Sunday, June 9, 2013

How Pressure Cookers work?

Simpler, easier, quicker ---the thirst to combine the trio in many aspects can lead to inventions.  One such invention is ‘’Pressure cooker’’ Since it has become the part of our day-to-day life it may not appear interesting to many... The science behind the pressure cooker is simple but interesting. What makes this pot so special?? Yes it is the Pressure (P). We all know at normal environmental conditions water boils at 100 °C, excess heat results in vaporization of water into steam.
In case of pressure cooker, food is added along with little amount of water inside the cooker. As it’s a closed environment steam produced cannot escape. Thus produced steam increases the pressure inside the cooker by 15 pounds per square inch (psi), and temperature also increased. Water boils at 121 °C. Higher temperature results in faster cooking. When cooker reaches high pressure (15 psi in most of the cookers) release valve opens in the lid allowing steam to escape and maintaining constant temperature inside.
Autoclaves that are used in hospitals and laboratories for the purpose of sterilization works under the same principle. Pressure cooking is faster than conventional cooking methods. Most of the microorganisms are killed as food is being cooked at the temperature above the melting point. Due to the little water in food, vitamins, minerals and the aroma is preserved to higher extent. Due to the little water in food, vitamins, minerals and the aroma is preserved to higher extent. On the other hand   checking of doneness is not so simple in pressure cooker. Little more time will result in overcooking.
Pressure cookers are boon at high altitudes. Due to low air pressure water boils soon. So it’s difficult to increase water temperature for cooking hence cooking is time consuming. Since pressure cooker is closed system it’s convenient to cook using it at higher altitude. Big salute to Denis Papin -- the inventor of pressure cooker. There is always pleasure behind making things simpler...

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