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A pressure cooker doesn't allow for anything (even gases) to escape at any significant amounts (unless the pressure inside gets too high and you hear that whistleing noise).
With heat, the gases inside want to expand, but because they are restricted to the volume of the pressure cooker they can't, so pressure builds up.
In addition, when a liquid, lets say water in this case, is heated under normal pressure its temperature won't go above 100C, because any water molecule that has higher energy leaves the liquid and goes into gas phase.
Now, applying pressure to water, will increase the boiling point (for example from 100C to 110C)
Reason: When any liquid is under higher pressure it is less likely to go in the gaseous phase.
The pressure cooker works with these principles, because usually when you cook water in an open pot, the boiling point of water restricts the temperature to a 100C. A pressure cooker uses the pressure to keep the water in the liquid form even though it is far above the boiling point, and hence the temperature is far above 100C.
Because the pressure build up inside causes higher cooking temperatures thus reducing cooking times.
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∙ 7y ago
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How much do cooking times change when using a pressure cooker instead of a normal pot?
Between cooking with a normal pot and a pressure cooker the difference in terms of time is not much. The pressure cooker can be used depending on the type of food that is cooked.
Where online can I read more about cooker pressure and find recipies for my presser cooker?
The website http://allrecipes.com//Recipes/everyday-cooking/pressure-cooker/Main.aspx has some great recipes available. They are easy to make and very simple when using the pressure cooker.
What are the benefits of a pressure cooker?
There are a select few benefits to using a pressure cooker. The benefits to using this device are as follows: healthy, efficient, safe and versatile.
Where can I find an instruction manual for Mirro pressure cooker?
http://www.redhillgeneralstore.com/pdf/mirromanual.pdf
Why is a pressure cooker used to cook at higher altitudes?
The boiling point of a liquid goes down as the atmospheric pressure decreases. At sea level water boils at 100 degrees C. As you go up higher the air pressure decreases (because there's less air above you). In 'mile high' Denver, Colorado, water boils at about 95 degrees C. Cooking, like all chemical reactions happens more slowly as the temperature decreases. Thus anything you cook by boiling will take longer at high altitudes. In a pressure cooker the pressure is higher than it is outside, so the water boils at a higher temperature and cooking times are reduced. In fact you don't have to live at high altitudes to benefit from using a pressure cooker. Even at sea level they are useful, especially for reducing the time for slow dishes such as stews, which is convenient and saves fuel.
What is the best pressure cooker to use if I want to fry chicken using one just like KFC?
the kipper cooker
What safety measures should be taken while using pressure cooker?
susan
Why pressure cooker is used for rapid cooking?
To know how a pressure cooker works you must know the physics behind it. The boiling point of water is 100°C. When boiling with in a pot with no cap, no matter how much you heat, it will never go past the temperature of 100°C because of evaporation. Also the vaporized steam is the same temperature of the boiling water. So when you cook with a pot of water this time with a sealed cap, as you try to add more heat by increasing the temp., all that will happen is that the vapor will try to escape but because it is a sealed environment it will not be able to escape resulting in the build up of pressure (or force/area). The temperature and pressure will have a direct proportional relationship so as one increase so does the other. Also steam has 6 times the heat potential when it condenses (changes from gas to liquid state of matter) on a cold food product. The build up of pressure and heat potential are two factors which enable pressure cookers to cook foods faster and more efficiently. In pressure cooker the pressure develops inside the vessel as time goes on. As pressure increases the boiling point of water also increases. Food inside the pressure cooker cooked very fast because of high boiling temperature, means the food is not cooked at 100 C but much higher temperature than 100 C. Rapid S Pressure cookers generally operate at 15psi (~760mmHg) above atmospheric pressure. Since atmospheric pressure is 14.7 psi, the pressure within the cooker is about double the atmospheric pressure. Once the operating pressure is attained, the temperature in the pot stabilizes at the boiling point for water at that pressure, which is about 120 C (248 F) at 2 atmospheres of pressure. Further temperature increase is prevented since the pressure is stabilized by the constant venting of steam from the cooking vessel. If the temperature is raised by only 20 C above open pot boiling, why is the cooking time so much faster? The answer is that cooking results from chemical reactions in the food, and the rate at which all chemical reactions occur depends on the temperature. The temperature dependence of reactions is variable, but a rough rule of thumb is that the rate will double for every 10 C increase in temperature. Therefore the reactions that occur during cooking will occur roughly 4 times faster in a pressure cooker at 120 C, and the food will cook in one quarter of the time.
Can dulce de leche be made in a pressure cooker?
Dulce De Leche can be purchased ready made or if using a can of condensed milk can be placed in a pressure cooker for 45 minutes.
How does using a pressure cooker preserve the nutritional value of food?
it does not allow the nutrients to escape
How using a pressure cooker preserve the nutritional value of food?
it does not allow the nutrients to escape
How do pressure cookers work?
the boiling point increases with increase in pressure
