Pressure cookers: how they work

In short: A pressure cooker is a tightly sealed pot in which overpressure builds up as it is heated. Under this pressure, water only boils well above 100 °C, which is why food cooks faster.

In more detail: Depending on the cooking setting, the water in the pot reaches roughly 110 to 120 °C. Several valves and a lid lock make sure the pressure stays limited and the pot can only be opened once it is depressurised.

In detail

• Physical principle: The boiling point of water depends on pressure; when the pressure in the closed pot rises, so does the temperature at which the water boils.
• Seal: A rubber ring between pot and lid keeps the steam inside; it should be clean, supple and undamaged and replaced from time to time.
• Cooking valve: An indicator or valve in the lid shows the pressure and lets off excess steam, so the chosen cooking setting is maintained.
• Safety valves: Additional safety devices release steam if the main valve is blocked; that is why all valves must be clear and clean before every use.
• Filling level: Never fill the pot above the marked maximum; for foods that foam or swell a lot, such as pulses or rice, a lower limit applies according to the instructions.
• Only open without pressure: Never force the lid open; first release the pressure, for example by letting it cool or using the intended release function, and keep your face and hands away from the escaping steam.
• Energy and time: Because cooking times are often much shorter, a pressure cooker usually uses less energy than an ordinary pot, especially for potatoes, pulses or stews.
• Electric versions: Electric pressure cookers regulate pressure and temperature themselves; here too, follow the instructions and never open a damaged device yourself (energiesparen-beim-kochen-und-backen, backofen-funktionsweise).