A pressure cooker has a modified lid that locks on over a rubber gasket to create a seal. The cooker works by raising the temperature of boiling water, thereby speeding up the time it takes to boil, braise, or steam.
Pressure cookers work by raising the internal pressure of the pot to speed up cooking times. This is done by using water or broth and sealing it in an air tight pot. As the liquid is heated, it boils and converts to steam. As steam builds, pressure increases, driving the boiling point of water past 212°F.
The trapped steam increases the atmospheric pressure inside the cooker by 15 pounds per square inch (psi), or 15 pounds above normal sea-level pressure.
The steam also keeps the food moist, therefore this device is perfect for meat stews, mashed potatoes and even cheesecakes.
The pressure trapped pressure reduces the cooking time because the water reaches its boiling quicker and at a lower temperature. Also, the heated steam is forced deeper into the food because of the higher pressure, making it cook faster without burning food.
And, because the vessel is sealed, it also limits evaporation of critical volatile flavor and aroma compounds. An added plus: the contents of a pressure cooker go relatively undisturbed, since the liquid never effectively boils.
Pressure cooker -How it works?
