What Is Pressure Cooking and How Does It Work?

updated Jan 14, 2021
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Credit: Joe Lingeman

By now, you’ve certainly heard of the Instant Pot. (Especially if you’re a fan of this site.) There are several different models, dozens of devoted Facebook groups, and countless cookbooks related to Instant Pot cooking. But before there were electric pressure cookers, there were stovetop pressure cookers. Both have their merits and, here, we’re going to go over some pressure cooking basics, no matter what kind of pressure cooker you’re into.

What is a pressure cooker? How does it work? What can you make it with it? Keep reading and we’ll answer all your questions.

What is a pressure cooker, and what does it do?

A pressure cooker works on a simple principle: Steam pressure. A sealed pot, with a lot of steam inside, builds up high pressure, which helps food cook faster.

When was the pressure cooker invented?

It was invented in the 1600s by a Frenchman by Denis Papin, who wanted to translate new discoveries in physics about pressure and steam into cooking. He called his pot the “Digester,” but it took quite a while before better manufacturing standards and technology could make these high pressure pots safe.

How does a pressure cooker work?

A pressure cooker is a sealed pot with a valve that controls the steam pressure inside. As the pot heats up, the liquid inside forms steam, which raises the pressure in the pot. This high pressure steam has two major effects:

1. Raises the boiling point of the water in the pot

When cooking something wet, like a stew or steamed vegetables, the heat of your cooking is limited to the boiling point of water (212°F). But with the steam’s pressure now the boiling point can get as high as 250°F. This higher heat helps the food to cook faster.

2. Raises the pressure, forcing liquid into the food

The high pressure also helps force liquid and moisture into the food quickly, which helps it cook faster and also helps certain foods, like tough meat, get very tender very quickly.

The extra-high heat of the pressure cooker also promotes caramelization and browning in a surprising way — we’re not used to food caramelizing when it is cooking in liquid. But the flavors created in a pressure cooker can be really deep and complex, unlike regular steamed foods.

For a closer look at a pressure cooker in action, check out this article from Modernist Cuisine.

Credit: Photo: Joe Lingeman; Food Styling: Brett Regot
Hard boiled eggs on the stove top? Nah, hard boiled eggs in the Instant Pot are faster!

What can you cook in the pressure cooker?

Almost anything! It cooks rice in just a few minutes, and it cooks tougher things like beans and chickpeas in much less than an hour. It is very good for foods that need to be tenderized like braised meats and roasts. But people have cooked all kinds of other things in it, too, like hard or soft boiled eggs. But it is used most frequently around the world for beans and pulses, stews, and vegetables.

What’s tricky about cooking in a pressure cooker?

It’s a whole new way of cooking, with its own language and processes. You usually need to wait for a pressure cooker to heat up, then you add the food and the lid, and let it cook for a certain amount of time, at a certain pressure level. (How long? There are many pressure cooking charts that show you how long certain foods should cook — I use the one that came with my electric pressure cooker.) Then you let the pressure release (sometimes fast, sometimes slow — depends on the recipe).

In all of this, your instincts as a cook are not always helpful. We know how to sauté, how to brown meat, how to boil potatoes. But a pressure cooker is a sealed box — you can’t touch or taste the food as it is cooking, and successful pressure cooking relies on a new bank of knowledge that most of us have to acquire.

What’s pretty great about the pressure cooker?

But is it worth it? I think so, for many people. The pressure cooker is highly efficient — it uses far less energy than many other appliances, since it cooks so quickly and leverages the pressure powers of steam. Last week I made the most tender, falling-apart lamb curry I’ve ever had, with the flavors of the spices saturating the meat. I also made chickpeas from scratch in 45 minutes, and spiced rice in 6 minutes.

And now, with electric pressure cookers, like the Instant Pot, pressure cooking is even simpler. These types of pressure cookers have built-in safety mechanisms that take a lot of the anxieties you may have about pressure cooking out the equation. They also have presets options for rice, beans, and broth, so you don’t have to guess or even look in the manual for how long to cook things.

Both stovetop and electric pressure cookers really should be called fast cookers —they’re fascinating tools and good for many, many dishes in the kitchen.

What questions do you have about pressure cookers? Leave them in the comments below!