Pressure Steaming
What it is
Steaming (or moist cooking generally) inside a sealed pressure vessel, where trapped steam raises the internal pressure and, with it, the boiling point of water — so the food cooks in steam hotter than 100 °C, typically around 121 °C (250 °F) at the standard 15 psi above atmospheric. The pressure cooker (and the industrial autoclave/retort) is the tool.
The science
Recall that water boils when its vapor pressure equals the surrounding pressure. Seal the pot and let steam build, and the pressure climbs; the higher pressure means water can't boil until it's hotter, so the whole moist environment can exceed the normal 100 °C ceiling. At 15 psi gauge, water boils near 121 °C. This higher temperature accelerates every heat-driven reaction: collagen-to-gelatin conversion that takes hours at a braise happens in a fraction of the time; dried beans and tough grains soften far faster; starch gelatinizes quickly and thoroughly; and even some Maillard-style browning and caramelization can occur in the pressurized moist environment (which is why pressure-cooked stocks and stews can develop a surprising roasted depth). It's also the basis of canning safety: only a pressure canner reaches the ~121 °C needed to reliably destroy Clostridium botulinum spores in low-acid foods — boiling-water canning at 100 °C cannot. The trade-off is loss of control and sight: you can't see, stir, or taste mid-cook, and the elevated heat can overcook delicate items in seconds.
How it's done
Add food and the required minimum liquid (steam needs water to form), seal the lid, bring up to pressure over high heat, then reduce heat to maintain pressure for the (much shorter) cook time. Release pressure either naturally (let it fall as it cools — gentler, good for meats and beans) or quickly (vent it — to stop cooking fast, good for vegetables). Modern electric multicookers automate the pressure regulation.
When to use it
For long-cooking foods you want done fast: tough braising cuts, beans and legumes, stocks and bone broths (hours compressed into one), tough grains, and risotto-style dishes; for high-altitude kitchens where the low boiling point otherwise makes cooking painfully slow (pressure restores a high cooking temperature); and for safe canning of low-acid foods. Choose it over open braising/steaming when speed and energy efficiency matter more than moment-to-moment control or browning.
What goes wrong
Too little liquid (no steam, scorching, or a safety lockout). Overcooking — at this speed, delicate items go from perfect to mush in moments, so timing and quick-release discipline are critical. Overfilling foamy foods (beans, grains) that can clog the vent. The old folk fear of explosions belongs largely to mid-century devices; modern cookers have multiple redundant safety interlocks, though pressure must never be force-opened. For canning, using a boiling-water bath for low-acid foods (a genuine botulism hazard) instead of a pressure canner.
Regional & cultural variations
The pressure cooker is a near-universal modern kitchen staple but is especially beloved in Indian cooking, where it's the default for dals, beans, and meats — the rhythmic whistle (seeti) of the pressure cooker is the sound of countless home kitchens, and recipes are timed in whistles. It's essential in the high Andes and Himalaya, where altitude makes ordinary boiling ineffective. Latin American kitchens lean on it for beans; East Asian and global home cooks have adopted electric multicookers widely.
Cultural & historical context
The pressure principle was demonstrated by Denis Papin's "steam digester" in 1679; the domestic pressure cooker spread in the 20th century, surging during wartime fuel rationing as a way to cook tough, cheap food fast with little energy. Its adoption in India and high-altitude regions shows how a single device reshaped daily cooking where fuel was scarce or altitude was an obstacle.
Reference notes
The high-pressure extension of Direct Steaming and a turbo version of Braising & Stewing; cross-link to Boiling and the altitude/pressure discussion (Foundations), to collagen-to-gelatin conversion (vastly accelerated), to canning/preservation safety, to Indian dal cookery, and to the multicooker vessel. The inverse of high-altitude boiling: pressure raises the ceiling that altitude lowers.