A pressure cooker is a brilliant invention that has long been firmly established in our everyday life. It allows you to quickly cook any dishes, even from slowly digesting foods under ordinary conditions of heat treatment, while maintaining the majority of nutrients and taste.
Varieties of pressure cookers
Now there are many of their varieties:
- having various volumes - from 0.5 to 40 liters (the most optimal 3-5 liters);
- mechanical for cooking on the stove;
- electric with a heating device and control panel;
- characterized by body materials and design complexity.
But they all work on the same principle - in a hermetically sealed container under the influence of high pressure obtained from steam when heating water, the temperature regime increases to a level exceeding the boiling point of 100 ° C under ordinary conditions. It can reach up to 120С, as a result of which cooking is much faster.
Important! Modern pressure cookers are made of different materials (aluminum, stainless steel, Teflon coating). In aluminum, it is not recommended to cook salty or acidic dishes, since when the metal is oxidized with the release of harmful substances.
Pressure cooker pressure
The boiling point of a liquid depends on the level of atmospheric pressure. In vivo and oxygen supply, it is impossible to increase the temperature of the liquid above 100C. And in high mountain regions, where atmospheric pressure is low, water boils even at lower temperatures (per kilometer of altitude lower by 4C), which significantly prolongs the term of heat treatment of products.
In conditions without oxygen access, a pressure is created in the hermetically sealed container lid, which affects the temperature increase - every 10 mmHg gives an increase of about 0.3 ° C. Based on this law of physics, a pressure cooker was invented, which significantly accelerates the preparation of products.
Important! It is better to choose pressure cookers with hermetic gaskets at the junction of the bowl and lid, and protect them from damage. The slightest deformation will break the tightness and render the dishes unusable. This is especially true for pressure cookers without gaskets made of special rubber.
Temperature dependent
Each model has two temperature conditions:
- At a pressure of 0.3 bar, the maximum cooking temperature will be up to 109C. This mode allows you to cook products with a soft structure - vegetables, fish, poultry.
- The second mode at a pressure of 0.7 bar gives a temperature of 166C (in some models up to 120C). This allows you to quickly cook meat, beans and other slowly digested foods.
Reference! For comparison, rice cooks in a slow cooker for 40 minutes, and in a pressure cooker 12 minutes, for cooking chicken in a slow cooker it takes about an hour, and in a pressure cooker 15 minutes, jellied meat in a slow cooker takes 2-3 hours, and in a pressure cooker only 40 minutes.
What pressure does the valve hold in the pressure cooker?
Pressure cookers are equipped for safe operation with safety valves on the covers - main and emergency (some models even have 2 spare ones). Valves regulate excess pressure relief. If this is not done, then the unit may explode at the maximum level.
Mechanical models that require more careful handling - when heating on a gas or electric stove, you need to ensure that they do not overheat. Modern ones with protective valves are safer - when the pressure inside the pan increases to the maximum permissible level, the main valve is activated and steam is released. The emergency is set to a higher level of pressure and works in critical situations when the main one has failed. Electric pressure cookers have automatic temperature control.
What maximum pressure can a pressure cooker withstand?
Due to the high pressure in the pressure cooker, the following measures are taken for safety:
- excess steam valves;
- mechanical locks on the covers to protect against accidental opening;
- electronic devices for adjusting pressure;
- The lid cannot be opened immediately after switching off - you need to wait until the pressure decreases or speed up this process with cold water.
Depending on the models, the maximum allowable pressure can be different - from 1 to 4.5 bar. According to customer reviews, there are times when the tanks explode at 2.5 bar. This leads to injuries, burns, damage to surrounding objects. Therefore, use pressure cookers with extreme caution. Each of them is accompanied by an operating manual, which indicates the maximum permissible level.
Even models that are well equipped with protective devices can malfunction if they are used improperly - when the valves become clogged, if the lid is opened while the pressure cooker is still hot (hot spatter is produced that causes burns).
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