Pressure cooker is used for pressure cooking which is a method of cooking in a sealed pot that does not allow air or liquid to escape below a preset pressure. Pressure cooking is often used to simulate the effects of long braising or simmering in shorter periods of time.  As the pressure rises, the boiling point of water increases.  The pressure built up inside the pot lets the liquid to rise to a higher temperature before boiling.  When boiling, the pressure is created inside the closed pressure cooker.  The trapped steam increases the internal pressure and temperature.  This causes wet steam to be forced through the food and results in faster cooking times.  Afterwards, the pressure is slowly released so that the pot can be safely opened. 

Pressure Cooking with Pressure Cooker

Pressure cookers are generally made of aluminum or stainless steel.  High quality stainless steel pressure cookers are made with heavy, tri-ply, or copper-clad bottoms for high heat conduction.  Some pressure cookers have non-stick interior.  In order to prevent the air or steam escaping between the pot and lid, a gasket or sealing ring is in place to form a gas-tight seal.  In some models, it is featured a metal-to-metal seal.  Because of the forces they have to withstand, pressure cookers are usually heavier than normal pots of similar size.

Food is cooked much faster with pressure cooking method.  However, a minimum quantity of liquid is required to create and maintain pressure.  Also, pressure cooker should never be filled to more than 2/3 the interior height with solid food, half full for liquid and foods that foam and froth such as rice, pasta, etc., and no more than 1/3 full for pulses such as lentils.  A tablespoon of cooking oil can be added to minimize the foaming.  Because less water is required when cooking with pressure cooker, vitamins and minerals are not dissolved away by water.  Due to the shorter cooking time, vitamins are preserved relatively well during pressure cooking.

Pressure Cooking with Pressure Cooker

Pressure cooking with pressure cooker helps food cooked faster than conventional cooking methods.  Food can be prepared in a shorter period of time and preserved vitamins and minerals.