your email address to avail of it.

Final Note

Using a rice cooker is intuitive and easy. The technology behind even the simplest models ensures fuss-free, perfect rice on each try. So really, there is no reason why you shouldn’t have this handy kitchen assistant on your countertop. If you’re interested in knowing all about different brands, check out our guide to the best rice cookers.

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Ji-hyun

Hailing from California, USA. Ji-hyun is a Korean American 🇰🇷🇺🇸 with two growing boys who eat their weight in rice each week. After graduating UCLA & becoming a mom she started We Know Rice as a guide for all the students and moms out there looking to cook healthy and filling meals.

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