The principle of pressure cooking is really quite simple. A pressure cooker is airtight, so pressure builds up inside the pressure cooker as the liquid inside comes to a boil. The resulting trapped steam causes the internal temperature to rise beyond what it would be capable of doing under normal room pressure. Then, put simply, the food is cooking at a higher temperature and under pressure so cooks faster.
At sea level (where the normal atmospheric pressure is 14.7 pounds per square inch), the boiling point of water is 100° C, the highest temperature which can be reached by water at that elevation. That boiling point is raised 3.3° C to 121° C under the 15 additional pounds of pressure that can be obtained in a pressure cooker. Foods cooked hotter cook faster.
A secondary benefit of the increased pressure is that it softens the fibres in foods, tenderising even the toughest of meats and beans. The increased internal temperature and the assault on the fibrous nature of foods cooked under pressure combine to decrease by two-thirds or more of the normal cooking times.
The DUROMATIC pressure cookers belong to the new generation of pressure cookers. They are built with safety features that make it impossible for a disaster to occur.
First, the automatic lid-locking device of the DUROMATIC pressure cookers ensures that no pressure can build up until the lid is put on correctly. The lid cannot be removed or come off until all of the pressure has been released.
DUROMATIC pressure cookers provide the ultimate protection against excess pressure. The first indication that too much pressure has built up inside the cooker is the audible hiss of the valve as excess pressure is released through the valve. When the user hears this, the heat should be turned down. As long as the valve is not clogged, it will take care of any over pressurisation by allowing steam to escape through the radial escape holes located on the valve stem.
Other safety releases will come into effect only if the central valve is clogged. If that occurs excess pressure will also escape through the safety holes in the rim of the lid.
Additionally, another spring-loaded safety valve in the lid is set to release steam in case of a clogged main valve due to overfilling or too-high heat. This valve is not a "blow plug" like some old American cookers had, but a highly accurate spring-loaded valve which will open at a pre-set internal pressure and release steam safely and effectively.
Finally, at higher pressure, the gasket is forced out through the six bayonet flanges in the lid, and a jet of excess steam escapes (once again in a downward direction.)
There are three methods for releasing the pressure in your cooker. Recipes will indicate which release method to use at the end of the cooking process.
1. Touch Release (Quick Release) Method - The valve on the lid of the DUROMATIC pressure cooker releases the pressure quickly by a light finger touch or, if you prefer, you can use a long-handled spoon or spatula to depress the insulated, black valve cap. This method is suggested if you wish to interrupt the cooking process in order to add some further ingredients. By releasing the steam this way you can quickly open the pressure cooker without cooling off the pot and stopping the cooking process. Do not use this method for food that foams and is cooked on the first red ring.
2. Cold Water Release Method - If a quicker release of pressure is desired, the pan can be carried to the sink and cold water may be run over the lid (but not the valve). This method is mainly used for food with short cooking times where it is essential to stop the cooking process as fast as possible. For example risotto, polenta, or fresh vegetables. Do not use this method for food that foams (rice, beans, and stocks) or is cooked on the first red ring.
3. Natural Release Method - A third method of releasing the pressure is to remove the pressure cooker from the heat source and to allow the pressure to subside naturally. This is the preferred method if you are cooking beans, potatoes, or other foods that have a skin that you wish to remain intact. The time it takes to release the pressure in this manner is calculated into all pressure cooker recipes.
Place the lid upside down on the pan for storage, so that there is no stress on the ring seal in the lid and all components are well ventilated.
You may wish to place a towel between the lid and the pan in order to protect the finish from scratches.
Kuhn Rikon combines the excellent qualities of stainless steel with the superior heat conductivity of aluminium to obtain cookware with the benefits of both metals.
First, the stainless steel pan is formed, then a 7mm / ¼" thick disc of aluminium is attached. A disc of stainless steel completes the "sandwich" on the bottom of the pan. This final stainless steel disc is attached because it creates a more aesthetically pleasing piece and because stainless steel, being smoother and less porous than aluminium, is easier to clean and is non-abrasive to ceramic cook tops.
The aluminium never touches the food being cooked.