What Is Pressure Cooking, and What Does It Do? A Pressure Cooker FAQ

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My own pressure cooker, an electric model from Cuisinart.

This week we've been teasing you with some pressure cooker posts — a discussion of your experience with this old-fashioned appliance, a peek inside a pressure cooker cookbook — but today we're going to get down to the basics. What is a pressure cooker anyway? When was it invented? How does it work? Why would you consider adding one to your arsenal of kitchen tools?

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The Marmite de Papin, an early pressure cooker prototype, at Musée des Arts et Métiers in Paris.

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.

A short video intended to show kids how pressure cooking works.

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 Modernist Cuisine:

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. Laura at Hip Pressure Cooking even made hard-boiled eggs (apparently the shells pop right off). 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.

The pressure cooker really should be called the fast cooker — it's a fascinating tool and good for many, many dishes in the kitchen.

We'll be bringing you more about the pressure cooker this week and next — recipes, how tos, pressure cooker reviews, and more! Is there anything in particular you'd like to learn?

(Images: Faith Durand)

More posts in this series

An Introduction to Pressure Cooking

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