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How Do Pressure Cookers and Instant Pots Work?

How Do Pressure Cookers and Instant Pots Work?

Pressure cookers and instant pots are great tools for the kitchen. Both types of cookers have gotten a lot of attention in the past few years. These cookers can shorten cooking time and leave you with juicy, flavorful food. Many people prefer food cooked in a pressure cooker or instant pot over food cooked in a more traditional manner. But most people may not know how they work.

Pressure Cooker Vs. Instant Pot

While you probably have some idea what both instant pots and pressure cookers look like, you may not be aware of how they work. 

Pressure Cookers

One of the first things you need to know is that there are two types of pressure cookers: electric and stovetop. While these both cook in the same basic way, the way they function differs somewhat.

The biggest difference between the electric and stovetop versions of the pressure cooker is the amount of automation in the electric pot. Most electric pressure cookers will regulate the temperature and have a built-in timer that you can set. This allows you to turn the electric pressure cooker on, set your cook time, then walk away. 

A stovetop pressure cooker requires much more attention from the cook. Not only do you have to monitor and adjust the heat while the pot builds pressure, you also have to learn the proper heat settings to maintain the temperature without overpressuring during cooking. You also must use a separate timer, then turn off the stove when your food finishes cooking. However, one advantage of stovetop cookers is that it is sometimes possible to set them to a higher pressure than their electric counterparts.

Instant Pots

An instant pot is actually a type of pressure cooker. They have a pressure cooker setting, which is often the main function you see marketed. While it can sometimes cook at a slightly lower pressure than most pressure cookers, an instant pot still pressurizes the food to nearly the same pressure you see with an electric pressure cooker. This functionality works much like any electric pressure cooker.

But instant pots also have several additional features. Depending on the model you buy, you may see many additional buttons with presets for rice, slow cook, steam, saute, and yogurt, among others. This lets your instant pot take the place of multiple kitchen appliances. No longer will you need a separate slow cooker and rice cooker, your instant pot can take over for both.

The line between an instant pot and an electric pressure cooker is becoming increasingly blurred. More often, the electric pressure cookers are getting the added settings and features that used to be common only on instant pots. If you look at their marketing, some companies use the terms instant pot and electric pressure cooker almost interchangeably. 

How Pressure Cookers and Instant Pots Work

The basics of all pressure cookers and instant pots are the same. While there are variations to the features and functions of different models, they all have similarities.

Parts on all Pressure Cookers That Are The Same

All pressure cookers, electric or stovetop, contain these main parts:

  • The pot
  • A locking lid with a seal
  • A pressure regulator and steam vent
  • Safety valve or valves

The pot is the main part where the food goes. On a stovetop pressure cooker, this looks similar to any standard pot. In fact, one advantage of stovetop pressure cookers is that the pot can be used as a typical cooking pot without the lid, just like any standard pot you may have in your cabinet.

The lid on a pressure cooker locks on. Often, you accomplish this by rotating the lid into a slot. The lid also has a gasket to hold in the pressure. This can be some kind of rubber or silicone. 

Pressure cookers must have a pressure regulator. This valve will pop open and release the pressure if it exceeds the preset. Some models let you adjust this pressure, but some do not. Typically,  this comes in combination with a steam vent, which lets excess steam escape from inside the pot. 

Safety valves are an important part of the system. If the pressure inside the cooker rises to unsafe levels, the safety valve will open and let out the pressure. Under normal circumstances, the pressure regulator and steam vent maintain a safe pressure level, but these valves are a fallback to prevent damage or injury.

If your pressure cooker is a stovetop model, that’s pretty much all you get. There may be slight variations in how the lids lock, and the pan itself may have a slightly different design from one model to the next, but the basic stovetop model is pretty simple.

