Pressure cooker

A precious ally in the kitchen

The pressure cooker proves to be a useful ally in the kitchen, a friend - above all - of low calorie diets with a touch of practicality. In fact, it allows you to cook "steamed" foods at a higher pressure than the environment, significantly reducing normal cooking times.

The pressure cooker is very similar to traditional cookware, with two main differences: the thicker walls, made of stainless steel or heavy aluminum, and the lid which guarantees an airtight seal and the possible release of excess vapors through the special valve. In the lid there is a rubber gasket that allows it to adhere perfectly to the edges of the pot, a device, usually a metallic lever, for hermetic closure, and precisely a pair of valves to let the excess steam out once the maximum pressure is reached .

Pressure cooker how does it work?

The operating principle of the pressure cooker is quite simple; thanks to the presence of a hermetically sealed lid, it keeps inside most of the water particles normally dispersed by evaporation, which are stratified by exerting a certain pressure on the cooking liquid; this pressure, in fact, can ideally be imagined as a piston that pushes the cooking liquid downwards, opposing its boiling because the water molecules have more difficulty in leaving the liquid in the form of vapor. Consequently, inside this pot the water compressed by the steam reaches boiling no more at 100 ° C but at 120-130 ° C, significantly shortening the cooking times of the foods; if you want it is the exact opposite of what happens in high ground, where - due to the lower atmospheric pressure (less layer of air particles that press on the liquid) - the water reaches boiling at a lower temperature than the level of sea. It should be noted that, regardless of the atmospheric pressure, once the boiling point is reached, the water maintains its temperature constant even providing additional heat to the system.

Pressure cooker: advantages

Particularly suitable for foods that require prolonged cooking, such as legumes and cereals, the pressure cooker can significantly speed up this phase, saving time, effort and energy, useful not only for the domestic economy but also for the environment ( fuel is saved both to bring the water to the boil and to keep it in this state). Generally, in a pressure cooker, foods cook in less than half or even a third of the time. Those who choose the pressure cooker also entrusts it with the burden of cooking, since it does not require any attention or supervision by the cook, an element that translates into a disadvantage for those who, during cooking, want to carefully check what happens in pot. The pressure cooker must however be checked in the first minutes of cooking, so as to reduce the flame to a minimum when the valve starts whistling.
The pressure cooker allows a more homogeneous distribution of the heat and allows to keep the cooking liquids inside, together with the vapors, the perfumes and the aromas released by the food. It is therefore a useful aid especially for boiled, stewed dishes and vegetables that are reluctant to cook quickly.
Through the special basket, it allows you to quickly steam cook, benefiting from all the advantages of this cooking method, especially in healthy terms in preserving vitamins and minerals, destroyed in lower percentages compared to long cooking.
Since the dispersion of natural aromas is clearly inferior, it is possible to reduce the quantity of spices, salt and various seasonings.
When the cooking is quite advanced but not yet completed you can, according to experience, turn off the heat in order to find the food ready and still warm after a few hours.
Cooking at high temperatures improves the digestibility of cereals and legumes, while - given the shorter cooking time - it does not alter the thermolabile vitamins.
Typically, pressure cookers are equipped with a series of accessories to help cook various foods, such as steam cooking baskets, grills to reduce the boiled effect of meat, preventing it from coming into contact with water, and bowl for cook pies, timbales, creams, puddings and vegetables.

Pressure cooker: disadvantages

Cost for purchasing more than traditional pans.
You can't control what's cooking because of the lid, so it's hard to make sure everything goes well; in this sense it is necessary to rely on the chronometer and experience.
As a general rule, cooking times with a pressure cooker are one third of what is required to cook the same dish with traditional pans. If on the one hand this allows to shorten significantly the cooking times - for the same principle - five minutes too much equals to a quarter of an hour in the traditional pot, with the risk of overcooking the food.
Due to the presence of steam inside it, the pressure cooker is not suitable for lovers of full-bodied flavors, such as roasts. In fact the pressure cooker does not brown or stove; eventually, those who wish to give a certain gilding to the food can pass them in a traditional pot over high heat before or after pressure cooking.
Requires periodic maintenance.

