Editing Pressure cooker (section)

=== Bringing to pressure ===

The lid is closed, the pressure setting is chosen and the pressure cooker is heated to boil the liquid. The cooker fills with steam and vents air. As the internal temperature rises, the pressure rises until it reaches the desired [[gauge pressure]].

It usually takes several minutes for the pressure cooker to reach the selected pressure level. It can take 10 minutes or longer depending on the quantity of food, the temperature of the food (cold or frozen food delays pressurization), the amount of liquid, the power of the heat source, and the size of the pressure cooker. There is typically a pop-up indicator that shows that the cooker has pressure inside, but it does not reliably signal that the cooker has reached the selected pressure. The pop-up indicator shows the state of the interlock which prevents the lid from being opened while there is any internal pressure. Manufacturers may use their own terminology for this, such as calling it a ''"locking indicator."''

Timing the recipe begins when the selected pressure/pressure is reached. Once the cooker reaches full pressure, the heat is lowered to maintain the pressure. With pressure cookers accurate timing is essential using an audible [[timer]].

With first generation designs, the pressure regulator weight begins levitating above its [[nozzle]], allowing excess steam to escape. In second generation pressure cookers, either a [[relief valve]] subsequently opens, releasing steam to prevent the pressure from rising any further or a rod rises with markers to indicate the pressure level, without constantly venting steam. At this stage, the heat source is reduced to the lowest possible heat that still maintains pressure, as extra heat wastes energy and increases liquid loss. In third generation pressure cookers, the device will detect the vessel has reached the required cooking temperature/pressure and will maintain it for the programmed time, generally without further loss of steam.

Recipes for foods using [[Leavening agent|raising agents]] such as steamed puddings call for gentle pre-steaming, without pressure, in order to activate the raising agents prior to cooking and achieve a light, fluffy texture.