How Electric Pressure Cookers Are Different from Stovetop

While the basics are the same, there are some pretty significant differences in how instant pots and electric pressure cookers are constructed when compared to the stovetop models. Some of the additional features both kinds of electric cookers have are:

  • The pot sits inside an outer container and can be removed for cleaning
  • Built-in heating element, so a stovetop burner isn’t necessary
  • Onboard timer
  • Scheduling timer
  • Added safety sensors to prevent lid opening at dangerous times
  • Added cooking features, especially for instant pots

The removable pot makes cleaning easy, but it is also necessary since you shouldn’t submerge the main cooking unit. This is different from the stovetop pressure cookers, which have no electrical components at all.

Having a built-in heating element in an electric pressure cooker or an instant pot can be very handy when making a lot of food since they do not occupy a burner on your stove. This frees up the burner it would have used. It has the added benefit of an onboard controller that can take care of setting the cooking temperature to the proper level, so you won’t have to adjust it as it warms up or turns it off when the food finishes, which you must do on the stovetop.

The onboard timer and scheduler let you set a cook time, put your food in, and walk away. No more rushing back in to turn off the burner under the pressure cooker, it will do it for you. You can also set a time for the cooker to start, letting you fill it and leave it ready to go when you go to work. At the right time, your food will begin cooking so your meal finishes right when you are ready to eat. 

Many electric pressure cookers and instant pots include added sensors that prevent you from taking the lid off if the steam pressure inside is too high. This prevents injury and damage. 

Some electric pressure cookers and all of the instant pots have cooking features you won’t find on a standard pressure cooker for the stovetop. There are settings for rice, soups, different types of meat, and other specific foods. Even with all these great features, they still have the downside of taking up counter space, which could be a problem in a small kitchen.

How Do Pressure Cookers Cook Food?

If you cook moisture-laden foods, the heat that the food can reach inside is typically limited to the boiling point of water, or around 212F at sea level. In an unpressurized pot, the water in the food will turn to steam and escape the food as the temperature exceeds this, taking much of the heat with it. This slows the cooking rate significantly, and it can dry the inside and affect the structure of the food.

In a pressure cooker, the sealed and pressurized environment actually increases the boiling point of water. On an electric pressure cooker or an instant pot, this can move the boiling point all the way to 250F or more. Water within the food can get much hotter before steaming away. That means the moisture stays inside the food and continues the cooking. In a non-pressurized pot, the moisture can exit the food and make it more difficult to conduct the heat to the internal parts of the food. This slows a traditional cooker’s cook-time, which is much of the reason a pressure cooker is faster.

A huge advantage to cooking in a pressure cooker is that your food will be much moister. It can also allow your food to retain more nutrients because of this, though there is some contention on this point between experts.

What Foods Are Pressure Cookers Suitable For?

Pressure cookers do a lot of things right. They shorten the cook time for many foods, keep your food moist, and help to maintain nutrients in the food. Overall, they are great tools for any cook to have in their kitchen.

That is not to say they are the right or best way to cook everything. There are some foods that simply don’t work well and others perfectly suited for pressure cooking.

Which Foods Work Well In Pressure Cookers?

Pressure cookers are great at cooking certain foods. They work well for foods that taste great boiled or braised, and for foods that have a high moisture content.


Most meats turn out great in pressure cookers. This is especially true for ribs, roast, and whole chicken. Just follow the recommended procedure in the recipe book included with your cooker or other recipes designed specifically for pressure cookers and instant pots. 

Part of the reason pressure cookers work so well with meat is the high temperature, which helps to break down the tough connective tissues and tenderize the meat. The meat will end up moist, tender, and even cooked, and it’ll take far less time than other cooking methods.


Soups of all kinds work fantastic in a pressure cooker. They cook in a short time and lose less nutrients. Pressure cooking also helps soften some of the tougher ingredients, such as meats, potatoes, and carrots. 

Liquid in soup does not steam away in a pressure cooker like it does on a stove. Because of that, you can put only the final amount of liquid in the pot. You can season the soup properly at the beginning, knowing the soup will not concentrate down. This makes it much easier to get the proper flavor.


