Normal water boils at 100 ° C at a pressure of 1 bar (= 100 kPa), the average air pressure at sea level. If boiling water once in an ordinary open pan (if the water has not evaporated), the temperature will not rise further. The extra added energy from the heat source (e.g., gas burner) provides evaporation of the water in the form of steam. It is a further waste of energy to allow the burner to burn harder than necessary to keep the water to the boil. By putting a lid on the heat loss is reduced and can be saved even more energy. There will always be escaping steam.
In a best pressure cooker‘s lid closed so that it can no longer just. The pressure will increase in the pan. The boiling point of water is dependent on the pressure. The higher the pressure, the higher the boiling point. Or vice versa; a lower pressure provides a lower boiling point. Hence, it ‘s hard to cook food in the mountains at high altitude without the pressure cooker.
Because of the closed lid, the temperature and pressure continue to increase the supply of sufficient heat (energy). That is, of course, undesirable if only because ultimately could crack the pan apart. For this reason, a pressure cooker has a pressure regulator. This is a type of valve that opens when the pressure comes above a particular value. This will cause hot steam and no further pressure rise. The pan continues to boil at the temperature corresponding to the boiling point of water at the appropriate pressure. Because the boiling temperature, the required cooking time will determine there since 1917 a standard pressure of about 103kPa (15 psi) above atmospheric pressure, set in America. The standard pressure in a pressure cooker is, therefore, more than double the normal air pressure at sea level. This allows for a cooking temperature of about 122 ° C. The specified cooking times in most cookbooks and recipes are based on this standard.
Modern pressure cookers still operate on the same fundamental principle. However, they have incorporated some additional safety features, such as an additional overpressure protection, the lid can not be opened if the pan is under pressure and so on. Moreover, they sometimes have two (or more) positions, even though it is not necessary, the small area can be used in, for example, vegetables. Also, don’t have a fresh pressure pot not escape continuous steam. There is often a useful indicator which indicates to whether the stove/burner must be adjusted higher or lower to maintain with minimal energy (cost) operating temperature (and pressure).
Advantages and disadvantages of a pressure cooker
Shorter cooking times (faster finished cooking), of course, is particularly worthwhile for dishes that normally require much time, like a stew with beef. Cooking times are final proof 1/3 of the regular cooking time. A stew usually 3 hours should simmer with the pressure cooker in an hour set! For vegetables that typically shortly cooking is a pressure cooker quickly too much hassle and gives wing to no time savings.
- Significantly lower energy consumption (up to 90%), saving on energy and the environment.
- Healthier and tastier.
- Better retention of color and flavor, vitamins and minerals.
Modern quick buy pans are often equipped with baskets and grids allowing multiple dishes at the same time can, for example, vegetables and potatoes. The disadvantage here is that the smell/taste (partly) can mingle with each other and that it is less useful as there are large differences in cooking time. An advantage of a basket is that, for example, the vegetable is not in the water, but above it, they will make the steamed and still continue to retain more of the vitamins and minerals.
Disadvantages of a pressure cooker, in particular, the purchase price, the weight (rather a thick pan and lid about the pressure), and a greater risk of burns due to the high pressure and temperature. Furthermore, the service life will be shorter than a conventional pan or maintenance is required in the form of, for example, a new sealing ring. However, many manufacturers now offer a ten-year warranty. Another disadvantage is that it is not possible to watch during the cooking as in the pan how it stands, or to further add some ingredients.