Is the pressure cooker safe?

The safety of the pressure cooker is guaranteed by the special relief valve, a very simple and at the same time very important mechanism consisting of a small hole kept plugged by a carefully calibrated metal weight to ensure that, once a certain pressure is reached inside the pan, be moved by gases. In this way, the small hole is released giving vent to the excess steam, the leakage of which is evidenced by the typical rumbling and boiling of the pot, an indication that the temperature has reached the ideal value and that the power of the fire must be reduced to a minimum. The vent valve thus prevents the pressure cooker from turning into a sort of bomb, a danger that has made it the subject of totally unfounded urban legends, made of explosions, destroyed walls, burned arms and so on.

In each pressure cooker there are two types of valves, the operating and safety valves, calibrated to open at a higher pressure. The latter consists of a rubber stopper which is pushed away when the internal pressure becomes excessive, creating a further possibility of venting for the steam.

Compliance with some simple rules is essential for cooking with a pressure cooker in full safety:

avoid inserting sealed containers and jars inside the pot, due to the risk of causing them to burst due to high internal pressure.
The diameter of the stove burners must be equal to or smaller than the bottom of the pan.
Do not place the pressure cooker on the flame if it has not previously been filled with a minimum quantity of liquid: otherwise the food would burn.
For pressure cooking you cannot, under any circumstances, cook dry but always with the addition of water to a variable extent depending on the amount of food and the type of cooking desired (boiled, roasted, stewed, etc.). The quantities of liquid needed are greater for foods that tend to absorb a lot of water during cooking, and vice versa, but still significantly lower than those prescribed in traditional pots. In any case, the pressure cooker should never be filled more than three-quarters of its capacity (including food), to prevent the boiling liquid or foam from ending up in close contact with the relief valve, preventing its regular operation. In many pans there is a security notch engraved on the inside, which indicates the maximum filling level, including food. If you cook dishes that tend to swell like rice, lentils, etc., fill the pressure cooker up to a maximum of 1/2.
Avoid cooking food in foil, then wrapped in an external casing of various kinds that could clog the valve and prevent it from working.
Carefully read the instruction booklet attached to the pot, which generally includes a cookbook with the cooking times of the various foods, calculated from the moment the pot reaches the operating temperature. The suggested cooking times are purely indicative and may vary depending on the amount of food and water added.
When cooked, turn off the heat and wait a few moments before opening the pressure cooker; if possible, open the operating valve to allow steam to escape; never remove the airtight lid during boiling, to prevent the contents of the pan overflowing pushed by internal pressure. Eventually, once cooked, it is possible to put the still closed pot under running water to cool it more quickly and condense the steam inside it. Follow the manufacturer's instructions.

Maintenance of the pressure cooker

Wash the pot according to your habits, using the care to store it without a lid to avoid compromising its tightness and avoiding the stagnation of bad smells; if these develop, simply boil some water and vinegar for a few minutes
The operating valve must be cleaned after each wash, unscrewing it and freeing it from accumulations of dirt; to ensure its efficiency, it must be possible to blow freely into the small hole. In the operation you can help yourself with a hard toothbrush and a little vinegar, or with a needle in case of important incrustations. Safety requires less attention, just check at each washing that the rubber cap can be expelled without obstacles, so that too much dirt does not remain around it. Periodically it will be extracted, washed with running water and lubricated with edible oil to favor its re-insertion. Follow the manufacturer's instructions.
The rubber seals of the cover must be protected from excessively aggressive detergents, which could damage them; the same goes for the abrasive sponges, to be avoided because they could damage the interior of the pot. To increase the life of the gasket it is recommended to grease it with cooking fat, after each use, at least once a month. Unlike the pot, the lid and its gasket should never be washed in the dishwasher. In general, it is not recommended to replace it every 400 hours of operation, given that over time it tends to lose its hermetic capacity. More generally, the gasket of the pressure cooker lid should be changed as soon as it becomes clear that it is no longer in perfect condition; in any case, if this were to be consumed or damaged, there would be no danger, because the steam would not be held by the pot and the pressure would simply not rise. Follow the manufacturer's instructions.