Rice cooks very quickly in a pressure cooker, even quicker than a rice cooker in many cases. Some pressure cookers even have a rice mode. Pressure cooker rice ends up fluffy and soft, and it works equally well for white rice and brown rice. 

With a pressure cooker, the water does not steam away. Many rice cooker and stovetop methods require you to add a bit of extra water to allow for this escaped steam. The pressure also forces water into your rice. This means most pressure cooker rice recipes call directly for an equal amount of water and rice. With experience, you’ll learn to adjust the water level to suit your desired firmness, using less if you prefer firm rice.


Vegetables of all kinds cook great in a pressure cooker. It’s an especially good way to cook potatoes, carrots, beets, corn on the cob, and tougher vegetables. The pressure cooker will soften the harder veggies. Your vegetables will also have more nutrients and better flavor because of the shorter cook time.


Beans turn out great in a pressure cooker. Like the foods above, they’ll retain more flavor and nutrients. As an added benefit, you do not need to pre soak the beans before cooking, which can save a lot of time. If you do it properly and follow one of the pressure cooker bean recipes, your beans will be terrific in the end.

Which Foods Do Not Work Well In Pressure Cookers?

It would be great if you could put everything in the pressure cooker and get a quick meal, but that’s just not how it works. Some foods are not well suited to the pressure, while other foods have problems with the amount of moisture necessary for pressure cooking. 

Anything Crispy

Pressure cookers add moisture to your food, which typically is the enemy of a good crisp on the food surface. They aren’t fryers, so they won’t cook that outside edge or breading. In fact, breading usually falls off in the cooker. Oils won’t reach the proper temperature to actually fry anything. The pressure and moisture is going to create a tender food, but your crispiness will go away as it cooks.

If you make breaded or crispy foods often and you also use a pressure cooker, then a multi-cooker with an air fryer lid attachment may work well for you. That allows the multi-cooker to operate in pressure cooker mode when you need a pressure cooker, but still lets you use the air fryer lid to make breaded and crispy foods.


Fish is very delicate, and you need to be careful with the cooking time. You cannot monitor the doneness of the fish and remove it from the cooker when done, but if you cook it even a few seconds too long it could ruin it. Because fish is so picky and you have to watch it so carefully, you’re better off not pressure cooking it.


Steak won’t reach the right temperature to brown the outside. There will be no sear, no caramelization, and little flavor. Like fish, it’s also hard to remove it at just the right temperature. This applies to delicate meats like tenderloin as well. Just don’t use a pressure cooker for it, it isn’t the right tool for the job.


There are certain foods, like noodles and applesauce, that you shouldn’t cook in a pressure cooker. While you can do it, and you’ll find a lot of recipes for pressure cooker noodles, it isn’t a good idea. The food can foam up, cause the steam vent to sputter out moisture, or clog up your vent. It’s just going to be a mess, and your noodles may cook unevenly or come out gummy. You’re better off cooking your pasta on the stove, and it’s just as quick. 


You don’t want to try to use a pressure cooker for light and fluffy foods like pastries. Pastries are going to end up a soggy mess, because the pressure cooker uses steam and moisture to cook. You’re just going to destroy your pastry, so don’t try it.

Does Altitude Affect How A Pressure Cooker Works?

Altitude affects cooking times because of atmospheric pressure. This applies to all kinds of cooking, even pressure cookers. 

As you go higher atmospheric pressure drops, which lowers the boiling point of water and makes it easier for water to steam away.  For example, water boils at 202F a mile up in Denver, Colorado, but boils at 212F when at sea level in Miami, Florida. This means you must extend the cook time, sometimes by as much as twenty percent or more. Higher altitudes also tend to be dryer, so your foods lose more moisture while cooking. 

Pressure cookers prevent a lot of that. While they do cook slightly slower at high altitudes than they do at lower altitudes, they still cook much faster than other forms of cooking. This is because of lower absolute pressure inside, which is the atmospheric pressure + the pressure inside the cooker. They also, by the nature of the pressurized and sealed system, do a better job of keeping the food moist. Because of this, many people find a pressure cooker indispensable at higher elevations.

