How does a pressure cooker work?
Pressure cookers rely on some basic science you have to understand.
If you put a put of water on your stove, the water will reach 212 degrees Fahrenheit and boil. No matter how hard you try, you cannot get water raise the temperature any higher. It does not matter how high you set the heat on the stove or how long you let the water boil — it will never go above 212 degrees.
By raising the pressure on the water, you can get the water to go higher that 212 degrees. As the pressure rises, the boiling point or maximum temperature water will reach will also rise.
Water and steam also transfer heat much more efficiently than air does. Consider your oven — at 400 degrees you can reach into your oven without hurting yourself as long as you don’t touch anything and don’t leave your hand in there for a long time. However, if you reach into a boiling pot of water you will be scalded almost immediately. This demonstrates how much more efficient water is at transferring heat than air.
This is where the pressure cooker comes in. Just as boiling water will scald your hand quickly, boiling water and steam will transfer heat into the food quickly and efficiently.
This speed has two attractive points for cooking.
The first is obvious, meals can be prepared much faster than conventional cooking methods.
The second benefit is less obvious — food cooked quickly in a pressure cooker tends to be more healthy and flavorful than food cooked in an oven or on the stove top.
As the pressure cooker does its job, the cooker is sealed. This prevents nutrient rich steam from escaping into the air and this steam collects in the cooker itself. This flavorful steam will collect with the juices at the bottom of the cooker.