To understand how a pressure cooker works, you need to know just a little about physics. Simply put, water boils
at 212o Farenheit.
At this point, no matter how long you continue to
boil, it always stays the same temperature. As the water evaporates and becomes
steam it is also the same temperature, 212o F.
Why isn't the food pulverized? It's all in the physics: As long as pressure is
uniform on all surfaces of an object, it won't be distorted.
Pressure is effective throughout the food items, from the surface through to the center! No matter whether you're cooking a single chicken breast,or a 5-pound ham.
only way to make the steam hotter (and/or to boil the water at a higher
temperature) is to put the system under pressure. This is what a
pressure cooker does. If
we fit an absolutely tight cover to the pan
so no steam can escape while
we continue to add heat,
both the pressure and temperature inside the
vessel will rise. The steam
and water will both
increase in temperature and pressure, and each
fluid will be at the same temperature and pressure
as the other.
has six times the heat potential when it condenses on a cool food product. This increased heat transfer
potential is why steam is such an effective cooking medium.
If you put water into a pot and cover it with a tightly sealed lid, the steam will remain
trapped and pressure will build and that rises the temperature at which the liquid boils. So at 15psi your
food is cooking at 257oF
of just 212oF. When you turn off the heat and begin to
drop the pressure you will sometimes hear the food begin to boil
inside the closed pot as the pressure drops
and the contents come back down to the normal
boiling temperature. See more about pressure
Pressure cookers are especially designed cookware of aluminum or stainless steel. All models have a lock-on
lid and a vent or pressure relief valve. Most pressure cookers are designed to be used on top of your stove,
but there are some electrical models and also a one that is supposed to work in the microwave.
Food is cooked by the high temperatures inside the cooker. Click
here to see how the internal pressure compares
to temperatures. This high temperature is made possible by raising
the pressure to a point greater than atmospheric pressure. Cooking times are based on pounds of pressure.