Can I Use A Pressure Cooker For Canning?

Many people would love to use their pressure cooker for canning, but they are not the same thing as pressure canners. Pressure canners are much larger and do a better job of ensuring the proper pressure and heat is reached inside each jar.

That isn’t to say a pressure cooker cannot be used for canning, you just have to be careful about what you can in it. Many newer cookers, like the Instant Pot Max, have canning modes. Despite this, the USDA doesn’t recommend it. The main culprit in home canning is bacteria, and specifically clostridium botulinum. Instant pots can’t get to the right pressure and temperature combination to kill it. 

The good news is that you can use a pressure cooker for canning highly acidic foods. Acid kills off the bacteria, so your fruits are good to go. You can safely use your Instant Pot Max for tomatoes or pickles. If, despite the USDA not considering it safe, you decide to can low acid foods like meat or vegetables, always make certain you use the high pressure setting if multiple settings are available. 

Note that canning tomatoes is typically safe, but you should check the acid level of your tomatoes. Some tomatoes have too high of a ph level to kill off bacteria safely. If your ph level is above 4.6, consider adding vinegar or citric acid with the tomatoes until reaching a lower ph. This will make the mixture acidic enough for safe canning in a pressure cooker.

Are Pressure Cookers Safe?

In the past, it was common to hear stories of exploding pressure cookers. People would wind up hurt, with food on their ceiling, or a mess on their stove. This was because older models didn’t have any safety valves. If their pressure regulator and steam vent became plugged the unit could continue to build pressure beyond levels the pot could contain. 

Can A Modern Pressure Cooker Explode?

Any modern pressure cooker should be extremely safe to use. Modern cookers have at least one safety valve. Generally speaking, the pressure regulator and steam vent should let any pressure beyond normal limits escape from the pot. If your pot ever exceeds that limit, the safety valve or valves should open and release the pressure. This prevents it from ever reaching the level where it could explode.

To make sure your cooker is as safe as it can be, make sure to clean it as described by the manufacturer. Be certain your steam release valve is free of debris, and be sure to inspect your cooker before each use to be sure all seals are in good shape and there is no damage to your unit. These simple steps can greatly improve the safety of an already extremely safe countertop appliance.

Is Pressure Cooking Bad For Your Health?

No, pressure cooking is not bad for your health. All methods of cooking damage the vitamins and healthy fats within the food. Overall, it appears that pressure cooking is no worse than any other method of cooking, and in some cases better. When you use a pressure cooker you avoid the added oils from frying. You also have a shorter cooking time than other types of cooking, such as baking, which means less time cooking and less time breaking down vitamins and nutrients.

The Dangers Of Steam

This is an area where pressure cookers can be dangerous if you do not take care. There are a lot of safety features built into pressure cookers, but many of them still have a relief valve that you can manually open to release the pressure inside, which in turn lets out a lot of hot steam. If you are not careful you could get a steam burn. 

The most likely time that you could get a steam burn from a pressure cooker is when releasing the steam from the pot manually. This is when you turn the venting knob from the sealing position to venting. That could release a burst of hot steam if the pot has not sufficiently cooled. If your hand, arm, or other body part are over the vent at the time, you could get a burn. You can avoid a steam burn by using caution when releasing pressure early in this manner.

What Is An Instant Pot Water Test?

An instant pot water test, also called a pressure cooker water test, is a quick and easy test run for your pressure cooker. It is especially helpful if it is the first run on a new cooker or the first time you’ve used a pressure cooker. The test is a way to familiarize yourself with how the cooker works, helps to make sure all the seals are in place and working properly and safely, and does a quick cleaning of the inside of the instant pot if this is its first use. 

