Pressure cooker

A pressure cooker is a sealed pot that cooks food using high-pressure steam from water or a water-based liquid, a method known as pressure cooking. By raising the pressure, it prevents boiling and allows temperatures to climb higher than normal, which cooks food much faster. The forerunner of today’s pressure cooker was the steam digester, created in the 1600s by physicist Denis Papin. The device works by pushing air out of the pot and trapping the steam produced when the liquid boils.

Theory

This raises the internal pressure to about one atmosphere above the surrounding air, yielding cooking temperatures between 100–121 °C (212–250 °F). Combined with the efficient heat transfer of steam, it can cut cooking time to between half and a quarter of conventional boiling, also saving a good deal of energy. Nearly any food that can be cooked in steam or water-based liquids works in a pressure cooker. Modern models include many safety features to prevent dangerous pressure levels that could cause an explosion.

After cooking, the steam pressure is released back to normal so the pot can be opened, and a safety lock prevents opening while it is still under pressure. In 1950, 37% of U.S. households owned a pressure cooker, according to The New York Times Magazine. By 2011, that figure had fallen to 20%. The drop is partly due to fears of explosions—though these are extremely rare with modern cookers—and competition from fast-cooking devices like microwave ovens.

However, third-generation pressure cookers, with more safety features, digital temperature control, no steam venting during cooking, and quieter, more efficient operation, have helped revive their popularity. In 1679, French physicist Denis Papin, known for his steam studies, invented the steam digester to shorten cooking times. His airtight cooker used steam pressure to raise water’s boiling point, making food cook faster. In 1681, he presented it to the Royal Society of London as a scientific study and was later elected a member.

History

In 1864, Georg Gutbrod of Stuttgart began making pressure cookers from tinned cast iron. Though pressurized steam cooking was known for two centuries, the term “pressure cooker” didn’t become common until the early 1900s. The earliest Oxford English Dictionary citation is from a 1914 Lincoln, Nebraska, newspaper, though Colorado newspapers from a few years earlier exist. By 1910, inventor Zeno E. Crook founded “The Pressure Cooker Company” in Denver, Colorado.

He developed an aluminum cooker for home use and marketed it to high-altitude communities in Colorado, where it worked well. Many hailed it as a new invention until 1918, when Popular Science Monthly revealed it was over 200 years old. In 1918, Spain granted a patent for the pressure cooker to José Alix Martínez of Zaragoza, who called it the olla exprés (“express cooking pot”), patent number 71143 in the Boletín Oficial de la Propiedad Industrial. In 1924, the first pressure cooker recipe book appeared, written by José Alix and titled 360 fórmulas de cocina Para guisar con la 'olla expres' (360 recipes for cooking with a pressure cooker).

In 1935, the Automa pressure cooker was introduced, and mountaineers climbing Mount Everest took it to cook at high altitudes. In 1938, Alfred Vischer presented his Flex-Seal Speed Cooker in New York City. It quickly became popular, sparking competition among American and European manufacturers. At the 1939 New York World’s Fair, the National Pressure Cooker Company (later National Presto Industries) introduced its own model.

First generation

Also called “old type” pressure cookers, these use a weight-modified or “jiggler” valve that releases pressure during operation. Some find them loud because the valve rattles as excess steam escapes. Older models usually offered only one pressure level, but from the 1960s onward, some let the operator change the valve’s weight to adjust pressure. Today, most pressure cookers are variations of first-generation designs, with added safety features like a lock that prevents opening until fully depressurized.

Second generation

These use a spring-loaded valve, often hidden in a proprietary mechanism, and typically offer two or more pressure settings. Some do not release steam during operation (non-venting) and instead have a rising indicator with markings to show pressure; they release steam only when opened or as a safety precaution if the heat isn’t reduced enough. Others have a dial that the operator clicks to change spring tension, adjusting pressure or releasing steam; these do vent steam during operation. Electric pressure cookers arrived in 1991, known as the “third generation.” They include an automatically regulated electric heat source.