A pressure cooker on the hob is often seen with a natural sense of fear,
as if it might explode at any time. The device is, if properly maintained,
equipped with all the necessary instruments to guarantee proper and safe operation.
The pressure cooker: safe cooking
The safety of the pressure cooker depends on the presence of the pressure valve, a simple but efficacious mechanism consisting of a small hole in the cover, closed by a metal weight calibrated to shunt to one side when the pressure inside the reaches a given value allowing the excess vapour to escape, thus restoring the balance of the internal pressure. The discharge of excess steam is marked by the distinctive whistle or gurgle. When this occurs, it is wise to reduce the flame or heat under the pressure cooker.
Actually, the pressure cooker is fitted with two valves. In addition to the operating valve, as explained above, the cooker also has a safety valve that is calibrated to open at greater pressure. This consists of a rubber stopper that is forced out of its seat when internal pressure exceeds the safety threshold, creating another discharge for excess steam.
A few fundamental rules
- Do not place sealed containers and cans inside the pressure cooker because they might explode when subjected to the internal pressure.
- Place the pressure cooker on a burner, the diameter of which is not greater than the bottom of the cooker, to ensure precise control of the temperature.
- Do not place the pressure cooker on the burner before filling it with the quantity of liquid needed to cook the food, because it would burn otherwise. Pressure cooking can never be done without water. The necessary quantity of liquid is greater for foods that tend to absorb much water during cooking, but is however much less than the liquid required by recipes based on cooking in traditional pots.
- Never fill the pressure cooker beyond three quarters of its capacity (counting cooking liquid and the foods) to prevent the boiling liquid or the foam from entering into contact with the escape valve and preventing its regular functioning. When cooking foods that tend to swell (such as rice or lentils), do not fill the cooker more than half full. To facilitate this operation, many pressure cookers have a mark indicating the maximum filling level.
- Avoid cooking foods wrapped in paper or foil. Whatever the material of the wrapping, it could block the valve opening and prevent the valve from functioning.
- Absolutely never remove the hermetic cover during boiling, to avoid overspilling of the contents due to the internal pressure.
- When cooking is finished, turn off the fire and wait a few seconds before opening the pressure cooker. Actually, it is preferable to open the pressure valve to release extra vapour before opening the cooker. In alternative, the closed pressure cooker can be rinsed under running water to cool it more quickly and to condense any vapour inside, but it always necessary to follow the manufacturer’s instructions in these cases.
What you can cook in the pressure cooker
The pressure cooker is especially useful for foods that require long cooking, such as legumes and cereals, because it significantly shortens the cooking time, by up to one third of that required for normal steaming. For the same reason, and considering that once the cooker is closed, it is not possible to see how cooking is progressing, it is necessary to control the timing carefully. Cooking time must be calculated accurately to avoid errors of just a few minutes, that might lead quickly to overcooking.
The pressure cooker, by its nature, is not appropriate for cooking foods with full-bodied flavours such as roasts. With steaming, it is not possible to brown the surfaces or to stew. However, it is possible to give the foods a golden finish by giving them a browning in a traditional pot before or after pressure cooking.
It is also important to remember, with respect to a normal pot, that the pressure cooker needs more accurate periodic maintenance to verify the correct functioning of the steam release valve and the hermetic gasket of the recipient.
How Much Do You Know…?
Humid heat cooking techniques include:
Steaming is often indicated as a healthier method of cooking because it preserves the most vitamin and mineral content of foods.