Follow these steps to perform a water test

  1. Place the inner pot into your cooker.
  2. Add 3 cups of water.
  3. Close and lock the lid.
  4. Rotate the vent knob to the sealed position, if this applies to your mode of cooker
  5. Press the “pressure cook” button on your system.
  6. Set the cooking time to 3 minutes.
  7. The instant pot should come on and go into the preheating & pressurizing stage, which will take several minutes. You may see some steam coming from the steam valve or floating valve at this point. That is normal.
  8. Once the cooker completes the preheating stage your cooker will switch to cook mode and you should see the timer begin to count down.
  9. Your cooker may switch into a warming mode when the timer reaches zero. If it does, turn your instant pot off.
  10. The last step is to release the steam using the steam release valve following the instructions from your manufacturer.

If you reached this point and haven’t seen any problems, your cooker passed the water test. But if you notice any of these signs below, your cooker failed the water test.

  • You notice steam coming from around the lid
  • The cooker never reached pressure
  • You saw excessive amounts of steam rising from the steam valve

Steam rising from the steam valve or the float valve is normal during the test, but should mostly stop when it reaches the cook stage. If it continues to release steam and never pressurizes, you could have a dirty or stuck valve. Check the valve to make sure there is no debris in it, then clean it. You may need to work the valves a few times to open things up. At that point, your cooker should work properly if this was the problem.

If the cooker never reaches pressure, check the lid. This can happen if you did not properly close the lid or your steam valve is not in the vent position. You could also have a damaged silicone seal ring that sits between the lid and the rest of the cooker.

The silicone seal is the sealing ring you see around the bottom of the lid on your pressure cooker. It is made of high quality silicone. These rings are important to ensure there is a proper seal between your cooker and the lid. If yours goes bad or damaged you may see steam emanating from the outside edge of the lid. This can also happen if your seal is dirty or wet, so be sure it is clean and dry before using your cooker.

You can buy replacement seals from places like Amazon, Target, and Best Buy. Always make sure to use the OEM replacement rings directly from the manufacturer or you may end up with a void warranty or a seal that doesn’t perform properly.

Silicone rings are easy to clean. On most cookers the ring simply presses into the lid. You can carefully tug it away from the lid and clean it with dish liquid and a sponge. To reinstall it you press it back into the lid and it should stay in place. If you have any problems removing or installing, consult the manual for your cooker.

Your silicone ring may become smelly over time. This is because the silicone absorbs some of the odor from your foods as you cook. You can sometimes remove this odor by soaking the silicone ring in a solution of water and vinegar.

Silicone rings can become damaged or worn over time. You should usually plan to replace yours about once a year. Also replace the seal if you notice any damage or the seal no longer is sealing properly. Check your manual and follow the recommended replacement schedule you find there. 

Hidden Features

A lot of pressure cookers have features you may not think about or even notice. One of these hidden features is the three-ply base in the inner pot. This is typically a stainless steel inside and outside layer with a layer of aluminum in between. The reason for this is head conduction. Aluminum transfers heat better, so it helps your inner pot heat evenly. But aluminum reacts with some foods, so they sandwich it between the less reactive stainless steel.

Many pressure cookers also have a flexible plate under the base that bends as it gets hot. When the cooker reaches the proper temperature, the flexible plate bends against a switch that turns the heat off. It’ll then lose contact as it cools, causing the switch to turn the heat back on.

Most pressure cookers have a couple of safety features in the lid that are not all that obvious. One of these is a locking mechanism that prevents you from opening the pot when pressurized. Another safety feature is a sensor that prevents the cooker from turning on if you didn’t properly attach the lid.

Another feature you may not notice involves the steam release. There is a small shield below it designed to prevent food from clogging it up. A clogged steam vent may not open properly if it is clogged, so this is a very important safety feature.

Cookers also have a release mechanism that involves the silicone ring gasket. If the unit becomes overpressurized, the gasket pushes away and allows pressure to release through an aperture.

Overall, cooking with a pressure cooker is quite safe. Your food should come out tasty and at least as nutritious as with any other cooking method, and there are many safety features built-in to protect a user.

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